How to use Mapper.cs with Instasharp - c#

I'm a french student and I have to do a project for the semester.
I have to get medias from Instagram (with the api) and put them in a database. I use instasharp for now and I can do a request with the HttpClient class.
This returns a string with the content of the JSON request. But I've seen a class named Mapper.cs, which should match the result of the request with the different class of instasharp.
For example, if I search for a media, the mapper class should read the JSON string a create an appropriate instance of Media.
I do this kind of request: https://api.instagram.com/v1/media/search?lat=45.759723&lng=4.842223&distance=5000&client_id=My-Id&count=5
But I'm not sure of it, is somebody able to tell me what the Mapper class really does.
Here is the Mapper class, I do not understand all of the method, so I can't use it.
class Mapper {
public static object Map<T>(string json) where T : new() {
//var t = new T();
var j = JObject.Parse(json);
var t = typeof(T);
try {
var instance = Map(t, j);
// add the pure json back
if (instance != null) {
var prop = instance.GetType().GetProperty("Json");
if (prop != null) {
prop.SetValue(instance, json, null);
}
}
return instance;
}
catch (Exception ex) {
Debug.WriteLine(ex.Message);
return null;
}
}
private static object Map(Type t, JObject json) {
var instance = Activator.CreateInstance(t);
Array.ForEach(instance.GetType().GetProperties(), prop => {
var attribute = prop.GetCustomAttributes(typeof(Model.JsonMapping), false);
if (attribute.Length > 0) {
var propertyType = prop.PropertyType;
var mapsTo = ((Model.JsonMapping)attribute[0]).MapsTo;
var mappingType = ((Model.JsonMapping)attribute[0]).MapType;
switch (mappingType) {
case Model.JsonMapping.MappingType.Class:
if (json[mapsTo] != null) {
if (json[mapsTo].HasValues) {
var obj = Map(propertyType, (JObject)json[mapsTo]);
prop.SetValue(instance, obj, null);
}
}
break;
case Model.JsonMapping.MappingType.Collection:
var col = Map(propertyType, (JArray)json[mapsTo]);
prop.SetValue(instance, col, null);
break;
default:
if (json != null) {
if (json[mapsTo] != null) {
// special case for datetime because it comes in Unix format
if (prop.PropertyType == typeof(DateTime))
prop.SetValue(instance, UnixTimeStampToDateTime(json[mapsTo].ToString()), null);
else
prop.SetValue(instance, Convert.ChangeType(json[mapsTo].ToString(), prop.PropertyType), null);
}
}
break;
}
}
});
return instance;
}
private static IList Map(Type t, JArray json) {
var type = t.GetGenericArguments()[0];
// This will produce List<Image> or whatever the original element type is
var listType = typeof(List<>).MakeGenericType(type);
var result = (IList)Activator.CreateInstance(listType);
if (json != null) {
foreach (var j in json)
if (type.Name == "String" || type.Name == "Int32")
result.Add(j.ToString());
else result.Add(Map(type, (JObject)j));
}
return result;
}
private static DateTime UnixTimeStampToDateTime(string unixTimeStamp) {
// Unix timestamp is seconds past epoch
double unixTime = Convert.ToDouble(unixTimeStamp);
System.DateTime dtDateTime = new DateTime(1970, 1, 1, 0, 0, 0, 0);
dtDateTime = dtDateTime.AddSeconds(unixTime).ToLocalTime();
return dtDateTime;
}
private static void SetPropertyValue(PropertyInfo prop, object instance, object value) {
prop.SetValue(instance, Convert.ChangeType(value, prop.PropertyType), null);
}
}
And that is what I tried, but it doesn't work, "Erreur 540 'InstaSharp.Mapper.Map(string)' is not accessible" (something like this, I translated the error myself)
And this one "Error 539 The type or namespace name 'media' is not found ( a using directive or an assembly reference is it missing ?"
InstaSharp.Model.Media media = new InstaSharp.Model.Media();
InstaSharp.Mapper.Map<media>(reponse);
I really don't know how to use the Mapper class because I never saw a class like that (I started to use C# only 6 month ago)

The Map<T> method is expecting a type, so the type of media, not the instance media. Your usage should be something like:
InstaSharp.Mapper.Map<InstaSharp.Model.Media>(response);
As for what the class does, it exposes one static method Map<T>(string) and looks like it uses JSON.net to deserialize the string parameter into an instance of the type T with data values mapped from the JSON.
If you wanted a List<T> of Media, you'd do much the same thing as before:
InstaSharp.Mapper.Map<List<InstaSharp.Model.Media>>(response);
Lastly, because the result of Map<T> is an object, you'll need to cast it or use a dynamic variable to actually do anything.
var x = (List<Model.Media>)Mapper.Map<List<Model.Media>>(response);
To specify what class properties map to what json property, you'll need to add the Model.JsonMapping attribute to your properties and specify the MapTo attribute option.
[Model.JsonMapping(MapTo="someJsonProperty")]
public string SomeProperty {get;set;}

Related

How to use property in dynamic class if i know the name of it [duplicate]

I am trying implement the Data transformation using Reflection1 example in my code.
The GetSourceValue function has a switch comparing various types, but I want to remove these types and properties and have GetSourceValue get the value of the property using only a single string as the parameter. I want to pass a class and property in the string and resolve the value of the property.
Is this possible?
1 Web Archive version of original blog post
public static object GetPropValue(object src, string propName)
{
return src.GetType().GetProperty(propName).GetValue(src, null);
}
Of course, you will want to add validation and whatnot, but that is the gist of it.
How about something like this:
public static Object GetPropValue(this Object obj, String name) {
foreach (String part in name.Split('.')) {
if (obj == null) { return null; }
Type type = obj.GetType();
PropertyInfo info = type.GetProperty(part);
if (info == null) { return null; }
obj = info.GetValue(obj, null);
}
return obj;
}
public static T GetPropValue<T>(this Object obj, String name) {
Object retval = GetPropValue(obj, name);
if (retval == null) { return default(T); }
// throws InvalidCastException if types are incompatible
return (T) retval;
}
This will allow you to descend into properties using a single string, like this:
DateTime now = DateTime.Now;
int min = GetPropValue<int>(now, "TimeOfDay.Minutes");
int hrs = now.GetPropValue<int>("TimeOfDay.Hours");
You can either use these methods as static methods or extensions.
Add to any Class:
public class Foo
{
public object this[string propertyName]
{
get { return this.GetType().GetProperty(propertyName).GetValue(this, null); }
set { this.GetType().GetProperty(propertyName).SetValue(this, value, null); }
}
public string Bar { get; set; }
}
Then, you can use as:
Foo f = new Foo();
// Set
f["Bar"] = "asdf";
// Get
string s = (string)f["Bar"];
What about using the CallByName of the Microsoft.VisualBasic namespace (Microsoft.VisualBasic.dll)? It uses reflection to get properties, fields, and methods of normal objects, COM objects, and even dynamic objects.
using Microsoft.VisualBasic;
using Microsoft.VisualBasic.CompilerServices;
and then
Versioned.CallByName(this, "method/function/prop name", CallType.Get).ToString();
Great answer by jheddings. I would like to improve it by allowing referencing of aggregated arrays or collections of objects, so that propertyName could be property1.property2[X].property3:
public static object GetPropertyValue(object srcobj, string propertyName)
{
if (srcobj == null)
return null;
object obj = srcobj;
// Split property name to parts (propertyName could be hierarchical, like obj.subobj.subobj.property
string[] propertyNameParts = propertyName.Split('.');
foreach (string propertyNamePart in propertyNameParts)
{
if (obj == null) return null;
// propertyNamePart could contain reference to specific
// element (by index) inside a collection
if (!propertyNamePart.Contains("["))
{
PropertyInfo pi = obj.GetType().GetProperty(propertyNamePart);
if (pi == null) return null;
obj = pi.GetValue(obj, null);
}
else
{ // propertyNamePart is areference to specific element
// (by index) inside a collection
// like AggregatedCollection[123]
// get collection name and element index
int indexStart = propertyNamePart.IndexOf("[")+1;
string collectionPropertyName = propertyNamePart.Substring(0, indexStart-1);
int collectionElementIndex = Int32.Parse(propertyNamePart.Substring(indexStart, propertyNamePart.Length-indexStart-1));
// get collection object
PropertyInfo pi = obj.GetType().GetProperty(collectionPropertyName);
if (pi == null) return null;
object unknownCollection = pi.GetValue(obj, null);
// try to process the collection as array
if (unknownCollection.GetType().IsArray)
{
object[] collectionAsArray = unknownCollection as object[];
obj = collectionAsArray[collectionElementIndex];
}
else
{
// try to process the collection as IList
System.Collections.IList collectionAsList = unknownCollection as System.Collections.IList;
if (collectionAsList != null)
{
obj = collectionAsList[collectionElementIndex];
}
else
{
// ??? Unsupported collection type
}
}
}
}
return obj;
}
If I use the code from Ed S. I get
'ReflectionExtensions.GetProperty(Type, string)' is inaccessible due to its protection level
It seems that GetProperty() is not available in Xamarin.Forms. TargetFrameworkProfile is Profile7 in my Portable Class Library (.NET Framework 4.5, Windows 8, ASP.NET Core 1.0, Xamarin.Android, Xamarin.iOS, Xamarin.iOS Classic).
Now I found a working solution:
using System.Linq;
using System.Reflection;
public static object GetPropValue(object source, string propertyName)
{
var property = source.GetType().GetRuntimeProperties().FirstOrDefault(p => string.Equals(p.Name, propertyName, StringComparison.OrdinalIgnoreCase));
return property?.GetValue(source);
}
Source
About the nested properties discussion, you can avoid all the reflection stuff if you use the DataBinder.Eval Method (Object, String) as below:
var value = DataBinder.Eval(DateTime.Now, "TimeOfDay.Hours");
Of course, you'll need to add a reference to the System.Web assembly, but this probably isn't a big deal.
The method to call has changed in .NET Standard (as of 1.6). Also we can use C# 6's null conditional operator.
using System.Reflection;
public static object GetPropValue(object src, string propName)
{
return src.GetType().GetRuntimeProperty(propName)?.GetValue(src);
}
The below method works perfect for me:
class MyClass {
public string prop1 { set; get; }
public object this[string propertyName]
{
get { return this.GetType().GetProperty(propertyName).GetValue(this, null); }
set { this.GetType().GetProperty(propertyName).SetValue(this, value, null); }
}
}
To get the property value:
MyClass t1 = new MyClass();
...
string value = t1["prop1"].ToString();
To set the property value:
t1["prop1"] = value;
public static List<KeyValuePair<string, string>> GetProperties(object item) //where T : class
{
var result = new List<KeyValuePair<string, string>>();
if (item != null)
{
var type = item.GetType();
var properties = type.GetProperties(BindingFlags.Public | BindingFlags.Instance);
foreach (var pi in properties)
{
var selfValue = type.GetProperty(pi.Name).GetValue(item, null);
if (selfValue != null)
{
result.Add(new KeyValuePair<string, string>(pi.Name, selfValue.ToString()));
}
else
{
result.Add(new KeyValuePair<string, string>(pi.Name, null));
}
}
}
return result;
}
This is a way to get all properties with their values in a List.
