I'm trying to validate an entity coming from an External context has not changed.
public class Employee
{
public int Id { get; set; }
public string Name { get; set; }
}
I have a method which takes in an entity which has not been loaded from the context.
public bool Validate(Employee employee)
{
using (var context = new Context())
{
return context.Entry(employee).State == EntityState.Modified;
}
}
I would like to attach and verify that the attached entity is not modified from whats in the database.
I would prefer not to manually have to iterate of the properties. Is there a way to hack around this?
No need to attach the external entity. You can use the external entity to set values of the database entity and then check the state of the latter:
public bool Validate(Employee externalEmployee)
{
using var context = new Context(); // C# 8.0
var dbEntity = context.Where(x => x.Id == externalEmployee.Id).SingleOrDefault();
if (dbEntity != null)
{
context.Entry(dbEntity).CurrentValues.SetValues(externalEmployee);
return context.Entry(dbEntity).State == EntityState.Modified;
}
return false; // Or true, depending on your semantics.
}
You can try:
public static List<string> GetChanges<T>(this T obj, T dbObj)
{
List<string> result = new List<string>();
var type = typeof(T);
foreach (var prop in type.GetProperties())
{
var newValue = prop.GetValue(obj, null);
var dbValue = prop.GetValue(dbObj, null);
if(newValue == null && dbValue != null)
{
result.Add(prop.Name);
continue;
}
if (newValue != null && dbValue == null)
{
result.Add(prop.Name);
continue;
}
if (newValue == null && dbValue == null)
continue;
if (!newValue.ToString().Equals(dbValue.ToString()))
result.Add(prop.Name);
}
return result;
}
if resultList.Count > 0, your object has changes.
In your Validate Method:
public bool Validate(Employee employee)
{
using (var context = new Context())
{
Employee dbEmployee = context.Employee.Find(employee.Id);
if(employee.GetChanges(dbEmployee).Count > 0)
return true;
return false;
}
}
It's a god workaround =D
Works for me!
So, we created this project: https://github.com/efonsecab/BlazorRestaurant
The EF Core logic for SaveChanges is extended to automatically fill the data for the auditing columns.
Logic is in the BlazorRestaurantDbContext.partial.cs file.
public partial class BlazorRestaurantDbContext
{
public override int SaveChanges()
{
ValidateAndSetDefaults();
return base.SaveChanges();
}
public override int SaveChanges(bool acceptAllChangesOnSuccess)
{
ValidateAndSetDefaults();
return base.SaveChanges(acceptAllChangesOnSuccess);
}
public override Task<int> SaveChangesAsync(bool acceptAllChangesOnSuccess, CancellationToken cancellationToken = default)
{
ValidateAndSetDefaults();
return base.SaveChangesAsync(acceptAllChangesOnSuccess, cancellationToken);
}
public override Task<int> SaveChangesAsync(CancellationToken cancellationToken = default)
{
ValidateAndSetDefaults();
return base.SaveChangesAsync(cancellationToken);
}
private void ValidateAndSetDefaults()
{
//Check https://www.bricelam.net/2016/12/13/validation-in-efcore.html
var entities = from e in ChangeTracker.Entries()
where e.State == EntityState.Added
|| e.State == EntityState.Modified
select e.Entity;
string ipAddresses = String.Empty;
string assemblyFullName = String.Empty;
string rowCretionUser = String.Empty;
if (entities.Any(p => p is IOriginatorInfo))
{
ipAddresses = String.Join(",", GetCurrentHostIPv4Addresses());
assemblyFullName = System.Reflection.Assembly.GetEntryAssembly().FullName;
if (Thread.CurrentPrincipal != null && Thread.CurrentPrincipal.Identity != null)
rowCretionUser = Thread.CurrentPrincipal.Identity.Name;
else
rowCretionUser = "Unknown";
}
foreach (var entity in entities)
{
if (entity is IOriginatorInfo)
{
IOriginatorInfo entityWithOriginator = entity as IOriginatorInfo;
if (String.IsNullOrWhiteSpace(entityWithOriginator.SourceApplication))
{
entityWithOriginator.SourceApplication = assemblyFullName;
}
if (String.IsNullOrWhiteSpace(entityWithOriginator.OriginatorIpaddress))
{
entityWithOriginator.OriginatorIpaddress = ipAddresses;
}
if (entityWithOriginator.RowCreationDateTime == DateTimeOffset.MinValue)
{
entityWithOriginator.RowCreationDateTime = DateTimeOffset.UtcNow;
}
if (String.IsNullOrWhiteSpace(entityWithOriginator.RowCreationUser))
{
try
{
entityWithOriginator.RowCreationUser = rowCretionUser;
}
catch (Exception)
{
entityWithOriginator.RowCreationUser = "Unknown";
