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How to configure NewtonsoftJson with MinimalApi in .NET 6.0

I have net6.0 project with minimal api and I would like to use NetwtonsoftJson instead of built in System.Text.Json library for serialization and deserialization.
At the moment I have this configurations for JsonOptions and that works as expected
builder.Services.Configure<JsonOptions>(options =>
{
options.SerializerOptions.PropertyNamingPolicy = JsonNamingPolicy.CamelCase;
options.SerializerOptions.WriteIndented = true;
options.SerializerOptions.ReferenceHandler = ReferenceHandler.IgnoreCycles;
options.SerializerOptions.Converters.Add(new JsonStringEnumConverter(JsonNamingPolicy.CamelCase));
});
If I try to change to something equivalent that uses Newtonsoft.Json.JsonSerializerSettings like below I am not getting same behavior. Instead it looks like it uses default System.Text.Json configuration.
builder.Services.Configure<JsonSerializerSettings>(options =>
{
options.ReferenceLoopHandling = ReferenceLoopHandling.Ignore;
options.Converters.Add(
new StringEnumConverter
{
NamingStrategy = new Newtonsoft.Json.Serialization.CamelCaseNamingStrategy()
});
});
In net5.0 I know I could use this
services.AddControllers().AddNewtonsoftJson((options) => //options); // OR
services.AddMvc().AddNewtonsoftJson((options) => //options);
However, if I use it like above in my net6.0 project then I am not using anymore MinimalApi ?

From my understanding Minimal APIs rely on some conventions regarding type binding. From what I can see they search for method with next signature - ValueTask<TModel?> BindAsync(HttpContext context, ParameterInfo parameter) on the type otherwise will try to use httpContext.Request.ReadFromJsonAsync which internally uses System.Text.Json and that can't be changed, so services.Add...().AddNewtonsoftJson((options) => //options); approach will not work.
To use Newtonsoft.Json you can try next (other than directly handling request via app.MapPost("/pst", (HttpContext c) => c.Request...)):
If you have control over all your classes which needs to be deserialized using it you can inherit them all from some generic base class which will have the method with needed signature (also you can use interface with implemented static method):
public class BaseModel<TModel>
{
public static async ValueTask<TModel?> BindAsync(HttpContext context, ParameterInfo parameter)
{
if (!context.Request.HasJsonContentType())
{
throw new BadHttpRequestException(
"Request content type was not a recognized JSON content type.",
StatusCodes.Status415UnsupportedMediaType);
}
using var sr = new StreamReader(context.Request.Body);
var str = await sr.ReadToEndAsync();
return JsonConvert.DeserializeObject<TModel>(str);
}
}
And usage:
class PostParams : BaseModel<PostParams>
{
[JsonProperty("prop")]
public int MyProperty { get; set; }
}
// accepts json body {"prop": 2}
app.MapPost("/pst", (PostParams po) => po.MyProperty);
Note that BaseModel<TModel> implemenation in this example is quite naive and possibly can be improved (check out HttpRequestJsonExtensions.ReadFromJsonAsync at least).
If you don't have control over the models or don't want to inherit them from some base you can look into creating wrappers:
public class Wrapper<TModel>
{
public Wrapper(TModel? value)
{
Value = value;
}
public TModel? Value { get; }
public static async ValueTask<Wrapper<TModel>?> BindAsync(HttpContext context, ParameterInfo parameter)
{
if (!context.Request.HasJsonContentType())
{
throw new BadHttpRequestException(
"Request content type was not a recognized JSON content type.",
StatusCodes.Status415UnsupportedMediaType);
}
using var sr = new StreamReader(context.Request.Body);
var str = await sr.ReadToEndAsync();
return new Wrapper<TModel>(JsonConvert.DeserializeObject<TModel>(str));
}
}
And usage changes to:
class PostParams
{
[JsonProperty("prop")]
public int MyProperty { get; set; }
}
// accepts json body {"prop": 2}
app.MapPost("/pst", (Wrapper<PostParams> po) => po.Value.MyProperty);
Some extra useful links:
MVC model binders - by David Fowler. Though I was not able to make it work for services.AddControllers().AddNewtonsoftJson((options) => //options);
ParameterBinder - similar approach by Damian Edwards