Using PropertyInfo of the System.Reflection namespace. Reflection compiles just fine no matter what property we try to access. The error will come up during run-time.
public static object GetObjProperty(object obj, string property)
{
Type t = obj.GetType();
PropertyInfo p = t.GetProperty("Location");
Point location = (Point)p.GetValue(obj, null);
return location;
}
It works fine to get the Location property of an object
Label1.Text = GetObjProperty(button1, "Location").ToString();
We'll get the Location : {X=71,Y=27}
We can also return location.X or location.Y on the same way.
public class YourClass
{
//Add below line in your class
public object this[string propertyName] => GetType().GetProperty(propertyName)?.GetValue(this, null);
public string SampleProperty { get; set; }
}
//And you can get value of any property like this.
var value = YourClass["SampleProperty"];
The following code is a Recursive method for displaying the entire hierarchy of all of the Property Names and Values contained in an object's instance. This method uses a simplified version of AlexD's GetPropertyValue() answer above in this thread. Thanks to this discussion thread, I was able to figure out how to do this!
For example, I use this method to show an explosion or dump of all of the properties in a WebService response by calling the method as follows:
PropertyValues_byRecursion("Response", response, false);
public static object GetPropertyValue(object srcObj, string propertyName)
{
if (srcObj == null)
{
return null;
}
PropertyInfo pi = srcObj.GetType().GetProperty(propertyName.Replace("[]", ""));
if (pi == null)
{
return null;
}
return pi.GetValue(srcObj);
}
public static void PropertyValues_byRecursion(string parentPath, object parentObj, bool showNullValues)
{
/// Processes all of the objects contained in the parent object.
/// If an object has a Property Value, then the value is written to the Console
/// Else if the object is a container, then this method is called recursively
/// using the current path and current object as parameters
// Note: If you do not want to see null values, set showNullValues = false
foreach (PropertyInfo pi in parentObj.GetType().GetTypeInfo().GetProperties())
{
// Build the current object property's namespace path.
// Recursion extends this to be the property's full namespace path.
string currentPath = parentPath + "." + pi.Name;
// Get the selected property's value as an object
object myPropertyValue = GetPropertyValue(parentObj, pi.Name);
if (myPropertyValue == null)
{
// Instance of Property does not exist
if (showNullValues)
{
Console.WriteLine(currentPath + " = null");
// Note: If you are replacing these Console.Write... methods callback methods,
// consider passing DBNull.Value instead of null in any method object parameters.
}
}
else if (myPropertyValue.GetType().IsArray)
{
// myPropertyValue is an object instance of an Array of business objects.
// Initialize an array index variable so we can show NamespacePath[idx] in the results.
int idx = 0;
foreach (object business in (Array)myPropertyValue)
{
if (business == null)
{
// Instance of Property does not exist
// Not sure if this is possible in this context.
if (showNullValues)
{
Console.WriteLine(currentPath + "[" + idx.ToString() + "]" + " = null");
}
}
else if (business.GetType().IsArray)
{
// myPropertyValue[idx] is another Array!
// Let recursion process it.
PropertyValues_byRecursion(currentPath + "[" + idx.ToString() + "]", business, showNullValues);
}
else if (business.GetType().IsSealed)
{
// Display the Full Property Path and its Value
Console.WriteLine(currentPath + "[" + idx.ToString() + "] = " + business.ToString());
}
else
{
// Unsealed Type Properties can contain child objects.
// Recurse into my property value object to process its properties and child objects.
PropertyValues_byRecursion(currentPath + "[" + idx.ToString() + "]", business, showNullValues);
}
idx++;
}
}
else if (myPropertyValue.GetType().IsSealed)
{
// myPropertyValue is a simple value
Console.WriteLine(currentPath + " = " + myPropertyValue.ToString());
}
else
{
// Unsealed Type Properties can contain child objects.
// Recurse into my property value object to process its properties and child objects.
PropertyValues_byRecursion(currentPath, myPropertyValue, showNullValues);
}
}
}
public static TValue GetFieldValue<TValue>(this object instance, string name)
{
var type = instance.GetType();
var field = type.GetFields(BindingFlags.NonPublic | BindingFlags.Static | BindingFlags.Instance).FirstOrDefault(e => typeof(TValue).IsAssignableFrom(e.FieldType) && e.Name == name);
return (TValue)field?.GetValue(instance);
}
public static TValue GetPropertyValue<TValue>(this object instance, string name)
{
var type = instance.GetType();
var field = type.GetProperties(BindingFlags.NonPublic | BindingFlags.Static | BindingFlags.Instance).FirstOrDefault(e => typeof(TValue).IsAssignableFrom(e.PropertyType) && e.Name == name);
return (TValue)field?.GetValue(instance);
}
Dim NewHandle As YourType = CType(Microsoft.VisualBasic.CallByName(ObjectThatContainsYourVariable, "YourVariableName", CallType), YourType)
Here is another way to find a nested property that doesn't require the string to tell you the nesting path. Credit to Ed S. for the single property method.
public static T FindNestedPropertyValue<T, N>(N model, string propName) {
T retVal = default(T);
bool found = false;
PropertyInfo[] properties = typeof(N).GetProperties();
foreach (PropertyInfo property in properties) {
var currentProperty = property.GetValue(model, null);
if (!found) {
try {
retVal = GetPropValue<T>(currentProperty, propName);
found = true;
} catch { }
}
}
if (!found) {
throw new Exception("Unable to find property: " + propName);
}
return retVal;
}
public static T GetPropValue<T>(object srcObject, string propName) {
return (T)srcObject.GetType().GetProperty(propName).GetValue(srcObject, null);
}
You never mention what object you are inspecting, and since you are rejecting ones that reference a given object, I will assume you mean a static one.
using System.Reflection;
public object GetPropValue(string prop)
{
int splitPoint = prop.LastIndexOf('.');
Type type = Assembly.GetEntryAssembly().GetType(prop.Substring(0, splitPoint));
object obj = null;
return type.GetProperty(prop.Substring(splitPoint + 1)).GetValue(obj, null);
}
Note that I marked the object that is being inspected with the local variable obj. null means static, otherwise set it to what you want. Also note that the GetEntryAssembly() is one of a few available methods to get the "running" assembly, you may want to play around with it if you are having a hard time loading the type.
Have a look at the Heleonix.Reflection library. You can get/set/invoke members by paths, or create a getter/setter (lambda compiled into a delegate) which is faster than reflection. For example:
var success = Reflector.Get(DateTime.Now, null, "Date.Year", out int value);
Or create a getter once and cache for reuse (this is more performant but might throw NullReferenceException if an intermediate member is null):
var getter = Reflector.CreateGetter<DateTime, int>("Date.Year", typeof(DateTime));
getter(DateTime.Now);
Or if you want to create a List<Action<object, object>> of different getters, just specify base types for compiled delegates (type conversions will be added into compiled lambdas):
var getter = Reflector.CreateGetter<object, object>("Date.Year", typeof(DateTime));
getter(DateTime.Now);
Although the original question was about how to get the value of the property using only a single string as the parameter, it makes a lot of sense here to use an Expression rather than simply a string to ensure that the caller never uses a hard coded property name. Here is a one line version with usage:
public static class Utils
...
public static TVal GetPropertyValue<T, TVal>(T t, Expression<Func<T, TVal>> x)
=> (TVal)((x.Body as MemberExpression)?.Member as PropertyInfo)!.GetValue(t);
...
var val = Utils.GetPropertyValue(foo, p => p.Bar);
Here is a slightly better version in terms of readability a error handling:
public static TVal GetPropertyValue<T, TVal>(T t, Expression<Func<T, TVal>> x)
{
var m = (x.Body as MemberExpression)?.Member;
var p = m as PropertyInfo;
if (null == p)
throw new ArgumentException($"Unknown property: {typeof(T).Name}.{(m?.Name??"???")}");
return (TVal)p.GetValue(t);
}
In short you pass in a lambda expression reading a property. The body of the lambda - the part on the right of the fat arrow - is a member expression from which you can get the member name and which you can cast to a PropertyInfo, provided the member is actually a Property and not, for instance, a method.
In the short version, the null forgiving operator - the ! in the expression - tells the compiler that the PropertyInfo will not be null. This is a big lie and you will get a NullReferenceException at runtime. The longer version gives you the name of the property if it manages to get it.
PS: Thanks to Oleg G. for the initial version of this code :)
shorter way ....
var a = new Test { Id = 1 , Name = "A" , date = DateTime.Now};
var b = new Test { Id = 1 , Name = "AXXX", date = DateTime.Now };
var compare = string.Join("",a.GetType().GetProperties().Select(x => x.GetValue(a)).ToArray())==
string.Join("",b.GetType().GetProperties().Select(x => x.GetValue(b)).ToArray());
jheddings and AlexD both wrote excellent answers on how to resolve property strings. I'd like to throw mine in the mix, since I wrote a dedicated library exactly for that purpose.
Pather.CSharp's main class is Resolver. Per default it can resolve properties, array and dictionary entries.
So, for example, if you have an object like this
var o = new { Property1 = new { Property2 = "value" } };
and want to get Property2, you can do it like this:
IResolver resolver = new Resolver();
var path = "Property1.Property2";
object result = r.Resolve(o, path);
//=> "value"
This is the most basic example of the paths it can resolve. If you want to see what else it can, or how you can extend it, just head to its Github page.
Here's what I got based on other answers. A little overkill on getting so specific with the error handling.
public static T GetPropertyValue<T>(object sourceInstance, string targetPropertyName, bool throwExceptionIfNotExists = false)
{
string errorMsg = null;
try
{
if (sourceInstance == null || string.IsNullOrWhiteSpace(targetPropertyName))
{
errorMsg = $"Source object is null or property name is null or whitespace. '{targetPropertyName}'";
Log.Warn(errorMsg);
if (throwExceptionIfNotExists)
throw new ArgumentException(errorMsg);
else
return default(T);
}
Type returnType = typeof(T);
Type sourceType = sourceInstance.GetType();
PropertyInfo propertyInfo = sourceType.GetProperty(targetPropertyName, returnType);
if (propertyInfo == null)
{
errorMsg = $"Property name '{targetPropertyName}' of type '{returnType}' not found for source object of type '{sourceType}'";
Log.Warn(errorMsg);
if (throwExceptionIfNotExists)
throw new ArgumentException(errorMsg);
else
return default(T);
}
return (T)propertyInfo.GetValue(sourceInstance, null);
}
catch(Exception ex)
{
errorMsg = $"Problem getting property name '{targetPropertyName}' from source instance.";
Log.Error(errorMsg, ex);
if (throwExceptionIfNotExists)
throw;
}
return default(T);
}
Here is my solution. It works also with COM objects and allows to access collection/array items from COM objects.
public static object GetPropValue(this object obj, string name)
{
foreach (string part in name.Split('.'))
