NET Core Api 中收到的 Angular POST 请求为 Null

Question

Im POSTing some data via Angular 6, but my Core API keeps returning nulls:

Request:

{"id":0,"name":"test","weight":2,"frequency":2,"activityTypeModelId":3}

Response:

{id: 0, name: null, weight: 0, frequency: 0, activityTypeModelId: 0}

Controller:

[HttpPost("[action]")]
public IActionResult Add([FromForm]Model model)
{
    return new JsonResult(model);
}

Angular, using HttpClient:

add(Model: model) {
     return this.http.post(this.addUrl, model);
}

API Model:

public class Model
{
    [Key]
    public int Id { get; set; }
    [Required]
    public string Name { get; set; }
    [Required]
    public int Weight { get; set; }
    public int Frequency { get; set; }
    public int ActivityTypeModelId { get; set; }
}

TS Model:

 export class Model{
   id?: number;
   name?: string;
   weight?: number;
   frequency?: number;
   activityTypeModelId?: number;
 }

Everything works fine when I'm using Postman. I already tried with [FromBody]. Where is the problem?

Answer 1

I dont know why, but this fixed my issue:

I created a header:

 const header = new HttpHeaders()
     .set('Content-type', 'application/json');

Changed the POST function by adding a header and JSON.Stringyfy the object:

 add(model: Model): Observable<Model> {
     const body = JSON.stringify(c);
     return this.http.post<Model>(this.addUrl, body, { headers: header} );
   }

Changed [FromForm] to [FromBody] .

Adding JSON.stringify(model) in the parameters of the http.post was not working.

JSON that is working with the CORE Api:

{"name":"test","weight":2,"activityTypeModelId":15}

JSON that is not working with the CORE Api:

{name:"test",weight:2,activityTypeModelId:15}

Without the header I encountered a 415 error from the API.

Answer 2

尝试

return this.http.post(this.addUrl, JSON.stringify(model) );

Answer 3

I think that, in .NET Core 2.1 is (see https://docs.microsoft.com/en-us/aspnet/core/web-api/action-return-types?view=aspnetcore-2.1 )

HttpPost("[action]")]
//see that I put [FromBody]
public IActionResult Add([FromBody]Model model)
{
    //OK is one of several IActionResult 
    return OK(model);
}

Answer 4

I had this issue and the problem was that I was trying to bind to an interface:

[HttpPost("[action]")]
[ProducesResponseType(typeof(bool), StatusCodes.Status200OK]
public bool SaveResponse([FromBody]ISaveRequestViewModel request) =>
    Service.SaveResponse(request.Responses);

I fixed it by changing it to a class:

[HttpPost("[action]")]
[ProducesResponseType(typeof(bool), StatusCodes.Status200OK]
public bool SaveResponse([FromBody]SaveRequestViewModel request) =>
    Service.SaveResponse(request.Responses);

This model also had to use classes instead of interfaces:

public class SaveRequestViewModel
{
    public List<IQuestionResponseViewModel> Responses { get; set; }
}

Became

public class SaveRequestViewModel
{
    public List<QuestionResponseViewModel> Responses { get; set; }
}

I guess the model binder just doesn't work with interfaces.