System.Text.Json JsonSerializer: Serialization and deserialization of 'System.Type' instances are not supported

I got an error related with security when I tried to deserialize by using `System.Text.Json JsonSerializer`.
What do I want to achieve?
I want to give the user controle to transalte some records in my database, so use can follow this scenario:
1- User can choose model of my class library.
2- After selecting a class, user will select a property(filed) from this class.
3- User will get list of values of the selected property up.
4- Last step is not here right now, user can edit a certian value.
This my piece of code:
MyPage.razor.cs:
[Inject]
private IGenericHttpClient<Type> HttpClient { get; set; }
private Type SelectedType { get; set; }
// First select a class [Class library] from HTML Select
private void OnTypeChnage(ChangeEventArgs args)
{
string FullName = "My.Models." + args.Value.ToString();
// Create type of selected class
SelectedType = Assemble.GetType(FullName, false);
}
//Call api to get all fields of this class
private async Task OnPropertChange(ChangeEventArgs args)
{
var list = await
HttpClient.GetJsonAsync($"/api/{SelectedType.Name}/all");
}
GenericHttpClient.cs
public async ValueTask<List<T>> GetJsonAsync(string url)
{
using HttpResponseMessage response = await _client.GetAsync(url);
ValidateResponse(response);
var conetnt = await response.Content.ReadAsStringAsync();
//I got the error down
return JsonSerializer.Deserialize<List<T>>(conetnt, new JsonSerializerOptions() { PropertyNameCaseInsensitive=true});
}

System.Text.Json does not support Type class due to security reasons. You send the full assembly name as a string and again try to construct the Type at the client end.

public async ValueTask<List<T>> GetJsonAsync(string url) this wont even compile, due to not specify generic information on method signature.
And also, your problem would come from the content of http response, otherwise, the Deserialize step should work fine.
I copied your code and make a small block that prove it.
// Define somewhere
public class GenericHttpClient
{
public List<T> GetJsonAsync<T>()
{
var content = "[{\"TestProp\": \"This is some test\"}]";
return JsonSerializer.Deserialize<List<T>>(content, new JsonSerializerOptions() { PropertyNameCaseInsensitive=true});
}
}
public class Test
{
public string TestProp { get; set; }
}
// Test it
var test = new GenericHttpClient();
var result = test.GetJsonAsync<Test>();

Like what #Mayur Ekbote mentioned up, "System.Text.Json does not support Type class due to security reasons." I will add a solution but I don't think this solution is very efficient.
Change Type to Dynamic:
[Inject]
private IGenericHttpClient<dynamic> HttpClient { get; set; }
Use JsonElement to get the value as a string:
private async Task OnPropertChange(ChangeEventArgs args)
{
var langCode = CultureInfo.CurrentCulture.Name;
PropertyValueList.Clear();
var list = await HttpClient.GetJsonAsync($"/api/{SelectedType.Name}/all");
List<object> listValue = new List<object>();
SelectedProperty = args.Value.ToString();
string fieldName = char.ToLower(SelectedProperty[0]) + SelectedProperty.Substring(1);
foreach (var item in list)
{
//Convert object to JsonElement
var val = ((JsonElement)item).GetProperty(fieldName).GetString();
PropertyValueList.Add(val);
}
}
Why is it not efficient?
Because I got a list of value String instead of list of selected class.