{
if (obj == null) { return null; }
Type type = obj.GetType();
if (type.Name == "__ComObject")
{
if (part.Contains('['))
{
string partWithoundIndex = part;
int index = ParseIndexFromPropertyName(ref partWithoundIndex);
obj = Versioned.CallByName(obj, partWithoundIndex, CallType.Get, index);
}
else
{
obj = Versioned.CallByName(obj, part, CallType.Get);
}
}
else
{
PropertyInfo info = type.GetProperty(part);
if (info == null) { return null; }
obj = info.GetValue(obj, null);
}
}
return obj;
}
private static int ParseIndexFromPropertyName(ref string name)
{
int index = -1;
int s = name.IndexOf('[') + 1;
int e = name.IndexOf(']');
if (e < s)
{
throw new ArgumentException();
}
string tmp = name.Substring(s, e - s);
index = Convert.ToInt32(tmp);
name = name.Substring(0, s - 1);
return index;
}
Whenever you want to loop over all properties in on an object and then use each value of the property must use this piece of code:
foreach (var property in request.GetType().GetProperties())
{
var valueOfProperty = property.GetValue(properties, null);
}

How do you read a simple value out of some json using System.Text.Json?

I have this json
{"id":"48e86841-f62c-42c9-ae20-b54ba8c35d6d"}
How do I get the 48e86841-f62c-42c9-ae20-b54ba8c35d6d out of it? All examples I can find show to do something like
var o = System.Text.Json.JsonSerializer.Deserialize<some-type>(json);
o.id // <- here's the ID!
But I don't have a type that fits this definition and I don't want to create one. I've tried deserializing to dynamic but I was unable to get that working.
var result = System.Text.Json.JsonSerializer.Deserialize<dynamic>(json);
result.id // <-- An exception of type 'Microsoft.CSharp.RuntimeBinder.RuntimeBinderException' occurred in System.Linq.Expressions.dll but was not handled in user code: ''System.Text.Json.JsonElement' does not contain a definition for 'id''
Can anyone give any suggestions?
edit:
I just figured out I can do this:
Guid id = System.Text.Json.JsonDocument.Parse(json).RootElement.GetProperty("id").GetGuid();
This does work - but is there a better way?
you can deserialize to a Dictionary:
var dict = System.Text.Json.JsonSerializer.Deserialize<Dictionary<string, string>>(json)
Or just deserialize to Object which will yield a JsonElement that you can call GetProperty on.
Support for JsonObject has been added in .NET 6 using System.Text.Json.Nodes.
Example:
const string Json = "{\"MyNumber\":42, \"MyArray\":[10,11]}";
// dynamic
{
dynamic obj = JsonNode.Parse(Json);
int number = (int)obj["MyNumber"];
Debug.Assert(number == 42);
obj["MyString"] = "Hello";
Debug.Assert((string)obj["MyString"] == "Hello");
}
// JsonObject
{
JsonObject obj = JsonNode.Parse(Json).AsObject();
int number = (int)obj["MyNumber"];
Debug.Assert(number == 42);
obj["MyString"] = "Hello";
Debug.Assert((string)obj["MyString"] == "Hello");
}
Sources:
https://github.com/dotnet/runtime/issues/53195
https://github.com/dotnet/runtime/issues/45188
I've recently migrated a project from ASP.NET Core 2.2 to 3, and I'm having this inconvenience. In our team we value lean dependencies, so we are trying to avoid including Newtonsoft.JSON back and try using System.Text.Json. We also decided not to use a ton of POCO objects just for JSON serialization, because our backend models are more complex than needed for Web APIs. Also, because of nontrivial behaviour encapsulation, the backend models cannot be easily used to serialize/deserialize JSON strings.
I understand that System.Text.Json is supposed to be faster than Newtonsoft.JSON, but I believe this has a lot to do with ser/deser from/to specific POCO classes. Anyway, speed was not on our list of pros/cons for this decision, so YMMV.
Long story short, for the time being I wrote a small dynamic object wrapper that unpacks the JsonElements from System.Text.Json and tries to convert/cast as best as possible. The typical usage is to read the request body as a dynamic object. Again, I'm pretty sure this approach kills any speed gains, but that was not a concern for our use case.
This is the class:
public class ReflectionDynamicObject : DynamicObject {
public JsonElement RealObject { get; set; }
public override bool TryGetMember (GetMemberBinder binder, out object result) {
// Get the property value
var srcData = RealObject.GetProperty (binder.Name);
result = null;
switch (srcData.ValueKind) {
case JsonValueKind.Null:
result = null;
break;
case JsonValueKind.Number:
result = srcData.GetDouble ();
break;
case JsonValueKind.False:
result = false;
break;
case JsonValueKind.True:
result = true;
break;
case JsonValueKind.Undefined:
result = null;
break;
case JsonValueKind.String:
result = srcData.GetString ();
break;
case JsonValueKind.Object:
result = new ReflectionDynamicObject {
RealObject = srcData
};
break;
case JsonValueKind.Array:
result = srcData.EnumerateArray ()
.Select (o => new ReflectionDynamicObject { RealObject = o })
.ToArray ();
break;
}
// Always return true; other exceptions may have already been thrown if needed
return true;
}
}
and this is an example usage, to parse the request body - one part is in a base class for all my WebAPI controllers, that exposes the body as a dynamic object:
[ApiController]
public class WebControllerBase : Controller {
// Other stuff - omitted
protected async Task<dynamic> JsonBody () {
var result = await JsonDocument.ParseAsync (Request.Body);
return new ReflectionDynamicObject {
RealObject = result.RootElement
};
}
}
and can be used in the actual controller like this:
//[...]
[HttpPost ("")]
public async Task<ActionResult> Post () {
var body = await JsonBody ();
var name = (string) body.Name;
//[...]
}
//[...]
If needed, you can integrate parsing for GUIDs or other specific data types as needed - while we all wait for some official / framework-sanctioned solution.
Actual way to parse string in System.Text.Json (.NET Core 3+)
var jsonStr = "{\"id\":\"48e86841-f62c-42c9-ae20-b54ba8c35d6d\"}";
using var doc = JsonDocument.Parse(jsonStr);
var root = doc.RootElement;
var id = root.GetProperty("id").GetGuid();
You can use the following extension method to query data like "xpath"
public static string? JsonQueryXPath(this string value, string xpath, JsonSerializerOptions? options = null) => value.Deserialize<JsonElement>(options).GetJsonElement(xpath).GetJsonElementValue();
public static JsonElement GetJsonElement(this JsonElement jsonElement, string xpath)
{
if (jsonElement.ValueKind is JsonValueKind.Null or JsonValueKind.Undefined)
return default;
string[] segments = xpath.Split(new[] {'.'}, StringSplitOptions.RemoveEmptyEntries);
foreach (var segment in segments)
{
if (int.TryParse(segment, out var index) && jsonElement.ValueKind == JsonValueKind.Array)
{
jsonElement = jsonElement.EnumerateArray().ElementAtOrDefault(index);
if (jsonElement.ValueKind is JsonValueKind.Null or JsonValueKind.Undefined)
return default;
continue;
}
jsonElement = jsonElement.TryGetProperty(segment, out var value) ? value : default;
if (jsonElement.ValueKind is JsonValueKind.Null or JsonValueKind.Undefined)
return default;
}
return jsonElement;
}
public static string? GetJsonElementValue(this JsonElement jsonElement) => jsonElement.ValueKind != JsonValueKind.Null &&
jsonElement.ValueKind != JsonValueKind.Undefined
? jsonElement.ToString()
: default;
Simple to use as follows
string raw = #"{
""data"": {
""products"": {
""edges"": [
{
""node"": {
""id"": ""gid://shopify/Product/4534543543316"",
""featuredImage"": {
""originalSrc"": ""https://cdn.shopify.com/s/files/1/0286/pic.jpg"",
""id"": ""gid://shopify/ProductImage/146345345339732""
}
}
},
{
""node"": {
""id"": ""gid://shopify/Product/123456789"",
""featuredImage"": {
""originalSrc"": ""https://cdn.shopify.com/s/files/1/0286/pic.jpg"",
""id"": [
""gid://shopify/ProductImage/123456789"",
""gid://shopify/ProductImage/666666666""
]
},
""1"": {
""name"": ""Tuanh""
}
}
}
]
}
}
}";
System.Console.WriteLine(raw2.QueryJsonXPath("data.products.edges.0.node.featuredImage.id"));
I wrote an extension method for this purpose. You can safely use as following:
var jsonElement = JsonSerializer.Deserialize<JsonElement>(json);
var guid = jsonElement.TryGetValue<Guid>("id");
This is the extension class.
public static class JsonElementExtensions
{
private static readonly JsonSerializerOptions options = new() { PropertyNameCaseInsensitive = true };
public static T? TryGetValue<T>(this JsonElement element, string propertyName)
{
if (element.ValueKind != JsonValueKind.Object)
{
return default;
}
element.TryGetProperty(propertyName, out JsonElement property);
if (property.ValueKind == JsonValueKind.Undefined ||
property.ValueKind == JsonValueKind.Null)
{
return default;
}
try
{
return property.Deserialize<T>(options);
}
catch (JsonException)
{
return default;
}
}
}
Reason
The reason behind using this extension instead of JsonNode class is because if you need a Controller method accepts just an object without exposing it's model class Asp.Net Core model binding uses JsonElement struct to map the json string. At this point (as far as I know) there is no simple way to convert the JsonElement to JsonNode and when your object can be anything the JsonElement methods will throw exceptions for undefined fields while JsonNode don't.
