I would like to read a JSON string via the Newtonsoft Json library. It works fine for any basic datatype, but it does not work for a List<double> or any List for that matter.
The test application looks like the following:
static void main()
{
string jsonString = #"
{
'name': 'set1',
'Xvv': {
'parameter': 'hByT',
'values': '[1,2,3]'
}
}";
JObject Json = JObject.Parse(jsonString);
var name = Json["name"].ToString();
var data = Json["Xvv"]["values"].Value<List<double> >(); // Raises error
}
The last line throws the following exception:
System.InvalidCastException: Invalid cast from 'System.String' to 'System.Collections.Generic.List
Is there a way to access the data directly as a List<double>?
In the example JSON you've provided, values is a string. A proper JSON array would be
'values': [1,2,3]
Anyway, after changing the string to the array, .Value<List<double>>() would throw an exception, that a JArray cannot be cast to a JToken - unfortunately I do not really know, why it does not work.
However, JToken.ToObject<T> does the trick, it
Creates an instance of the specified .NET type from the JToken
(see the documentation for ToObject)
With the line
var data = Json["Xvv"]["values"].ToObject<List<double>>();
you can cast the array correctly.
If an IEnumerable would be fine for you, too, you could also use
var data = Json["Xvv"]["values"].Values<double>();
Related
I'm trying to serialize some BSON returned from MongoDB into JSON:
var bson = MongoDB.Bson.BsonDocument.Parse(#"{
""_id"": ObjectId(""5a45a64ec7fe121dfc673c6f""),
""MyOtherId"": ObjectId(""5a45a64dc7fe121dfc673c6e""),
""Blah"": ""Test""
}");
And I want to morph the ObjectID into a string so I get
"_id": "5a45a64ec7fe121dfc673c6f",
instead of
"_id": {"$oid": "5a4597a3d999f209e05df993"},
so I tried this:
var result = Newtonsoft.Json.JsonConvert.SerializeObject(bson, new Newtonsoft.Json.Bson.Converters.BsonDataObjectIdConverter());
But I get an error:
Newtonsoft.Json.JsonSerializationException: 'Error getting value from 'AsBoolean' on 'MongoDB.Bson.BsonObjectId'.'
Inner exception:
InvalidCastException: Unable to cast object of type 'MongoDB.Bson.BsonObjectId' to type 'MongoDB.Bson.BsonBoolean'.
I still get the error with the simplified version:
var result = Newtonsoft.Json.JsonConvert.SerializeObject(bson);
using Newtonsoft.Json v10.0.3 and MongoDB.Driver v2.5.0
Newtonsoft tries to read every property of an object into a Json value.
So if your object has public string Lol {get { throw new Exception}}, Newtonsoft will try to read Lol, get the exception, and will fail serializing.
Now, a Bson value has lots of properties like AsBoolean, AsString, which throw an exception if the actual value isn't what they expect. Mongo expects you to know what value is contained in the bson and access the appropriate proeprty. But since Newtonsoft tries to access all properties, you get that error.
You can work around that issue by writing a custom converter for BsonValue and passing it to Newtonsoft in the SerializationSettings. Your converter will need to call getBsonType() on the VsonValue, and then the correct AsBoolean, AsInt or whatever to get the actual value.
Can anyone tell me why I get an error when trying to output"dJson2.Type" in the code below?
string Json1= #"[{'Id':1, 'FirstName':'John', 'LastName':'Smith'}, {'Id':2, 'FirstName':'Jane', 'LastName':'Doe'}]";
dynamic dJson1= JsonConvert.DeserializeObject(Json1);
Console.WriteLine(dJson1.GetType());
Console.WriteLine(dJson1.Type);
string Json2 = #"{'Id':1, 'FirstName':'John', 'LastName':'Smith'}";
dynamic dJson2 = JsonConvert.DeserializeObject(Json2);
Console.WriteLine(dJson2.GetType());
Console.WriteLine(dJson2.Type);
The program dies on the Console.WriteLine(dJson2.Type) statement. The output of the program is...
Newtonsoft.Json.Linq.JArray
Array
Newtonsoft.Json.Linq.JObject
(should say Object here, I think)
Inspecting the local variables, dJson2 has a "Type" property with value "Object".
This is because JObject behaves similarly as System.Dynamic.ExpandoObject. Try to change your example to:
string Json2 = #"{'Id':1, 'FirstName':'John', 'LastName':'Smith'}";
dynamic dJson2 = JsonConvert.DeserializeObject(Json2);
dJson2.Type = "mynewfield";
Console.WriteLine(dJson2.GetType());
Console.WriteLine(dJson2.Type);
If you want to get property of underlying type you need to cast it (to JToken or JObject), otherwise requested property will be searched in
IDictionary<string, JToken> that JObject implements.
This example may help:
dynamic oobj = new JObject();
oobj.Type = "TEST";
Console.WriteLine(oobj.Type);
Console.WriteLine(((JObject)oobj).Type);
I have a Json(gridModel) which could be a Json array or simple Json String. I want to serialize it to a List which matches the Json. Using Newtonsoft.Json.
JArray jGridModel = JArray.Parse(gridModel);
List<ClassName> colModel = jGridModel.ToObject<List<ClassName>>();
This works fine if the gridModel is a JSON array, but if its a single JSON, it throws an error. Please assist.
Another question. Instead of converting it to List, Is there a way to convert the JSONArray to DataTable directly, please help. Thanks.