Find a generic DbSet in a DbContext dynamically

I know this question has already been asked but I couldn't find an answer that satisfied me. What I am trying to do is to retrieve a particular DbSet<T> based on its type's name.
I have the following :
[assembly: System.Runtime.CompilerServices.InternalsVisibleTo("MyDllAssemblyName")]
[assembly: System.Runtime.CompilerServices.InternalsVisibleTo("MyCallingAssemblyName")]
class MyDbContext : DbContext {
public DbSet<ModelA> A { get; set; }
public DbSet<ModelB> B { get; set; }
public dynamic GetByName_SwitchTest(string name) {
switch (name) {
case "A": return A;
case "B": return B;
}
}
public dynamic GetByName_ReflectionTest(string fullname)
{
Type targetType = Type.GetType(fullname);
var model = GetType()
.GetRuntimeProperties()
.Where(o =>
o.PropertyType.IsGenericType &&
o.PropertyType.GetGenericTypeDefinition() == typeof(DbSet<>) &&
o.PropertyType.GenericTypeArguments.Contains(targetType))
.FirstOrDefault();
if (null != model)
return model.GetValue(this);
return null;
}
}
I have no trouble getting the type itself whether it is via a simple switch or reflection. I need however to return the type as a dynamic since I do not know what DbSet type it will be.
Then somewhere else in the same assembly, I use it this way :
// MyDbContext MyDbContextInstance..
var model = MyDbContextInstance.GetByName_SwitchTest("A");
var record1 = model.FirstOrDefault(); // It crashes here with RunTimeBinderException
At this point model contains an instance of a InternalDbSet<ModelA> type. From there, any use I do with the model object I get a RunTimeBinderException :
'Microsoft.Data.Entity.Internal.InternalDbSet' does not contain a definition for 'FirstOrDefault'
Investigating on the web, I found a blog post explaining that (dixit his blog) :
the reason the call to FirstOrDefault() fails is that the type
information of model is not available at runtime. The reason it's not
available is because anonymous types are not public. When the method
is returning an instance of that anonymous type, it's returning a
System.Object which references an instance of an anonymous type - a
type whose info isn't available to the main program.
And then he points that a solution :
The solution is actually quite simple. All we have to do is open up
AssemplyInfo.cs of the ClassLibrary1 project and add the following
line to it: [assembly:InternalsVisibleTo("assembly-name")]
I did try this solution on my code but it doesn't work. For info I have an asp.net 5 solution with two assemblies running on dnx dotnet46. An app and a dll containing all my models and DbContext. All the concerned calls I do are located on the dll though.
Does this solution have any chance to work ?
Am I missing something ?
Any pointers would be greatly appreciated ?
Thanks in advance
[EDIT]
I have tried to return IQueryable<dynamic> rather than dynamic and I could do the basic query model.FirstOrDefault(); but above all I'd like to be able to filter on a field too :
var record = model.FirstOrDefault(item => item.MyProperty == true);

So how did I do it when I am not aware of <T> during compile time.
First need to get the type as DbContext.Set method returns a non-generic DbSet instance for access to entities of the given type in the context and the underlying store.
public virtual DbSet Set(Type entityType)
Note here argument is the type of entity for which a set should be returned.And set for the given entity type is the return value.
var type = Assembly.GetExecutingAssembly().GetTypes().FirstOrDefault(t => t.Name == <Pass your table name>);
now once I have this type
if(type != null)
{
DbSet context = context.Set(type);
}
Or a one liner would be
DbSet mySet = context.Set(Type.GetType("<Your Entity Name>"));