[HttpPost]
public IActionResult Post(object setupObject)
{
var setup = (JsonElement)setupObject;
var id = setup.TryGetValue<Guid>("id");
var user = setup.TryGetValue<User?>("user");
var account = setup.TryGetValue<Account?>("account");
var payments = setup.TryGetValue<IEnumerable<Payments>?>("payments");
// ...
return Ok();
}
update to .NET Core 3.1 to support
public static dynamic FromJson(this string json, JsonSerializerOptions options = null)
{
if (string.IsNullOrEmpty(json))
return null;
try
{
return JsonSerializer.Deserialize<ExpandoObject>(json, options);
}
catch
{
return null;
}
}
You can also deserialize your json to an object of your target class, and then read its properties as per normal:
var obj = DeSerializeFromStrToObj<ClassToSerialize>(jsonStr);
Console.WriteLine($"Property: {obj.Property}");
where DeSerializeFromStrToObj is a custom class that makes use of reflection to instantiate an object of a targeted class:
public static T DeSerializeFromStrToObj<T>(string json)
{
try
{
var o = (T)Activator.CreateInstance(typeof(T));
try
{
var jsonDict = JsonSerializer.Deserialize<Dictionary<string, string>>(json);
var props = o.GetType().GetProperties();
if (props == null || props.Length == 0)
{
Debug.WriteLine($"Error: properties from target class '{typeof(T)}' could not be read using reflection");
return default;
}
if (jsonDict.Count != props.Length)
{
Debug.WriteLine($"Error: number of json lines ({jsonDict.Count}) should be the same as number of properties ({props.Length})of our class '{typeof(T)}'");
return default;
}
foreach (var prop in props)
{
if (prop == null)
{
Debug.WriteLine($"Error: there was a prop='null' in our target class '{typeof(T)}'");
return default;
}
if (!jsonDict.ContainsKey(prop.Name))
{
Debug.WriteLine($"Error: jsonStr does not refer to target class '{typeof(T)}'");
return default;
}
var value = jsonDict[prop.Name];
Type t = Nullable.GetUnderlyingType(prop.PropertyType) ?? prop.PropertyType;
object safeValue = value ?? Convert.ChangeType(value, t);
prop.SetValue(o, safeValue, null); // initialize property
}
return o;
}
catch (Exception e2)
{
Debug.WriteLine(e2.Message);
return o;
}
}
catch (Exception e)
{
Debug.WriteLine(e.Message);
return default;
}
}
You can test your jsons for example here
Here you find a complete working example with different ways of serialization and deserialization that might be of interest for you and/or future readers:
using System;
using System.Collections.Generic;
using System.Text.Json;
using static Json_Tests.JsonHelpers;
namespace Json_Tests
{
public class Class1
{
public void Test()
{
var obj1 = new ClassToSerialize();
var jsonStr = obj1.ToString();
// if you have the class structure for the jsonStr (for example, if you have created the jsonStr yourself from your code):
var obj2 = DeSerializeFromStrToObj<ClassToSerialize>(jsonStr);
Console.WriteLine($"{nameof(obj2.Name)}: {obj2.Name}");
// if you do not have the class structure for the jsonStr (forexample, jsonStr comes from a 3rd party service like the web):
var obj3 = JsonSerializer.Deserialize<object>(jsonStr) as JsonElement?;
var propName = nameof(obj1.Name);
var propVal1 = obj3?.GetProperty("Name");// error prone
Console.WriteLine($"{propName}: {propVal1}");
JsonElement propVal2 = default;
obj3?.TryGetProperty("Name", out propVal2);// error prone
Console.WriteLine($"{propName}: {propVal2}");
var obj4 = DeSerializeFromStrToDict(jsonStr);
foreach (var pair in obj4)
Console.WriteLine($"{pair.Key}: {pair.Value}");
}
}
[Serializable]
public class ClassToSerialize
{
// important: properties must have at least getters
public string Name { get; } = "Paul";
public string Surname{ get; set; } = "Efford";
public override string ToString() => JsonSerializer.Serialize(this, new JsonSerializerOptions { WriteIndented = true });
}
public static class JsonHelpers
{
/// <summary>
/// to use if you do not have the class structure for the jsonStr (forexample, jsonStr comes from a 3rd party service like the web)
/// </summary>
public static Dictionary<string, string> DeSerializeFromStrToDict(string json)
{
try
{
return JsonSerializer.Deserialize<Dictionary<string, string>>(json);
}
catch (Exception e)
{
Console.WriteLine(e.Message);
return new Dictionary<string, string>(); // return empty
}
}
/// <summary>
/// to use if you have the class structure for the jsonStr (for example, if you have created the jsonStr yourself from your code)
/// </summary>
public static T DeSerializeFromStrToObj<T>(string json) // see this: https://json2csharp.com/#
{
try
{
var o = (T)Activator.CreateInstance(typeof(T));
try
{
var jsonDict = JsonSerializer.Deserialize<Dictionary<string, string>>(json);
var props = o.GetType().GetProperties();
if (props == null || props.Length == 0)
{
Console.WriteLine($"Error: properties from target class '{typeof(T)}' could not be read using reflection");
return default;
}
if (jsonDict.Count != props.Length)
{
Console.WriteLine($"Error: number of json lines ({jsonDict.Count}) should be the same as number of properties ({props.Length})of our class '{typeof(T)}'");
return default;
}
foreach (var prop in props)
{
if (prop == null)
{
Console.WriteLine($"Error: there was a prop='null' in our target class '{typeof(T)}'");
return default;
}
if (!jsonDict.ContainsKey(prop.Name))
{
Console.WriteLine($"Error: jsonStr does not refer to target class '{typeof(T)}'");
return default;
}
var value = jsonDict[prop.Name];
Type t = Nullable.GetUnderlyingType(prop.PropertyType) ?? prop.PropertyType;
object safeValue = value ?? Convert.ChangeType(value, t);
prop.SetValue(o, safeValue, null); // initialize property
}
return o;
}
catch (Exception e2)
{
Console.WriteLine(e2.Message);
return o;
}
}
catch (Exception e)
{
Console.WriteLine(e.Message);
return default;
}
}
}
}

Enum won't serialize from non string value

I have this property ScheduleDatePeriod as a enum on this EditEventScheduleSettingsModel class. I serialize as JSON to the page within javascript which makes the property Period: 1. When I submit this to the server as Period: 1, the enum is always null. Why is this?
Property
public ScheduleDatePeriod? Period { get; set; }
Action
[HttpPost]
public virtual ActionResult Grid(int eventId, EditEventScheduleSettingsModel settings)
{
JSON
{
Period: 1
}
Enum
[DataContract(Namespace = "")]
public enum ScheduleDatePeriod
{
[EnumMember(Value = "0"), Display(Name = "None")]
None = 0,
[EnumMember(Value = "1"), Display(Name = "Day")]
Day = 1,
[EnumMember(Value = "2"), Display(Name = "Week")]
Week = 2
}
ValueProviderFactory
public class JsonNetValueProviderFactory : ValueProviderFactory
{
public override IValueProvider GetValueProvider(ControllerContext controllerContext)
{
// first make sure we have a valid context
if (controllerContext == null)
throw new ArgumentNullException("controllerContext");
// now make sure we are dealing with a json request
if (!controllerContext.HttpContext.Request.ContentType.StartsWith("application/json", StringComparison.OrdinalIgnoreCase))
return null;
// get a generic stream reader (get reader for the http stream)
var streamReader = new StreamReader(controllerContext.HttpContext.Request.InputStream);
// convert stream reader to a JSON Text Reader
var jsonReader = new JsonTextReader(streamReader);
// tell JSON to read
if (!jsonReader.Read())
return null;
// make a new Json serializer
var jsonSerializer = new JsonSerializer();
jsonSerializer.ReferenceLoopHandling = ReferenceLoopHandling.Ignore;
// add the dyamic object converter to our serializer
jsonSerializer.Converters.Add(new ExpandoObjectConverter());
// use JSON.NET to deserialize object to a dynamic (expando) object
Object jsonObject;
// if we start with a "[", treat this as an array
if (jsonReader.TokenType == JsonToken.StartArray)
jsonObject = jsonSerializer.Deserialize<List<ExpandoObject>>(jsonReader);
else
jsonObject = jsonSerializer.Deserialize<ExpandoObject>(jsonReader);
// create a backing store to hold all properties for this deserialization
var backingStore = new Dictionary<string, object>(StringComparer.OrdinalIgnoreCase);
// add all properties to this backing store
AddToBackingStore(backingStore, String.Empty, jsonObject);
// return the object in a dictionary value provider so the MVC understands it
return new DictionaryValueProvider<object>(backingStore, CultureInfo.CurrentCulture);
}
private static void AddToBackingStore(Dictionary<string, object> backingStore, string prefix, object value)
{
var d = value as IDictionary<string, object>;
if (d != null)
{
foreach (KeyValuePair<string, object> entry in d)
{
AddToBackingStore(backingStore, MakePropertyKey(prefix, entry.Key), entry.Value);
}
return;
}
var l = value as IList;
if (l != null)
{
for (int i = 0; i < l.Count; i++)
{
AddToBackingStore(backingStore, MakeArrayKey(prefix, i), l[i]);
}
return;
}
// primitive
backingStore[prefix] = value;
}
private static string MakeArrayKey(string prefix, int index)
{
return prefix + "[" + index.ToString(CultureInfo.InvariantCulture) + "]";
}
private static string MakePropertyKey(string prefix, string propertyName)
{
return (String.IsNullOrEmpty(prefix)) ? propertyName : prefix + "." + propertyName;
}
}
Global.asax
ValueProviderFactories.Factories.Remove(ValueProviderFactories.Factories.OfType<JsonValueProviderFactory>().FirstOrDefault());
ValueProviderFactories.Factories.Add(new JsonNetValueProviderFactory());
I did some testing of the JsonNetValueProviderFactory and I think I have found the cause of the problem.
The following line will parse the "Period" value as a long and not an int. The value of the enum is an int, causing the conversion to the enum to fail.
jsonObject = jsonSerializer.Deserialize<ExpandoObject>(jsonReader);
I can't really find a good solution for this, but these are workarounds
Pass in period as a string value instead
Use the default JsonValueProviderFactory
I am not sure if you provided full JSON that you used, but I tested your example with next JSON and enum was successfully deserialized (tested in fiddler).
{
"eventId": 10,
"settings":
{
"Period" : 2
}
}
Please note that you should use "settings" in JSON to match name of parameter in your method.

Deserialize JSON into C# dynamic object?

Is there a way to deserialize JSON content into a C# dynamic type? It would be nice to skip creating a bunch of classes in order to use the DataContractJsonSerializer.
If you are happy to have a dependency upon the System.Web.Helpers assembly, then you can use the Json class:
dynamic data = Json.Decode(json);
It is included with the MVC framework as an additional download to the .NET 4 framework. Be sure to give Vlad an upvote if that's helpful! However if you cannot assume the client environment includes this DLL, then read on.
