JSON serialization/deserialization not working when migrating to ASP.Net Core MVC

Question

We are migrating a site from ASP MVC .Net Framework to .Net Core. In many cases we do ajax POST requests from the page to the Controller:

js:

var request = { Name: "bar" };
$.ajax({
    url: "/Home/foo",
    type: "POST",
    data: JSON.stringify(request),
    dataType: 'json',
    contentType: "application/json; charset=utf-8",
    success: function (response) {
        console.log();
    }
});

c# Controller:

[HttpPost]
public async Task<JsonResult> foo(FooRequest request)
{
    //request.Name is empty
    return Json(new { msg = "Success" });
}

c# Model:

public class FooRequest
{
    public string Name { get; set; }
}

This all works in .Net Framework, but fails in Core were all properties of the received object are null.

I've tried using both AddJsonOptions:

services.AddControllersWithViews()
    .AddJsonOptions(option =>
    {
        option.JsonSerializerOptions.PropertyNamingPolicy = null;
        option.JsonSerializerOptions.PropertyNameCaseInsensitive = true;
    });

...and AddNewtonsoftJson:

services.AddControllersWithViews()
    .AddNewtonsoftJson(option =>
    {
        option.SerializerSettings.ContractResolver = new Newtonsoft.Json.Serialization.DefaultContractResolver();
    });

...but none of them works.

What do I need to do to get the same behavior in .Net Core as I do in .Net Framework?

Update

I get the same behavior calling the endoint from Postman (request.Name is null):

POST /home/foo HTTP/1.1
Host: localhost:44393
Content-Type: application/json

{ "Name": "bar" }

I've also tried to serializing the request:

var request = { Name: "bar" };
$.ajax({
    url: "/Home/foo",
    type: "POST",
    data: request,
    dataType: 'json',
    contentType: "application/json; charset=utf-8",
    success: function (response) {
        console.log();
    }
});

...but with the same result

Should have been more clear, but all properties of the received object are null. — wmmhihaa
– wmmhihaa, Commented Mar 16, 2020 at 19:15
Did you check what you're POSTing? Why are you calling JSON.stringify on the object you're posting? — mason
– mason, Commented Mar 16, 2020 at 19:23
Because that was the only way to get it to work in .Net Framework. I'd be happy to change that, but I get the same issue using data:request, — wmmhihaa
– wmmhihaa, Commented Mar 16, 2020 at 19:26

Marco · Accepted Answer · 2020-03-16 19:48:31Z

3

Try adding the FromBodyAttribute to your parameter:

[HttpPost]
public async Task<JsonResult> foo([FromBody] FooRequest request)
{
    //request.Name is empty
    return Json(new { msg = "Success" });
}

You can omit this attribute, if you decorate your controller with the ApiControllerAttribute

answered Mar 16, 2020 at 19:48

Marco

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3 Comments

wmmhihaa Over a year ago

Thanks...Just one short question is there a way to set this in the Startup.cs, as I've got a lot of these type of methods (residing my normal Actions)?

Marco Over a year ago

Unfortunately no. The only "global"-ish way is to use ApiControllers for Http requests, and normal controllers for views. So if you refactor your api call inside a controller with decorated with [ApiController], you should be able to omit this.

Ian Kemp - SO dead by AI greed Over a year ago

You can probably do it with an action filter.

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JSON serialization/deserialization not working when migrating to ASP.Net Core MVC

js:

c# Controller:

c# Model:

What do I need to do to get the same behavior in .Net Core as I do in .Net Framework?

Update

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js:

c# Controller:

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What do I need to do to get the same behavior in .Net Core as I do in .Net Framework?

Update

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