Post FromBody Always Null

Question

I\'ve got a new API that I\'m building with ASP.NET Core, and I can\'t get any data POST\'ed to an endpoint.

Here\'s what the endpoint looks like:

Answer 1

Also, make sure those variables inside your parameter class are declared as Public, (or they'll just keep returning as null)..

Answer 2

Another reason for the model binding to fail (always null) is if the data type for a property doesn't match. For example here is a simple model:

public class MyService {
    public string JobId { get; set; }
    public int ServiceType {get; set;}
}

And here is some json that doesn't match:

{"JobId":1, "ServiceType":1}

I got caught with this when I was retrieving the JobId using jquery's .data function, it was automatically converting it to an int. Fixed it by using .attr function instead.

Answer 3

I know it is not related to your case, still, I am posting my answer here.

It is a silly mistake that I had done in my code. I just copied one of my Get requests and changed it to a Post request, and forgot to decorate the parameter with [FromBody]. If anyone else is having the same problem, please make sure that you are decorating the parameter with [FromBody].

[HttpPost]
public IApiResponse Update([FromBody] User user) {
    if (user == null) return new ApiBadRequestResponse(ModelState);
    return _userService.Post(user) ? new ApiOkResponse(user) : new ApiResponse(500);
}

Answer 4

If you want to send two or more models, you should use this example:

[HttpPost]
public async Task<ActionResult> addUsuario([FromBody] Newtonsoft.Json.Linq.JObject datos)
{
    Usuarios user = datos["usuario"].ToObject<Usuarios>();
    Empresas empresa = datos["empresa"].ToObject<Empresas>();
    return Json(await _srv.addUsuario(user, empresa));
}

Answer 5

You get always null because you need to encapsulate all your post variables inside only one object. Like this:

public class MyPostModel {
    public List<string> userSocs {get; set;}
    public int collegeId {get; set;}
}

and then

public async Task<IActionResult> GetStudentResults([FromBody] MyPostModel postModel)

Answer 6

If the model is null, check:

1) Where the data is sent: body, form? and based on that add the decorator to the action. For ex:

[HttpPost]
public JsonResult SaveX([FromBody]MyVM vm) { ... }

2) Check ModelState: if it's invalid the vm will not be bound so it will be null.

if (ModelState.IsValid) { ... }