An alternative deserialisation approach is suggested here. I modified the code slightly to fix a bug and suit my coding style. All you need is this code and a reference to System.Web.Extensions from your project:
using System;
using System.Collections;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Dynamic;
using System.Linq;
using System.Text;
using System.Web.Script.Serialization;
public sealed class DynamicJsonConverter : JavaScriptConverter
{
public override object Deserialize(IDictionary<string, object> dictionary, Type type, JavaScriptSerializer serializer)
{
if (dictionary == null)
throw new ArgumentNullException("dictionary");
return type == typeof(object) ? new DynamicJsonObject(dictionary) : null;
}
public override IDictionary<string, object> Serialize(object obj, JavaScriptSerializer serializer)
{
throw new NotImplementedException();
}
public override IEnumerable<Type> SupportedTypes
{
get { return new ReadOnlyCollection<Type>(new List<Type>(new[] { typeof(object) })); }
}
#region Nested type: DynamicJsonObject
private sealed class DynamicJsonObject : DynamicObject
{
private readonly IDictionary<string, object> _dictionary;
public DynamicJsonObject(IDictionary<string, object> dictionary)
{
if (dictionary == null)
throw new ArgumentNullException("dictionary");
_dictionary = dictionary;
}
public override string ToString()
{
var sb = new StringBuilder("{");
ToString(sb);
return sb.ToString();
}
private void ToString(StringBuilder sb)
{
var firstInDictionary = true;
foreach (var pair in _dictionary)
{
if (!firstInDictionary)
sb.Append(",");
firstInDictionary = false;
var value = pair.Value;
var name = pair.Key;
if (value is string)
{
sb.AppendFormat("{0}:\"{1}\"", name, value);
}
else if (value is IDictionary<string, object>)
{
new DynamicJsonObject((IDictionary<string, object>)value).ToString(sb);
}
else if (value is ArrayList)
{
sb.Append(name + ":[");
var firstInArray = true;
foreach (var arrayValue in (ArrayList)value)
{
if (!firstInArray)
sb.Append(",");
firstInArray = false;
if (arrayValue is IDictionary<string, object>)
new DynamicJsonObject((IDictionary<string, object>)arrayValue).ToString(sb);
else if (arrayValue is string)
sb.AppendFormat("\"{0}\"", arrayValue);
else
sb.AppendFormat("{0}", arrayValue);
}
sb.Append("]");
}
else
{
sb.AppendFormat("{0}:{1}", name, value);
}
}
sb.Append("}");
}
public override bool TryGetMember(GetMemberBinder binder, out object result)
{
if (!_dictionary.TryGetValue(binder.Name, out result))
{
// return null to avoid exception. caller can check for null this way...
result = null;
return true;
}
result = WrapResultObject(result);
return true;
}
public override bool TryGetIndex(GetIndexBinder binder, object[] indexes, out object result)
{
if (indexes.Length == 1 && indexes[0] != null)
{
if (!_dictionary.TryGetValue(indexes[0].ToString(), out result))
{
// return null to avoid exception. caller can check for null this way...
result = null;
return true;
}
result = WrapResultObject(result);
return true;
}
return base.TryGetIndex(binder, indexes, out result);
}
private static object WrapResultObject(object result)
{
var dictionary = result as IDictionary<string, object>;
if (dictionary != null)
return new DynamicJsonObject(dictionary);
var arrayList = result as ArrayList;
if (arrayList != null && arrayList.Count > 0)
{
return arrayList[0] is IDictionary<string, object>
? new List<object>(arrayList.Cast<IDictionary<string, object>>().Select(x => new DynamicJsonObject(x)))
: new List<object>(arrayList.Cast<object>());
}
return result;
}
}
#endregion
}
You can use it like this:
string json = ...;
var serializer = new JavaScriptSerializer();
serializer.RegisterConverters(new[] { new DynamicJsonConverter() });
dynamic obj = serializer.Deserialize(json, typeof(object));
So, given a JSON string:
{
"Items":[
{ "Name":"Apple", "Price":12.3 },
{ "Name":"Grape", "Price":3.21 }
],
"Date":"21/11/2010"
}
The following code will work at runtime:
dynamic data = serializer.Deserialize(json, typeof(object));
data.Date; // "21/11/2010"
data.Items.Count; // 2
data.Items[0].Name; // "Apple"
data.Items[0].Price; // 12.3 (as a decimal)
data.Items[1].Name; // "Grape"
data.Items[1].Price; // 3.21 (as a decimal)
It's pretty simple using Json.NET:
dynamic stuff = JsonConvert.DeserializeObject("{ 'Name': 'Jon Smith', 'Address': { 'City': 'New York', 'State': 'NY' }, 'Age': 42 }");
string name = stuff.Name;
string address = stuff.Address.City;
Also using Newtonsoft.Json.Linq:
dynamic stuff = JObject.Parse("{ 'Name': 'Jon Smith', 'Address': { 'City': 'New York', 'State': 'NY' }, 'Age': 42 }");
string name = stuff.Name;
string address = stuff.Address.City;
Documentation: Querying JSON with dynamic
You can do this using System.Web.Helpers.Json - its Decode method returns a dynamic object which you can traverse as you like.
It's included in the System.Web.Helpers assembly (.NET 4.0).
var dynamicObject = Json.Decode(jsonString);
.NET 4.0 has a built-in library to do this:
using System.Web.Script.Serialization;
JavaScriptSerializer jss = new JavaScriptSerializer();
var d = jss.Deserialize<dynamic>(str);
This is the simplest way.
Simple "string JSON data" to object without any third-party DLL file:
WebClient client = new WebClient();
string getString = client.DownloadString("https://graph.facebook.com/zuck");
JavaScriptSerializer serializer = new JavaScriptSerializer();
dynamic item = serializer.Deserialize<object>(getString);
string name = item["name"];
//note: JavaScriptSerializer in this namespaces
//System.Web.Script.Serialization.JavaScriptSerializer
Note: You can also using your custom object.
Personel item = serializer.Deserialize<Personel>(getString);
You can achieve that with the help of Newtonsoft.Json. Install it from NuGet and then:
using Newtonsoft.Json;
dynamic results = JsonConvert.DeserializeObject<dynamic>(YOUR_JSON);
JsonFx can deserialize JSON content into dynamic objects.
Serialize to/from dynamic types (default for .NET 4.0):
var reader = new JsonReader(); var writer = new JsonWriter();
string input = #"{ ""foo"": true, ""array"": [ 42, false, ""Hello!"", null ] }";
dynamic output = reader.Read(input);
Console.WriteLine(output.array[0]); // 42
string json = writer.Write(output);
Console.WriteLine(json); // {"foo":true,"array":[42,false,"Hello!",null]}
Another way using Newtonsoft.Json:
dynamic stuff = Newtonsoft.Json.JsonConvert.DeserializeObject("{ color: 'red', value: 5 }");
string color = stuff.color;
int value = stuff.value;
I came here to find an answer for .NET Core, without any third-party or additional references. It works fine if you use ExpandoObject with the standard JsonSerializer class. Here is the example that worked for me:
using System.Text.Json;
using System.Dynamic;
dynamic json = JsonSerializer.Deserialize<ExpandoObject>(jsonText);
Console.WriteLine(json.name);
This code prints out the string value of a name property that exists within the JSON text passed into the Deserialize method. Voila - no additional libraries, no nothing. Just .NET core.
Edit: May have a problem for several levels of json with nested elements. Worked for a single-level flat object.
I made a new version of the DynamicJsonConverter that uses Expando Objects. I used expando objects, because I wanted to Serialize the dynamic back into JSON using Json.NET.
using System;
using System.Collections;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Dynamic;
using System.Web.Script.Serialization;
public static class DynamicJson
{
public static dynamic Parse(string json)
{
JavaScriptSerializer jss = new JavaScriptSerializer();
jss.RegisterConverters(new JavaScriptConverter[] { new DynamicJsonConverter() });
dynamic glossaryEntry = jss.Deserialize(json, typeof(object)) as dynamic;
return glossaryEntry;
}
class DynamicJsonConverter : JavaScriptConverter
{
public override object Deserialize(IDictionary<string, object> dictionary, Type type, JavaScriptSerializer serializer)
{
if (dictionary == null)
throw new ArgumentNullException("dictionary");
var result = ToExpando(dictionary);
return type == typeof(object) ? result : null;
}
private static ExpandoObject ToExpando(IDictionary<string, object> dictionary)
{
var result = new ExpandoObject();
var dic = result as IDictionary<String, object>;
foreach (var item in dictionary)
{
var valueAsDic = item.Value as IDictionary<string, object>;
if (valueAsDic != null)
{
dic.Add(item.Key, ToExpando(valueAsDic));
continue;
}
var arrayList = item.Value as ArrayList;
if (arrayList != null && arrayList.Count > 0)
{
dic.Add(item.Key, ToExpando(arrayList));
continue;
}
dic.Add(item.Key, item.Value);
}
return result;
}
private static ArrayList ToExpando(ArrayList obj)
{
ArrayList result = new ArrayList();
foreach (var item in obj)
{
var valueAsDic = item as IDictionary<string, object>;
if (valueAsDic != null)
{
result.Add(ToExpando(valueAsDic));
continue;
}
var arrayList = item as ArrayList;
if (arrayList != null && arrayList.Count > 0)
{
result.Add(ToExpando(arrayList));
continue;
}
result.Add(item);
}
return result;
}
public override IDictionary<string, object> Serialize(object obj, JavaScriptSerializer serializer)
{
throw new NotImplementedException();
}
public override IEnumerable<Type> SupportedTypes
{
get { return new ReadOnlyCollection<Type>(new List<Type>(new[] { typeof(object) })); }
}
}
}
Creating dynamic objects with Newtonsoft.Json works really great.
//json is your string containing the JSON value
dynamic data = JsonConvert.DeserializeObject<dynamic>(json);
Now you can access the data object just like if it was a regular object. This is the JSON object we currently have as an example:
{ "ID":123,"Name":"Jack","Numbers":[1, 2, 3] }
This is how you access it after deserialization:
data.ID //Retrieve the int
data.Name //Retrieve the string
data.Numbers[0] //Retrieve the first element in the array
I use http://json2csharp.com/ to get a class representing the JSON object.
Input:
{
"name":"John",
"age":31,
"city":"New York",
"Childs":[
{
"name":"Jim",
"age":11
},
{
"name":"Tim",
"age":9
}
]
}
Output:
public class Child
{
public string name { get; set; }
public int age { get; set; }
}
public class Person
{
public string name { get; set; }
public int age { get; set; }
public string city { get; set; }
public List<Child> Childs { get; set; }
}
After that I use Newtonsoft.Json to fill the class:
using Newtonsoft.Json;
namespace GitRepositoryCreator.Common
{
class JObjects
{
public static string Get(object p_object)
{
return JsonConvert.SerializeObject(p_object);
}
internal static T Get<T>(string p_object)
{
return JsonConvert.DeserializeObject<T>(p_object);
}
}
}
You can call it like this:
Person jsonClass = JObjects.Get<Person>(stringJson);
string stringJson = JObjects.Get(jsonClass);
PS:
If your JSON variable name is not a valid C# name (name starts with $) you can fix that like this:
public class Exception
{
[JsonProperty(PropertyName = "$id")]
public string id { get; set; }
public object innerException { get; set; }
public string message { get; set; }
public string typeName { get; set; }
public string typeKey { get; set; }
public int errorCode { get; set; }
public int eventId { get; set; }
}
The simplest way is:
Just include this DLL file.
Use the code like this:
dynamic json = new JDynamic("{a:'abc'}");
// json.a is a string "abc"
dynamic json = new JDynamic("{a:3.1416}");
// json.a is 3.1416m
dynamic json = new JDynamic("{a:1}");
// json.a is
dynamic json = new JDynamic("[1,2,3]");
/json.Length/json.Count is 3
// And you can use json[0]/ json[2] to get the elements
dynamic json = new JDynamic("{a:[1,2,3]}");
//json.a.Length /json.a.Count is 3.
// And you can use json.a[0]/ json.a[2] to get the elements
dynamic json = new JDynamic("[{b:1},{c:1}]");
// json.Length/json.Count is 2.
// And you can use the json[0].b/json[1].c to get the num.
Another option is to "Paste JSON as classes" so it can be deserialised quick and easy.