*Disclaimer: This response doesn't give a stricto sensu answer to my question. It is rather a different approach to resolve my own problem. I am aware this is a specific example for a given situation that will not work for everyone. I am posting this approach in the hope it helps someone but will not mark it as the answer as I am still hoping for a real solution.
To start with, let's accept the fact that the only useful information we can get out of the current code is whether a record exists or not.. Any attempt of a dynamic queries after that would give the RuntimeBinderException.
Then let's continue with another fact; DbContext.Add(object) and DbContext.Update(object) are not template based so we can use them to save our models ( Instead of db.A.Add() or db.A.Update() )
In my own situation, no more is required to work out a procedure
Define models a little differently
To start with, I need a field that is retrievable across all my models which should obviously be a way to identify a unique record.
// IModel give me a reliable common field to all my models ( Fits my DB design maybe not yours though )
interface IModel { Guid Id { get; set; } }
// ModelA inherit IModel so that I always have access to an 'Id'
class ModelA : IModel {
public Guid Id { get; set; }
public int OtherField { get; set; }
}
// ModelB inherit IModel so that I always have access to an 'Id'
class ModelB : IModel {
public Guid Id { get; set; }
public string WhateverOtherField { get; set; }
}
Re-purpose the dynamic queries a bit to do something we know works
I haven't found a way to do smart query dynamically, so instead I know I can reliably identify a record and know if it exists or not.
class MyDbContext : DbContext {
public DbSet<ModelA> A { get; set; }
public DbSet<ModelB> B { get; set; }
// In my case, this method help me to know the next action I need to do
// The switch/case option is not pretty but might have better performance
// than Reflection. Anyhow, this is one's choice.
public bool HasRecord_SwitchTest(string name) {
switch (name) {
case "A": return A.AsNoTracking().Any(o => o.Id == id);
case "B": return B.AsNoTracking().Any(o => o.Id == id);
}
return false;
}
// In my case, this method help me to know the next action I need to do
public bool HasRecord_ReflectionTest(string fullname)
{
Type targetType = Type.GetType(fullname);
var model = GetType()
.GetRuntimeProperties()
.Where(o =>
o.PropertyType.IsGenericType &&
o.PropertyType.GetGenericTypeDefinition() == typeof(DbSet<>) &&
o.PropertyType.GenericTypeArguments.Contains(targetType))
.FirstOrDefault();
if (null != model)
return (bool)model.GetValue(this).AsNoTracking().Any(o => o.Id == id);
return false;
}
// Update and save immediately - simplified for example
public async Task<bool> UpdateDynamic(object content)
{
EntityEntry entry = Update(content, GraphBehavior.SingleObject);
return 1 == await SaveChangesAsync(true);
}
// Insert and save immediately - simplified for example
public async Task<bool> InsertDynamic(object content)
{
EntityEntry entry = Add(content, GraphBehavior.SingleObject);
return 1 == await SaveChangesAsync(true);
}
}
A little bit of plumbing to give a sense to my situation
Next, what I needed to do with that dynamic queries was a way to replicate data from a server down to my client. ( I have omitted a big chunk of the architecture to simplify this example )
class ReplicationItem
{
public ReplicationAction Action { get; set; } // = Create, Update, Delete
public string ModelName { get; set; } // Model name
public Guid Id { get; set; } // Unique identified across whole platform
}
Connecting the bits.
Now, here's the routine that connects the bits
public async void ProcessReplicationItem(ReplicationItem replicationItem)
{
using (var db = new MyDbContext())
{
// Custom method that attempts to get remote value by Model Name and Id
// This is where I get the strongly typed object
var remoteRecord = await TryGetAsync(replicationItem.ModelName, replicationItem.Id);
bool hasRemoteRecord = remoteRecord.Content != null;
// Get to know if a local copy of this record exists.
bool hasLocalRecord = db.HasRecord_ReflectionTest(replicationItem.ModelName, replicationItem.Id);
// Ensure response is valid whether it is a successful get or error is meaningful ( ie. NotFound )
if (remoteRecord.Success || remoteRecord.ResponseCode == System.Net.HttpStatusCode.NotFound)
{
switch (replicationItem.Action)
{
case ReplicationAction.Create:
{
if (hasRemoteRecord)
{
if (hasLocalRecord)
await db.UpdateDynamic(remoteRecord.Content);
else
await db.InsertDynamic(remoteRecord.Content);
}
// else - Do nothing
break;
}
case ReplicationAction.Update:
[etc...]
}
}
}
}
// Get record from server and with 'response.Content.ReadAsAsync' type it
// already to the appropriately
public static async Task<Response> TryGetAsync(ReplicationItem item)
{
if (string.IsNullOrWhiteSpace(item.ModelName))
{
throw new ArgumentException("Missing a model name", nameof(item));
}
if (item.Id == Guid.Empty)
{
throw new ArgumentException("Missing a primary key", nameof(item));
}
// This black box, just extrapolate a uri based on model name and id
// typically "api/ModelA/{the-guid}"
string uri = GetPathFromMessage(item);
using (var client = new HttpClient())
{
client.BaseAddress = new Uri("http://localhost:12345");
HttpResponseMessage response = await client.GetAsync(uri);
if (response.IsSuccessStatusCode)
{
return new Response()
{
Content = await response.Content.ReadAsAsync(Type.GetType(item.ModelName)),
Success = true,
ResponseCode = response.StatusCode
};
}
else
{
return new Response()
{
Success = false,
ResponseCode = response.StatusCode
};
}
}
}
public class Response
{
public object Content { get; set; }
public bool Success { get; set; }
public HttpStatusCode ResponseCode { get; set; }
}
ps: I am still interested in a real answer, so please keep posting for other answer if you have a real one to share.