}
}
}
var validationContext = new ValidationContext(entity);
Validator.ValidateObject(
entity,
validationContext,
validateAllProperties: true);
}
}
public static List<string> GetCurrentHostIPv4Addresses()
{
//Check https://stackoverflow.com/questions/50386546/net-core-2-x-how-to-get-the-current-active-local-network-ipv4-address
// order interfaces by speed and filter out down and loopback
// take first of the remaining
var allUpInterfaces = NetworkInterface.GetAllNetworkInterfaces()
.OrderByDescending(c => c.Speed)
.Where(c => c.NetworkInterfaceType != NetworkInterfaceType.Loopback &&
c.OperationalStatus == OperationalStatus.Up).ToList();
List<string> lstIps = new();
if (allUpInterfaces != null && allUpInterfaces.Count > 0)
{
foreach (var singleUpInterface in allUpInterfaces)
{
var props = singleUpInterface.GetIPProperties();
// get first IPV4 address assigned to this interface
var allIpV4Address = props.UnicastAddresses
.Where(c => c.Address.AddressFamily == AddressFamily.InterNetwork)
.Select(c => c.Address)
.ToList();
allIpV4Address.ForEach((IpV4Address) =>
{
lstIps.Add(IpV4Address.ToString());
});
}
}
return lstIps;
}
}
We have used this same code in other apps and works, great.
In this specific app, however, the System.Threading.Thread.CurrentPrincipal and ClaimsPrincipal.Current, are null, when the ValidateAndSetDefaults method is executed.
Even tried the following
services.Configure<JwtBearerOptions>(
JwtBearerDefaults.AuthenticationScheme, options =>
{
options.TokenValidationParameters.NameClaimType = "name";
options.Events.OnTokenValidated = (context) =>
{
System.Threading.Thread.CurrentPrincipal = context.Principal;
return Task.CompletedTask;
};
options.SaveToken = true;
});
The context.Principal does have all the data we need at this point, but we still get null reading the Thread's CurrenPrincipal object.
Any ideas how to fix it, so we can properly get the Authenticated User information in the code above, it exists in context.Principal, it is just not accesible later in the SaveChanges for EF Core.
Fixed by using Dependency Injection along with HttpContextAccesor
https://github.com/efonsecab/BlazorRestaurant/blob/main/src/BlazorRestaurantSln/BlazorRestaurant.DataAccess/Data/BlazorRestaurantDbContext.partial.cs
Is there a way to get a dynamic object from query parameters in an ASP.NET Core WebAPI controller action?
When I try the following I get queries as an empty object
public object Action([FromQuery] dynamic queries)
{
...
}
Here is a workaround of customizing a model binder to bind the query string to Dictionary type:
DynamicModelBinder
public class DynamicModelBinder:IModelBinder
{
public Task BindModelAsync(ModelBindingContext bindingContext)
{
if (bindingContext == null)
throw new ArgumentNullException(nameof(bindingContext));
var result = new Dictionary<string, dynamic> { };
var query = bindingContext.HttpContext.Request.Query;
if (query == null)
{
bindingContext.ModelState.AddModelError("QueryString", "The data is null");
return Task.CompletedTask;
}
foreach (var k in query.Keys)
{
StringValues v = string.Empty;
var flag = query.TryGetValue(k, out v);
if (flag)
{
if (v.Count > 1)
{
result.Add(k, v);
}
else {
result.Add(k, v[0]);
}
}
}
bindingContext.Result = ModelBindingResult.Success(result);
return Task.CompletedTask;
}
}
Controller
public object Action([ModelBinder(BinderType = typeof(DynamicModelBinder))]dynamic queries)
{
return queries;
}
Result
I am trying to sort a list of objects, the code in my else statements works like charm but there is a column that has nested property and that's where the problem occurs. when I try to get the value of the nested property it gives me null exception. Can you help me globalize the code so I don't have this extra if in my code?
if (e.SortExpression == "Distribution.Coder.Name")
lstActivities = lstActivities.OrderByDescending(o => (string)o.Distribution.Coder.Name).ToList();
else
lstActivities = lstActivities.OrderByDescending(o => typeof(Activity).GetProperty(e.SortExpression).GetValue(o, null)).ToList();
Just want to shared with you this code what I found. I do not remember it reference.
public static object GetPropertyValue(object obj, string name)
{
if (string.IsNullOrEmpty(name))
{
return 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;
}
And using:
GetPropertyValue(Distribution, "Coder.Name")
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");