Simply copy your entire JSON
In Visual Studio: Click Edit → Paste Special → Paste JSON as classes
Here is a better explanation n piccas... ‘Paste JSON As Classes’ in ASP.NET and Web Tools 2012.2 RC
You can extend the JavaScriptSerializer to recursively copy the dictionary it created to expando object(s) and then use them dynamically:
static class JavaScriptSerializerExtensions
{
public static dynamic DeserializeDynamic(this JavaScriptSerializer serializer, string value)
{
var dictionary = serializer.Deserialize<IDictionary<string, object>>(value);
return GetExpando(dictionary);
}
private static ExpandoObject GetExpando(IDictionary<string, object> dictionary)
{
var expando = (IDictionary<string, object>)new ExpandoObject();
foreach (var item in dictionary)
{
var innerDictionary = item.Value as IDictionary<string, object>;
if (innerDictionary != null)
{
expando.Add(item.Key, GetExpando(innerDictionary));
}
else
{
expando.Add(item.Key, item.Value);
}
}
return (ExpandoObject)expando;
}
}
Then you just need to having a using statement for the namespace you defined the extension in (consider just defining them in System.Web.Script.Serialization... another trick is to not use a namespace, then you don't need the using statement at all) and you can consume them like so:
var serializer = new JavaScriptSerializer();
var value = serializer.DeserializeDynamic("{ 'Name': 'Jon Smith', 'Address': { 'City': 'New York', 'State': 'NY' }, 'Age': 42 }");
var name = (string)value.Name; // Jon Smith
var age = (int)value.Age; // 42
var address = value.Address;
var city = (string)address.City; // New York
var state = (string)address.State; // NY
You can use using Newtonsoft.Json
var jRoot =
JsonConvert.DeserializeObject<dynamic>(Encoding.UTF8.GetString(resolvedEvent.Event.Data));
resolvedEvent.Event.Data is my response getting from calling core Event .
Try this:
var units = new { Name = "Phone", Color= "White" };
var jsonResponse = JsonConvert.DeserializeAnonymousType(json, units);
I am using like this in my code and it's working fine
using System.Web.Script.Serialization;
JavaScriptSerializer oJS = new JavaScriptSerializer();
RootObject oRootObject = new RootObject();
oRootObject = oJS.Deserialize<RootObject>(Your JSon String);
Look at the article I wrote on CodeProject, one that answers the question precisely:
Dynamic types with JSON.NET
There is way too much for re-posting it all here, and even less point since that article has an attachment with the key/required source file.
For that I would use JSON.NET to do the low-level parsing of the JSON stream and then build up the object hierarchy out of instances of the ExpandoObject class.
To get an ExpandoObject:
using Newtonsoft.Json;
using Newtonsoft.Json.Converters;
Container container = JsonConvert.Deserialize<Container>(jsonAsString, new ExpandoObjectConverter());
Deserializing in JSON.NET can be dynamic using the JObject class, which is included in that library. My JSON string represents these classes:
public class Foo {
public int Age {get;set;}
public Bar Bar {get;set;}
}
public class Bar {
public DateTime BDay {get;set;}
}
Now we deserialize the string WITHOUT referencing the above classes:
var dyn = JsonConvert.DeserializeObject<JObject>(jsonAsFooString);
JProperty propAge = dyn.Properties().FirstOrDefault(i=>i.Name == "Age");
if(propAge != null) {
int age = int.Parse(propAge.Value.ToString());
Console.WriteLine("age=" + age);
}
//or as a one-liner:
int myage = int.Parse(dyn.Properties().First(i=>i.Name == "Age").Value.ToString());
Or if you want to go deeper:
var propBar = dyn.Properties().FirstOrDefault(i=>i.Name == "Bar");
if(propBar != null) {
JObject o = (JObject)propBar.First();
var propBDay = o.Properties().FirstOrDefault (i => i.Name=="BDay");
if(propBDay != null) {
DateTime bday = DateTime.Parse(propBDay.Value.ToString());
Console.WriteLine("birthday=" + bday.ToString("MM/dd/yyyy"));
}
}
//or as a one-liner:
DateTime mybday = DateTime.Parse(((JObject)dyn.Properties().First(i=>i.Name == "Bar").First()).Properties().First(i=>i.Name == "BDay").Value.ToString());
See post for a complete example.
The object you want DynamicJSONObject is included in the System.Web.Helpers.dll from the ASP.NET Web Pages package, which is part of WebMatrix.
There is a lightweight JSON library for C# called SimpleJson.
It supports .NET 3.5+, Silverlight and Windows Phone 7.
It supports dynamic for .NET 4.0
It can also be installed as a NuGet package
Install-Package SimpleJson
Use DataSet(C#) with JavaScript. A simple function for creating a JSON stream with DataSet input. Create JSON content like (multi table dataset):
[[{a:1,b:2,c:3},{a:3,b:5,c:6}],[{a:23,b:45,c:35},{a:58,b:59,c:45}]]
Just client side, use eval. For example,
var d = eval('[[{a:1,b:2,c:3},{a:3,b:5,c:6}],[{a:23,b:45,c:35},{a:58,b:59,c:45}]]')
Then use:
d[0][0].a // out 1 from table 0 row 0
d[1][1].b // out 59 from table 1 row 1
// Created by Behnam Mohammadi And Saeed Ahmadian
public string jsonMini(DataSet ds)
{
int t = 0, r = 0, c = 0;
string stream = "[";
for (t = 0; t < ds.Tables.Count; t++)
{
stream += "[";
for (r = 0; r < ds.Tables[t].Rows.Count; r++)
{
stream += "{";
for (c = 0; c < ds.Tables[t].Columns.Count; c++)
{
stream += ds.Tables[t].Columns[c].ToString() + ":'" +
ds.Tables[t].Rows[r][c].ToString() + "',";
}
if (c>0)
stream = stream.Substring(0, stream.Length - 1);
stream += "},";
}
if (r>0)
stream = stream.Substring(0, stream.Length - 1);
stream += "],";
}
if (t>0)
stream = stream.Substring(0, stream.Length - 1);
stream += "];";
return stream;
}
How to parse easy JSON content with dynamic & JavaScriptSerializer
Please add reference of System.Web.Extensions and add this namespace using System.Web.Script.Serialization; at top:
public static void EasyJson()
{
var jsonText = #"{
""some_number"": 108.541,
""date_time"": ""2011-04-13T15:34:09Z"",
""serial_number"": ""SN1234""
}";
var jss = new JavaScriptSerializer();
var dict = jss.Deserialize<dynamic>(jsonText);
Console.WriteLine(dict["some_number"]);
Console.ReadLine();
}
How to parse nested & complex json with dynamic & JavaScriptSerializer
Please add reference of System.Web.Extensions and add this namespace using System.Web.Script.Serialization; at top:
public static void ComplexJson()
{
var jsonText = #"{
""some_number"": 108.541,
""date_time"": ""2011-04-13T15:34:09Z"",
""serial_number"": ""SN1234"",
""more_data"": {
""field1"": 1.0,
""field2"": ""hello""
}
}";
var jss = new JavaScriptSerializer();
var dict = jss.Deserialize<dynamic>(jsonText);
Console.WriteLine(dict["some_number"]);
Console.WriteLine(dict["more_data"]["field2"]);
Console.ReadLine();
}
I want to do this programmatically in unit tests, I do have the luxury of typing it out.
My solution is:
var dict = JsonConvert.DeserializeObject<ExpandoObject>(json) as IDictionary<string, object>;
Now I can assert that
dict.ContainsKey("ExpectedProperty");
With Cinchoo ETL - an open source library available to parse JSON into a dynamic object:
string json = #"{
""key1"": [
{
""action"": ""open"",
""timestamp"": ""2018-09-05 20:46:00"",
""url"": null,
""ip"": ""66.102.6.98""
}
]
}";
using (var p = ChoJSONReader.LoadText(json)
.WithJSONPath("$..key1")
)
{
foreach (var rec in p)
{
Console.WriteLine("Action: " + rec.action);
Console.WriteLine("Timestamp: " + rec.timestamp);
Console.WriteLine("URL: " + rec.url);
Console.WriteLine("IP address: " + rec.ip);
}
}
Output:
Action: open
Timestamp: 2018-09-05 20:46:00
URL: http://www.google.com
IP address: 66.102.6.98
Sample fiddle: https://dotnetfiddle.net/S0ehSV
For more information, please visit codeproject articles
Disclaimer: I'm the author of this library.
try this way!
JSON example:
[{
"id": 140,
"group": 1,
"text": "xxx",
"creation_date": 123456,
"created_by": "xxx#gmail.co",
"tags": ["xxxxx"]
}, {
"id": 141,
"group": 1,
"text": "xxxx",
"creation_date": 123456,
"created_by": "xxx#gmail.com",
"tags": ["xxxxx"]
}]
C# code:
var jsonString = (File.ReadAllText(Path.Combine(Directory.GetCurrentDirectory(),"delete_result.json")));
var objects = JsonConvert.DeserializeObject<dynamic>(jsonString);
foreach(var o in objects)
{
Console.WriteLine($"{o.id.ToString()}");
}
I really like System.Web.Helpers,
dynamic data = Json.Decode(json);
as it supports usage like
var val = data.Members.NumberTen;
or
var val data.Members["10"];
The reference to System.Web.Helpers.DLL is really crazy, it is not even console and desktop app friendly. Here is my attempt to extract the same functionalities as a standalone file directly from https://github.com/mono/aspnetwebstack/tree/master/src/System.Web.Helpers
(Share this as for education purpose only)
// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved. See License.txt in the project root for license information.