You could use this to get the DBSet for a specific type:
public object GetByType(DbContextcontext, Type type) {
var methode = _context.GetType().GetMethod("Set", types: Type.EmptyTypes);
if (methode == null) {
return null;
}
return methode.MakeGenericMethod(type).Invoke(_context, null);
}

Can I manually hard code a JSON object to be returned by ASP.NET web API?

I'm used to doing this in Django (similar to Ruby on Rails) where in some cases I need to hard code a JSON response object for the client to be able to interpret, but I've been searching everywhere online on figuring out how to do this with ASP.NET web API and I can't find anything on this, ASP.NET web API seems to be forcing me to create a class to represent a JSON response for every URI controller.
For example, here's the only way I know for manually creating a JSON response:
1.) I first need to create the class to represent the response object
public class XYZ_JSON
{
public string PropertyName { get; set; }
public string PropertyValue { get; set; }
}
2.) Then I need to properly write up the URI controller that'll return an "XYZ_JSON" that I've just defined above:
// GET: api/ReturnJSON
public XYZ_JSON Get()
{
XYZ_JSON test = new XYZ_JSON { PropertyName = "Romulus", PropertyValue = "123123" };
return test;
}
Will result with an http response of something like:
200 OK
{"PropertyName":"Romulus", "PropertyValue":"123123"}
This whole class to JSON design pattern is cool and all, but it's not helpful and actually makes things much worse when trying to return a class as a JSON object with many classes within it such as:
public class XYZ_JSON
{
public string PropertyName { get; set; }
public string PropertyValue { get; set; }
public List<ComplexObject> objects { get; set; } // <- do not want
}
The JSON response object above isn't that complex, but for what I'm trying to accomplish I'll have to put a list of classes within a list of classes within a list of classes, and I can't develop it in this awkward way unless I spend a week on it which is just ridiculous.
I need to be able to return a JSON response in this kind of fashion:
// GET: api/ReturnJSON
public JSON_Response Get(string id)
{
// do some SQL querying here to grab the model or what have you.
if (somethingGoesWrong = true)
return {"result":"fail"}
else
return {"result":"success","value":"some value goes here"}
}
The design pattern above is what I'm trying to accomplish with ASP.NET web API, a very simply way to return a semi-hard coded JSON response object which would allow me to return very unique and dynamic responses from a single URI. There's going to be many use cases where a list of up to 8 completely unique Class objects will be returned.
Also, If what I'm trying to accomplish is the backwards way of doing things than that's fine. I've released a very successful and stable iOS application with a flawless Django backend server handling things this way perfectly without any issues.
Can someone explain to me how I can return a simple hard coded JSON response using the ASP.NET web API?
Thanks!

You can create anonymous types in C#, so you can use one of these to produce your hard-coded result. For example:
return new JsonResult
{
Data = new
{
result = "success",
value = "some value"
}
};
To clarify, the above code is for ASP.NET MVC. If you're using Web API, then you can just return the data object, or use an IHttpActionResult. The anonymous type part (the new {}) stays the same.

