.Net Core 2.1 ModelBinding not working when posting JSON

Question

I have a .net core 2.1 solution comprising a web app, an API and a bunch of libraries.

I am trying to post JSON into a controller in the web project and it is not working - it appears that the properties that I am setting in the JSON are just being set to their default values.

I have tried with and without the [FromBody] attribute and had no luck either way.

This is what I have in the controller

[HttpPost]
public async Task<JsonResult> Search([FromBody] int test)
{
    Json(new
    {
        IThinkYouPassed=test,
    });
}

Nothing out of the ordinary there.

I am posting to this using PostMan with the following body :

{
    "test":"234"
}

If i put a breakpoint in the action and hit it and I can see that the value of test is 0.

I don't have this issue with the actions in the API project so there must be something missing from the web project - some setup that needs to be done in order for this to work?

I get the same result when using jquery to post the data so Im fairly sure that the issue is with the web app rather than something I am missing in postman.

I thought that maybe the InputFormatter might not be specified but Im told that should happen automatically as part of the UseMVC extension?

Any help with this appreciated.

Answer 1

Your json is an object that contains the test field. You should change

public async Task<JsonResult> Search([FromBody] int test)

to

public async Task<JsonResult> Search([FromBody] TestDto testDto)

where TestDto.cs contains the test field

public class TestDto {
  public int Test { get; set; }
}