using System.Collections.Generic;
using System.Diagnostics;
using System.Diagnostics.CodeAnalysis;
using System.Dynamic;
using System.Linq.Expressions;
using System.Runtime.CompilerServices;
using Microsoft.CSharp.RuntimeBinder;
using System.Web.Script.Serialization;
using System.IO;
using System.Collections;
using System.Linq;
using System.Globalization;
namespace System.Web.Helpers
{
public static class Json
{
private static readonly JavaScriptSerializer _serializer = CreateSerializer();
public static string Encode(object value)
{
// Serialize our dynamic array type as an array
DynamicJsonArray jsonArray = value as DynamicJsonArray;
if (jsonArray != null)
{
return _serializer.Serialize((object[])jsonArray);
}
return _serializer.Serialize(value);
}
public static void Write(object value, TextWriter writer)
{
writer.Write(_serializer.Serialize(value));
}
public static dynamic Decode(string value)
{
return WrapObject(_serializer.DeserializeObject(value));
}
public static dynamic Decode(string value, Type targetType)
{
return WrapObject(_serializer.Deserialize(value, targetType));
}
public static T Decode<T>(string value)
{
return _serializer.Deserialize<T>(value);
}
private static JavaScriptSerializer CreateSerializer()
{
JavaScriptSerializer serializer = new JavaScriptSerializer();
serializer.RegisterConverters(new[] { new DynamicJavaScriptConverter() });
return serializer;
}
internal class DynamicJavaScriptConverter : JavaScriptConverter
{
public override IEnumerable<Type> SupportedTypes
{
get
{
yield return typeof(IDynamicMetaObjectProvider);
yield return typeof(DynamicObject);
}
}
public override object Deserialize(IDictionary<string, object> dictionary, Type type, JavaScriptSerializer serializer)
{
throw new NotSupportedException();
}
public override IDictionary<string, object> Serialize(object obj, JavaScriptSerializer serializer)
{
Dictionary<string, object> dictionary = new Dictionary<string, object>(StringComparer.OrdinalIgnoreCase);
IEnumerable<string> memberNames = DynamicHelper.GetMemberNames(obj);
foreach (string item in memberNames)
{
dictionary[item] = DynamicHelper.GetMemberValue(obj, item);
}
return dictionary;
}
}
internal static dynamic WrapObject(object value)
{
// The JavaScriptSerializer returns IDictionary<string, object> for objects
// and object[] for arrays, so we wrap those in different dynamic objects
// so we can access the object graph using dynamic
var dictionaryValues = value as IDictionary<string, object>;
if (dictionaryValues != null)
{
return new DynamicJsonObject(dictionaryValues);
}
var arrayValues = value as object[];
if (arrayValues != null)
{
return new DynamicJsonArray(arrayValues);
}
return value;
}
}
// REVIEW: Consider implementing ICustomTypeDescriptor and IDictionary<string, object>
public class DynamicJsonObject : DynamicObject
{
private readonly IDictionary<string, object> _values;
public DynamicJsonObject(IDictionary<string, object> values)
{
Debug.Assert(values != null);
_values = values.ToDictionary(p => p.Key, p => Json.WrapObject(p.Value),
StringComparer.OrdinalIgnoreCase);
}
public override bool TryConvert(ConvertBinder binder, out object result)
{
result = null;
if (binder.Type.IsAssignableFrom(_values.GetType()))
{
result = _values;
}
else
{
throw new InvalidOperationException(String.Format(CultureInfo.CurrentCulture, "HelpersResources.Json_UnableToConvertType", binder.Type));
}
return true;
}
public override bool TryGetMember(GetMemberBinder binder, out object result)
{
result = GetValue(binder.Name);
return true;
}
public override bool TrySetMember(SetMemberBinder binder, object value)
{
_values[binder.Name] = Json.WrapObject(value);
return true;
}
public override bool TrySetIndex(SetIndexBinder binder, object[] indexes, object value)
{
string key = GetKey(indexes);
if (!String.IsNullOrEmpty(key))
{
_values[key] = Json.WrapObject(value);
}
return true;
}
public override bool TryGetIndex(GetIndexBinder binder, object[] indexes, out object result)
{
string key = GetKey(indexes);
result = null;
if (!String.IsNullOrEmpty(key))
{
result = GetValue(key);
}
return true;
}
private static string GetKey(object[] indexes)
{
if (indexes.Length == 1)
{
return (string)indexes[0];
}
// REVIEW: Should this throw?
return null;
}
public override IEnumerable<string> GetDynamicMemberNames()
{
return _values.Keys;
}
private object GetValue(string name)
{
object result;
if (_values.TryGetValue(name, out result))
{
return result;
}
return null;
}
}
[SuppressMessage("Microsoft.Naming", "CA1710:IdentifiersShouldHaveCorrectSuffix", Justification = "This class isn't meant to be used directly")]
public class DynamicJsonArray : DynamicObject, IEnumerable<object>
{
private readonly object[] _arrayValues;
public DynamicJsonArray(object[] arrayValues)
{
Debug.Assert(arrayValues != null);
_arrayValues = arrayValues.Select(Json.WrapObject).ToArray();
}
public int Length
{
get { return _arrayValues.Length; }
}
public dynamic this[int index]
{
get { return _arrayValues[index]; }
set { _arrayValues[index] = Json.WrapObject(value); }
}
public override bool TryConvert(ConvertBinder binder, out object result)
{
if (_arrayValues.GetType().IsAssignableFrom(binder.Type))
{
result = _arrayValues;
return true;
}
return base.TryConvert(binder, out result);
}
public override bool TryGetMember(GetMemberBinder binder, out object result)
{
// Testing for members should never throw. This is important when dealing with
// services that return different json results. Testing for a member shouldn't throw,
// it should just return null (or undefined)
result = null;
return true;
}
public IEnumerator GetEnumerator()
{
return _arrayValues.GetEnumerator();
}
private IEnumerable<object> GetEnumerable()
{
return _arrayValues.AsEnumerable();
}
IEnumerator<object> IEnumerable<object>.GetEnumerator()
{
return GetEnumerable().GetEnumerator();
}
[SuppressMessage("Microsoft.Usage", "CA2225:OperatorOverloadsHaveNamedAlternates", Justification = "This class isn't meant to be used directly")]
public static implicit operator object[](DynamicJsonArray obj)
{
return obj._arrayValues;
}
[SuppressMessage("Microsoft.Usage", "CA2225:OperatorOverloadsHaveNamedAlternates", Justification = "This class isn't meant to be used directly")]
public static implicit operator Array(DynamicJsonArray obj)
{
return obj._arrayValues;
}
}
/// <summary>
/// Helper to evaluate different method on dynamic objects
/// </summary>
public static class DynamicHelper
{
// We must pass in "object" instead of "dynamic" for the target dynamic object because if we use dynamic, the compiler will
// convert the call to this helper into a dynamic expression, even though we don't need it to be. Since this class is internal,
// it cannot be accessed from a dynamic expression and thus we get errors.
// Dev10 Bug 914027 - Changed the first parameter from dynamic to object, see comment at top for details
public static bool TryGetMemberValue(object obj, string memberName, out object result)
{
try
{
result = GetMemberValue(obj, memberName);
return true;
}
catch (RuntimeBinderException)
{
}
catch (RuntimeBinderInternalCompilerException)
{
}
// We catch the C# specific runtime binder exceptions since we're using the C# binder in this case
result = null;
return false;
}
// Dev10 Bug 914027 - Changed the first parameter from dynamic to object, see comment at top for details
[SuppressMessage("Microsoft.Design", "CA1031:DoNotCatchGeneralExceptionTypes", Justification = "We want to swallow exceptions that happen during runtime binding")]
public static bool TryGetMemberValue(object obj, GetMemberBinder binder, out object result)
{
try
{
// VB us an instance of GetBinderAdapter that does not implement FallbackGetMemeber. This causes lookup of property expressions on dynamic objects to fail.
// Since all types are private to the assembly, we assume that as long as they belong to CSharp runtime, it is the right one.
if (typeof(Binder).Assembly.Equals(binder.GetType().Assembly))
{
// Only use the binder if its a C# binder.
result = GetMemberValue(obj, binder);
}
else
{
result = GetMemberValue(obj, binder.Name);
}
return true;
}
catch
{
result = null;
return false;
}
}
// Dev10 Bug 914027 - Changed the first parameter from dynamic to object, see comment at top for details
public static object GetMemberValue(object obj, string memberName)
{
var callSite = GetMemberAccessCallSite(memberName);
return callSite.Target(callSite, obj);
}
// Dev10 Bug 914027 - Changed the first parameter from dynamic to object, see comment at top for details
public static object GetMemberValue(object obj, GetMemberBinder binder)
{
var callSite = GetMemberAccessCallSite(binder);
return callSite.Target(callSite, obj);
}
// dynamic d = new object();
// object s = d.Name;
// The following code gets generated for this expression:
// callSite = CallSite<Func<CallSite, object, object>>.Create(Binder.GetMember(CSharpBinderFlags.None, "Name", typeof(Program), new CSharpArgumentInfo[] { CSharpArgumentInfo.Create(CSharpArgumentInfoFlags.None, null) }));
// callSite.Target(callSite, d);
// typeof(Program) is the containing type of the dynamic operation.
// Dev10 Bug 914027 - Changed the callsite's target parameter from dynamic to object, see comment at top for details
public static CallSite<Func<CallSite, object, object>> GetMemberAccessCallSite(string memberName)
{
var binder = Binder.GetMember(CSharpBinderFlags.None, memberName, typeof(DynamicHelper), new[] { CSharpArgumentInfo.Create(CSharpArgumentInfoFlags.None, null) });
return GetMemberAccessCallSite(binder);
}
// Dev10 Bug 914027 - Changed the callsite's target parameter from dynamic to object, see comment at top for details
public static CallSite<Func<CallSite, object, object>> GetMemberAccessCallSite(CallSiteBinder binder)
{
return CallSite<Func<CallSite, object, object>>.Create(binder);
}
// Dev10 Bug 914027 - Changed the first parameter from dynamic to object, see comment at top for details
public static IEnumerable<string> GetMemberNames(object obj)
{
var provider = obj as IDynamicMetaObjectProvider;
Debug.Assert(provider != null, "obj doesn't implement IDynamicMetaObjectProvider");
Expression parameter = Expression.Parameter(typeof(object));
return provider.GetMetaObject(parameter).GetDynamicMemberNames();
}
}
}

Using reflection in C# to get properties of a nested object

Given the following objects:
public class Customer {
public String Name { get; set; }
public String Address { get; set; }
}
public class Invoice {
public String ID { get; set; }
public DateTime Date { get; set; }
public Customer BillTo { get; set; }
}
I'd like to use reflection to go through the Invoice to get the Name property of a Customer. Here's what I'm after, assuming this code would work:
Invoice inv = GetDesiredInvoice(); // magic method to get an invoice
PropertyInfo info = inv.GetType().GetProperty("BillTo.Address");
Object val = info.GetValue(inv, null);
Of course, this fails since "BillTo.Address" is not a valid property of the Invoice class.
So, I tried writing a method to split the string into pieces on the period, and walk the objects looking for the final value I was interested in. It works okay, but I'm not entirely comfortable with it:
public Object GetPropValue(String name, Object obj) {
foreach (String part in name.Split('.')) {
if (obj == null) { return null; }
Type type = obj.GetType();
PropertyInfo info = type.GetProperty(part);
if (info == null) { return null; }
obj = info.GetValue(obj, null);
}
return obj;
}
Any ideas on how to improve this method, or a better way to solve this problem?
EDIT after posting, I saw a few related posts... There doesn't seem to be an answer that specifically addresses this question, however. Also, I'd still like the feedback on my implementation.
I use following method to get the values from (nested classes) properties like
"Property"
"Address.Street"
"Address.Country.Name"
public static object GetPropertyValue(object src, string propName)
{
if (src == null) throw new ArgumentException("Value cannot be null.", "src");
if (propName == null) throw new ArgumentException("Value cannot be null.", "propName");
if(propName.Contains("."))//complex type nested
{
var temp = propName.Split(new char[] { '.' }, 2);
return GetPropertyValue(GetPropertyValue(src, temp[0]), temp[1]);
}
else
{
var prop = src.GetType().GetProperty(propName);
return prop != null ? prop.GetValue(src, null) : null;
}
}
Here is the Fiddle: https://dotnetfiddle.net/PvKRH0
I know I'm a bit late to the party, and as others said, your implementation is fine
...for simple use cases.