Use an anonymous object.
public object Get(string id)
{
// do some SQL querying here to grab the model or what have you.
if (somethingGoesWrong = true)
return new {result = "fail"}
else
return new {result = "success", value= "some value goes here"}
}

You can use a generic JObject to return your values without constructing a complete class structure as shown below
public JObject Get(int id)
{
return JsonConvert.DeserializeObject<JObject>(#"{""result"":""success"",""value"":""some value goes here""}");
}

For hard coded response, why not just do something like below. The JSON content will be returned without being surrounded by quotation marks.
public HttpResponseMessage Get()
{
string content = "Your JSON content";
return BuildResponseWithoutQuotationMarks(content);
}
private HttpResponseMessage BuildResponseWithoutQuotationMarks(string content)
{
var response = Request.CreateResponse(HttpStatusCode.OK);
response.Content = new StringContent(content);
return response;
}
private HttpResponseMessage BuildResponseWithQuotationMarks(string content)
{
var response = Request.CreateResponse(HttpStatusCode.OK, content);
return response;
}

// GET: api/ReturnJSON
public JsonResult Get()
{
return Json(new { Property1 = "Value1", Property2 = "Value2" });
}
You can return json using JsonResult class. and the Json() method takes anonymous object so you don't need to create a class.

How to unit test an Action method which returns JsonResult?

If I have a controller like this:
[HttpPost]
public JsonResult FindStuff(string query)
{
var results = _repo.GetStuff(query);
var jsonResult = results.Select(x => new
{
id = x.Id,
name = x.Foo,
type = x.Bar
}).ToList();
return Json(jsonResult);
}
Basically, I grab stuff from my repository, then project it into a List<T> of anonymous types.
How can I unit-test it?
System.Web.Mvc.JsonResult has a property called Data, but it's of type object, as we expected.
So does that mean if I want to test that the JSON object has the properties I expect ("id", "name", "type"), I have to use reflection?
EDIT:
Here's my test:
// Arrange.
const string autoCompleteQuery = "soho";
// Act.
var actionResult = _controller.FindLocations(autoCompleteQuery);
// Assert.
Assert.IsNotNull(actionResult, "No ActionResult returned from action method.");
dynamic jsonCollection = actionResult.Data;
foreach (dynamic json in jsonCollection)
{
Assert.IsNotNull(json.id,
"JSON record does not contain \"id\" required property.");
Assert.IsNotNull(json.name,
"JSON record does not contain \"name\" required property.");
Assert.IsNotNull(json.type,
"JSON record does not contain \"type\" required property.");
}
But I get a runtime error in the loop, stating "object does not contain a definition for id".
When I breakpoint, actionResult.Data is defined as a List<T> of anonymous types, so I figure if I enumerate through these, I can check the properties. Inside the loop, the object does have a property called "id" - so not sure what the issue is.

I know I'm a bit late on this guys, but I found out why the dynamic solution wasn't working:
JsonResult returns an anonymous object and these are, by default, internal, so they need to be made visible to the tests project.
Open your ASP.NET MVC application project and find AssemblyInfo.cs from folder called Properties. Open AssemblyInfo.cs and add the following line to the end of this file.
[assembly: InternalsVisibleTo("MyProject.Tests")]
Quoted from: http://weblogs.asp.net/gunnarpeipman/archive/2010/07/24/asp-net-mvc-using-dynamic-type-to-test-controller-actions-returning-jsonresult.aspx
I thought it would be nice to have this one for the record. Works like a charm

RPM, you look to be correct. I still have much to learn about dynamic and I cannot get Marc's approach to work either. So here is how I was doing it before. You may find it helpful. I just wrote a simple extension method:
public static object GetReflectedProperty(this object obj, string propertyName)
{
obj.ThrowIfNull("obj");
propertyName.ThrowIfNull("propertyName");
PropertyInfo property = obj.GetType().GetProperty(propertyName);
if (property == null)
{
return null;
}
return property.GetValue(obj, null);
}
Then I just use that to do assertions on my Json data:
JsonResult result = controller.MyAction(...);
...
Assert.That(result.Data, Is.Not.Null, "There should be some data for the JsonResult");
Assert.That(result.Data.GetReflectedProperty("page"), Is.EqualTo(page));

