Can`t recive POST request Asp.net core 2.2

Question

Can`t recive 3ds party POST request. 415 Unsupported Media type or empty model

On backend: Asp.net core 2.2 and Aspnetbilerplate(if its important)

request from a third-party server, so I can not influence it. I can only specify the endpoint to which requests will be sent

Looks like that: curl http://MyServer/api/MyController/MyAction -d '{"a":"a", "b":1}'

My code Dto:

    public class testDto
    {
        public string A { get; set; }
        public int B { get; set; }
    }

Controller:

[Route("api/[controller]/[action]")]
public class MyController : MyControllerBase
{
   ...
   [HttpPost]
   public async Task<testDto> MyAction(testDto dto)
   {
     //some code
     _logger.Info("test");            
   }
   ...
}

My test request from console with results:

C:\WINDOWS\system32>curl -d '{"a":"a", "b":1}' http://myServerUrl/api/MyController/MyAction
curl: (3) [globbing] unmatched close brace/bracket in column 4
{"result":{"a":null,"b":0},"targetUrl":null,"success":true,"error":null,"unAuthorizedRequest":false,"__abp":true}

Model is empty, no binding has occurred.

I am added [FromBody] to action like that:

   [HttpPost]
   public async Task<testDto> MyAction([FromBody]testDto dto)
   {
     //some code
     _logger.Info("test");            
   }

Result: HTTP status code 415

Also, try adding [FromForm] and [FromQyesry]. Result: empty model

What is the problem? How do I make it work? Thank you in advance.

Answer 1

The first thing is the request curl http://MyServer/api/MyController/MyAction -d '{"a":"a", "b":1}' is not correct , you could see the protocol use :

curl http://MyServer/api/MyController/MyAction -d '{"a":"a", "b":1}' --trace-ascii debugdump.txt

If checking the dump file , you will find the data is not completely sent :

0000: POST /api/values/MyAction HTTP/1.1
0024: Host: localhost:44348
003b: User-Agent: curl/7.55.1
0054: Accept: */*
0061: Content-Length: 6
0074: Content-Type: application/x-www-form-urlencoded
00a5: 
=> Send data, 6 bytes (0x6)
0000: '{a:a,
== Info: upload completely sent off: 6 out of 6 bytes
== Info: schannel: client wants to read 102400 bytes
== Info: schannel: encdata_buffer resized 103424
== Info: schannel: encrypted data buffer: offset 0 length 103424
== Info: schannel: encrypted data got 322
== Info: schannel: encrypted data buffer: offset 322 length 103424

You should contact with 3ds party to confirm the request .

Anyway , if default model binding doesn't meet your requirement , you can create Custom Model Binding :

1. Adding middleware to make request EnableRewind :

   app.Use(async (ctx, next) =>
   {
       ctx.Request.EnableRewind();
       await next();
   });
   

2. Create custom binder which implements IModelBinder:

   public class testDtoEntityBinder : IModelBinder
   {
       public Task BindModelAsync(ModelBindingContext bindingContext)
       {
           if (bindingContext == null)
           {
               throw new ArgumentNullException(nameof(bindingContext));
           }
   
   
           var body = bindingContext.HttpContext.Request.Body;
           body.Position = 0;
   
   
           string raw = new System.IO.StreamReader(body).ReadToEnd();
   
           //now read content from request content and fill your model 
           var result = new testDto
           {
               A = "",
               B = 1,
           };
   
   
           bindingContext.Result = ModelBindingResult.Success(result);
           return Task.CompletedTask;
       }
   }
   

3. User the binder :

   [ModelBinder(BinderType = typeof(testDtoEntityBinder))]
   public class testDto
   {
       public string A { get; set; }
       public int B { get; set; }
   }