However, I've developed a library that solves exactly that use case, Pather.CSharp.
It is also available as Nuget Package.
Its main class is Resolver with its Resolve method.
You pass it an object and the property path, and it will return the desired value.
Invoice inv = GetDesiredInvoice(); // magic method to get an invoice
var resolver = new Resolver();
object result = resolver.Resolve(inv, "BillTo.Address");
But it can also resolve more complex property paths, including array and dictionary access.
So, for example, if your Customer had multiple addresses
public class Customer {
public String Name { get; set; }
public IEnumerable<String> Addresses { get; set; }
}
you could access the second one using Addresses[1].
Invoice inv = GetDesiredInvoice(); // magic method to get an invoice
var resolver = new Resolver();
object result = resolver.Resolve(inv, "BillTo.Addresses[1]");
I actually think your logic is fine. Personally, I would probably change it around so you pass the object as the first parameter (which is more inline with PropertyInfo.GetValue, so less surprising).
I also would probably call it something more like GetNestedPropertyValue, to make it obvious that it searches down the property stack.
You have to access the ACTUAL object that you need to use reflection on. Here is what I mean:
Instead of this:
Invoice inv = GetDesiredInvoice(); // magic method to get an invoice
PropertyInfo info = inv.GetType().GetProperty("BillTo.Address");
Object val = info.GetValue(inv, null);
Do this (edited based on comment):
Invoice inv = GetDesiredInvoice(); // magic method to get an invoice
PropertyInfo info = inv.GetType().GetProperty("BillTo");
Customer cust = (Customer)info.GetValue(inv, null);
PropertyInfo info2 = cust.GetType().GetProperty("Address");
Object val = info2.GetValue(cust, null);
Look at this post for more information:
Using reflection to set a property of a property of an object
In hopes of not sounding too late to the party, I would like to add my solution:
Definitely use recursion in this situation
public static Object GetPropValue(String name, object obj, Type type)
{
var parts = name.Split('.').ToList();
var currentPart = parts[0];
PropertyInfo info = type.GetProperty(currentPart);
if (info == null) { return null; }
if (name.IndexOf(".") > -1)
{
parts.Remove(currentPart);
return GetPropValue(String.Join(".", parts), info.GetValue(obj, null), info.PropertyType);
} else
{
return info.GetValue(obj, null).ToString();
}
}
You don't explain the source of your "discomfort," but your code basically looks sound to me.
The only thing I'd question is the error handling. You return null if the code tries to traverse through a null reference or if the property name doesn't exist. This hides errors: it's hard to know whether it returned null because there's no BillTo customer, or because you misspelled it "BilTo.Address"... or because there is a BillTo customer, and its Address is null! I'd let the method crash and burn in these cases -- just let the exception escape (or maybe wrap it in a friendlier one).
Here is another implementation that will skip a nested property if it is an enumerator and continue deeper. Properties of type string are not affected by the Enumeration Check.
public static class ReflectionMethods
{
public static bool IsNonStringEnumerable(this PropertyInfo pi)
{
return pi != null && pi.PropertyType.IsNonStringEnumerable();
}
public static bool IsNonStringEnumerable(this object instance)
{
return instance != null && instance.GetType().IsNonStringEnumerable();
}
public static bool IsNonStringEnumerable(this Type type)
{
if (type == null || type == typeof(string))
return false;
return typeof(IEnumerable).IsAssignableFrom(type);
}
public static Object GetPropValue(String name, Object obj)
{
foreach (String part in name.Split('.'))
{
if (obj == null) { return null; }
if (obj.IsNonStringEnumerable())
{
var toEnumerable = (IEnumerable)obj;
var iterator = toEnumerable.GetEnumerator();
if (!iterator.MoveNext())
{
return null;
}
obj = iterator.Current;
}
Type type = obj.GetType();
PropertyInfo info = type.GetProperty(part);
if (info == null) { return null; }
obj = info.GetValue(obj, null);
}
return obj;
}
}
based on this question and on
How to know if a PropertyInfo is a collection
by Berryl
I use this in a MVC project to dynamically Order my data by simply passing the Property to sort by
Example:
result = result.OrderBy((s) =>
{
return ReflectionMethods.GetPropValue("BookingItems.EventId", s);
}).ToList();
where BookingItems is a list of objects.
> Get Nest properties e.g., Developer.Project.Name
private static System.Reflection.PropertyInfo GetProperty(object t, string PropertName)
{
if (t.GetType().GetProperties().Count(p => p.Name == PropertName.Split('.')[0]) == 0)
throw new ArgumentNullException(string.Format("Property {0}, is not exists in object {1}", PropertName, t.ToString()));
if (PropertName.Split('.').Length == 1)
return t.GetType().GetProperty(PropertName);
else
return GetProperty(t.GetType().GetProperty(PropertName.Split('.')[0]).GetValue(t, null), PropertName.Split('.')[1]);
}
if (info == null) { /* throw exception instead*/ }
I would actually throw an exception if they request a property that doesn't exist. The way you have it coded, if I call GetPropValue and it returns null, I don't know if that means the property didn't exist, or the property did exist but it's value was null.
public static string GetObjectPropertyValue(object obj, string propertyName)
{
bool propertyHasDot = propertyName.IndexOf(".") > -1;
string firstPartBeforeDot;
string nextParts = "";
if (!propertyHasDot)
firstPartBeforeDot = propertyName.ToLower();
else
{
firstPartBeforeDot = propertyName.Substring(0, propertyName.IndexOf(".")).ToLower();
nextParts = propertyName.Substring(propertyName.IndexOf(".") + 1);
}
foreach (var property in obj.GetType().GetProperties())
if (property.Name.ToLower() == firstPartBeforeDot)
if (!propertyHasDot)
if (property.GetValue(obj, null) != null)
return property.GetValue(obj, null).ToString();
else
return DefaultValue(property.GetValue(obj, null), propertyName).ToString();
else
return GetObjectPropertyValue(property.GetValue(obj, null), nextParts);
throw new Exception("Property '" + propertyName.ToString() + "' not found in object '" + obj.ToString() + "'");
}
I wanted to share my solution although it may be too late. This solution is primarily to check if the nested property exists. But it can be easily tweaked to return the property value if needed.
private static PropertyInfo _GetPropertyInfo(Type type, string propertyName)
{
//***
//*** Check if the property name is a complex nested type
//***
if (propertyName.Contains("."))
{
//***
//*** Get the first property name of the complex type
//***
var tempPropertyName = propertyName.Split(".", 2);
//***
//*** Check if the property exists in the type
//***
var prop = _GetPropertyInfo(type, tempPropertyName[0]);
if (prop != null)
{
//***
//*** Drill down to check if the nested property exists in the complex type
//***
return _GetPropertyInfo(prop.PropertyType, tempPropertyName[1]);
}
else
{
return null;
}
}
else
{
return type.GetProperty(propertyName, BindingFlags.IgnoreCase | BindingFlags.Public | BindingFlags.Instance);
}
}
I had to refer to few posts to come up with this solution. I think this will work for multiple nested property types.
My internet connection was down when I need to solve the same problem, so I had to 're-invent the wheel':
static object GetPropertyValue(Object fromObject, string propertyName)
{
Type objectType = fromObject.GetType();
PropertyInfo propInfo = objectType.GetProperty(propertyName);
if (propInfo == null && propertyName.Contains('.'))
{
string firstProp = propertyName.Substring(0, propertyName.IndexOf('.'));
propInfo = objectType.GetProperty(firstProp);
if (propInfo == null)//property name is invalid
{
throw new ArgumentException(String.Format("Property {0} is not a valid property of {1}.", firstProp, fromObject.GetType().ToString()));
}
return GetPropertyValue(propInfo.GetValue(fromObject, null), propertyName.Substring(propertyName.IndexOf('.') + 1));
}
else
{
return propInfo.GetValue(fromObject, null);
}
}
Pretty sure this solves the problem for any string you use for property name, regardless of extent of nesting, as long as everything's a property.
Based on the original code from #jheddings, I have created a extension method version with generic type and verifications:
public static T GetPropertyValue<T>(this object sourceObject, string propertyName)
{
if (sourceObject == null) throw new ArgumentNullException(nameof(sourceObject));
if (string.IsNullOrWhiteSpace(propertyName)) throw new ArgumentException(nameof(propertyName));
foreach (string currentPropertyName in propertyName.Split('.'))
{
if (string.IsNullOrWhiteSpace(currentPropertyName)) throw new InvalidOperationException($"Invalid property '{propertyName}'");
PropertyInfo propertyInfo = sourceObject.GetType().GetProperty(currentPropertyName);
if (propertyInfo == null) throw new InvalidOperationException($"Property '{currentPropertyName}' not found");
sourceObject = propertyInfo.GetValue(sourceObject);
}
return sourceObject is T result ? result : default;
}
I wrote a method that received one object type as the argument from the input and returns dictionary<string,string>
public static Dictionary<string, string> GetProperties(Type placeHolderType)
{
var result = new Dictionary<string, string>();
var properties = placeHolderType.GetProperties();
foreach (var propertyInfo in properties)
{
string name = propertyInfo.Name;
string description = GetDescriptionTitle(propertyInfo);
if (IsNonString(propertyInfo.PropertyType))
{
var list = GetProperties(propertyInfo.PropertyType);
foreach (var item in list)
{
result.Add($"{propertyInfo.PropertyType.Name}_{item.Key}", item.Value);
}
}
else
{
result.Add(name, description);
}
}
return result;
}
public static bool IsNonString(Type type)
{
if (type == null || type == typeof(string))
return false;
return typeof(IPlaceHolder).IsAssignableFrom(type);
}
private static string GetDescriptionTitle(MemberInfo memberInfo)
{
if (Attribute.GetCustomAttribute(memberInfo, typeof(DescriptionAttribute)) is DescriptionAttribute descriptionAttribute)
{
return descriptionAttribute.Description;
}
return memberInfo.Name;
}
public static object GetPropertyValue(object src, string propName)
{
if (src == null) throw new ArgumentException("Value cannot be null.", "src");
if (propName == null) throw new ArgumentException("Value cannot be null.", "propName");
var prop = src.GetType().GetProperty(propName);
if (prop != null)
{
return prop.GetValue(src, null);
}
else
{
var props = src.GetType().GetProperties();
foreach (var property in props)
{
var propInfo = src.GetType().GetProperty(property.Name);
if (propInfo != null)
{
var propVal = propInfo.GetValue(src, null);
if (src.GetType().GetProperty(property.Name).PropertyType.IsClass)
{
return GetPropertyValue(propVal, propName);
}
return propVal;
}
}
return null;
}
usage: calling part
var emp = new Employee() { Person = new Person() { FirstName = "Ashwani" } };
var val = GetPropertyValue(emp, "FirstName");
above can search the property value at any level
Try inv.GetType().GetProperty("BillTo+Address");

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