I'm a bit late to the party, but I created a little wrapper that lets me then use dynamic properties. As of this answer I've got this working on ASP.NET Core 1.0 RC2, but I believe if you replace resultObject.Value with resultObject.Data it should work for non-core versions.
public class JsonResultDynamicWrapper : DynamicObject
{
private readonly object _resultObject;
public JsonResultDynamicWrapper([NotNull] JsonResult resultObject)
{
if (resultObject == null) throw new ArgumentNullException(nameof(resultObject));
_resultObject = resultObject.Value;
}
public override bool TryGetMember(GetMemberBinder binder, out object result)
{
if (string.IsNullOrEmpty(binder.Name))
{
result = null;
return false;
}
PropertyInfo property = _resultObject.GetType().GetProperty(binder.Name);
if (property == null)
{
result = null;
return false;
}
result = property.GetValue(_resultObject, null);
return true;
}
}
Usage, assuming the following controller:
public class FooController : Controller
{
public IActionResult Get()
{
return Json(new {Bar = "Bar", Baz = "Baz"});
}
}
The test (xUnit):
// Arrange
var controller = new FoosController();
// Act
var result = await controller.Get();
// Assert
var resultObject = Assert.IsType<JsonResult>(result);
dynamic resultData = new JsonResultDynamicWrapper(resultObject);
Assert.Equal("Bar", resultData.Bar);
Assert.Equal("Baz", resultData.Baz);

Here's one I use, perhaps it is of use to anyone. It tests an action that returns a JSON object for use in clientside functionality. It uses Moq and FluentAssertions.
[TestMethod]
public void GetActivationcode_Should_Return_JSON_With_Filled_Model()
{
// Arrange...
ActivatiecodeController activatiecodeController = this.ActivatiecodeControllerFactory();
CodeModel model = new CodeModel { Activation = "XYZZY", Lifespan = 10000 };
this.deviceActivatieModelBuilder.Setup(x => x.GenereerNieuweActivatiecode()).Returns(model);
// Act...
var result = activatiecodeController.GetActivationcode() as JsonResult;
// Assert...
((CodeModel)result.Data).Activation.Should().Be("XYZZY");
((CodeModel)result.Data).Lifespan.Should().Be(10000);
}

I extend the solution from Matt Greer and come up with this small extension:
public static JsonResult IsJson(this ActionResult result)
{
Assert.IsInstanceOf<JsonResult>(result);
return (JsonResult) result;
}
public static JsonResult WithModel(this JsonResult result, object model)
{
var props = model.GetType().GetProperties();
foreach (var prop in props)
{
var mv = model.GetReflectedProperty(prop.Name);
var expected = result.Data.GetReflectedProperty(prop.Name);
Assert.AreEqual(expected, mv);
}
return result;
}
And i just run the unittest as this:
- Set the expected data result:
var expected = new
{
Success = false,
Message = "Name is required"
};
- Assert the result:
// Assert
result.IsJson().WithModel(expected);

My solution is to write the extension method:
using System.Reflection;
using System.Web.Mvc;
namespace Tests.Extensions
{
public static class JsonExtensions
{
public static object GetPropertyValue(this JsonResult json, string propertyName)
{
return json.Data.GetType().GetProperty(propertyName, BindingFlags.Instance | BindingFlags.Public).GetValue(json.Data, null);
}
}
}

If in the test you know what exactly the Json data result should be then you can just do something like this:
result.Data.ToString().Should().Be(new { param = value}.ToString());
P.S. This would be if you had used FluentAssertions.Mvc5 - but it shouldn't be hard to convert it to whatever testing tools you use.

This is how I assert it
foreach (var item in jsonResult.Data as dynamic) {
((int)item.Id).ShouldBe( expected Id value );
((string)item.name).ShouldBe( "expected name value" );
}

You can convert the value property of the JsonResult into an instance of a known type and then simply access it's properties.
public static class JsonResultExtensions
{
public static T ExtractType<T>(this JsonResult result)
{
var resultAsJson = JsonSerializer.Serialize(result.Value);
return JsonSerializer.Deserialize<T>(resultAsJson);
}
}
below is an example of the use of the extension method:
MyModel model = jsonResult.ExtractType<MyModel>();
Assert.True(model.Success);