You need to check if the object generated by the code JArray jGridModel = JArray.Parse(gridModel); is a a Type of List See updated code below:
JArray jGridModel = JArray.Parse(gridModel);
// declare your output variable
List<ClassName> colmodel = new List<ClassName>();
// use var so it can accept any output type
var outputObject = jGridModel.ToObject<List<ClassName>>();
// check the type of the output
if (outputObject is ClassName){
colmodel.Add(outputObject);
}
else{
colmodel = outputObject;
}
//colmodel is your output which is always a List<ClassName> type
Is it possible to return a dynamic object from a json deserialization using json.net? I would like to do something like this:
dynamic jsonResponse = JsonConvert.Deserialize(json);
Console.WriteLine(jsonResponse.message);
Json.NET allows us to do this:
dynamic d = JObject.Parse("{number:1000, str:'string', array: [1,2,3,4,5,6]}");
Console.WriteLine(d.number);
Console.WriteLine(d.str);
Console.WriteLine(d.array.Count);
Output:
1000
string
6
Documentation here: LINQ to JSON with Json.NET
See also JObject.Parse and JArray.Parse
As of Json.NET 4.0 Release 1, there is native dynamic support:
[Test]
public void DynamicDeserialization()
{
dynamic jsonResponse = JsonConvert.DeserializeObject("{\"message\":\"Hi\"}");
jsonResponse.Works = true;
Console.WriteLine(jsonResponse.message); // Hi
Console.WriteLine(jsonResponse.Works); // True
Console.WriteLine(JsonConvert.SerializeObject(jsonResponse)); // {"message":"Hi","Works":true}
Assert.That(jsonResponse, Is.InstanceOf<dynamic>());
Assert.That(jsonResponse, Is.TypeOf<JObject>());
}
And, of course, the best way to get the current version is via NuGet.
Updated (11/12/2014) to address comments:
This works perfectly fine. If you inspect the type in the debugger you will see that the value is, in fact, dynamic. The underlying type is a JObject. If you want to control the type (like specifying ExpandoObject, then do so.
If you just deserialize to dynamic you will get a JObject back. You can get what you want by using an ExpandoObject.
var converter = new ExpandoObjectConverter();
dynamic message = JsonConvert.DeserializeObject<ExpandoObject>(jsonString, converter);
I know this is old post but JsonConvert actually has a different method so it would be
var product = new { Name = "", Price = 0 };
var jsonResponse = JsonConvert.DeserializeAnonymousType(json, product);
Yes you can do it using the JsonConvert.DeserializeObject. To do that, just simple do:
dynamic jsonResponse = JsonConvert.DeserializeObject(json);
Console.WriteLine(jsonResponse["message"]);
Note: At the time I answered this question in 2010, there was no way to deserialize without some sort of type, this allowed you to deserialize without having go define the actual class and allowed an anonymous class to be used to do the deserialization.
You need to have some sort of type to deserialize to. You could do something along the lines of:
var product = new { Name = "", Price = 0 };
dynamic jsonResponse = JsonConvert.Deserialize(json, product.GetType());
My answer is based on a solution for .NET 4.0's build in JSON serializer. Link to deserialize to anonymous types is here:
http://blogs.msdn.com/b/alexghi/archive/2008/12/22/using-anonymous-types-to-deserialize-json-data.aspx
If you use JSON.NET with old version which didn't JObject.
This is another simple way to make a dynamic object from JSON:
https://github.com/chsword/jdynamic
NuGet Install
PM> Install-Package JDynamic
Support using string index to access member like:
dynamic json = new JDynamic("{a:{a:1}}");
Assert.AreEqual(1, json["a"]["a"]);
Test Case
And you can use this util as following :
Get the value directly
dynamic json = new JDynamic("1");
//json.Value
2.Get the member in the json object
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 integer: 1
3.IEnumerable
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.
Other
dynamic json = new JDynamic("{a:{a:1} }");
//json.a.a is 1.
Yes it is possible. I have been doing that all the while.
dynamic Obj = JsonConvert.DeserializeObject(<your json string>);
It is a bit trickier for non native type. Suppose inside your Obj, there is a ClassA, and ClassB objects. They are all converted to JObject. What you need to do is:
ClassA ObjA = Obj.ObjA.ToObject<ClassA>();
ClassB ObjB = Obj.ObjB.ToObject<ClassB>();
This is the json string:
{"d":[{"numberOfRowsAdded":"26723"}]}
string json = DAO.getUploadDataSummary();
JObject uploadData = JObject.Parse(json);
string array = (string)uploadData.SelectToken("d");
How do I change the code to reader the values in 'numberOfRowsAdded?
JObject uploadData = JObject.Parse(json);
int rowsAdded = Convert.ToInt32((string)uploadData["d"][0]["numberOfRowsAdded"])
You need to cast to JArray:
string json = "{\"d\":[{\"numberOfRowsAdded\":\"26723\"}]}";
JObject parsed = JObject.Parse(json);
JArray array = (JArray) parsed["d"];
Console.WriteLine(array.Count);
You can cast your JObject as a dynamic object.
You can also cast your array to JArray object.
JObject yourObject;
//To access to the properties in "dot" notation use a dynamic object
dynamic obj = yourObject;
//Loop over the array
foreach (dynamic item in obj.d) {
var rows = (int)item.numberOfRowsAdded;
}
I played around with writing a generic method that can read any part of my json string. I tried a lot of the answers on this thread and it did not suit my need. So this is what I came up with. I use the following method in my service layer to read my configuration properties from the json string.
public T getValue<T>(string json,string jsonPropertyName)
{
var parsedResult= JObject.Parse(json);
return parsedResult.SelectToken(jsonPropertyName).ToObject<T>();
}
and this is how you would use it :
var result = service.getValue<List<string>>(json, "propertyName");
So you can use this to get specific properties within your json string and cast it to whatever you need it to be.