Tukukkk

This is probably something very basic, but I am having trouble figuring out where I am going wrong.

I am trying to grab a string from the body of a POST, but "jsonString" only shows as null. I also want to avoid using a model, but maybe this isn't possible. The piece of code that I am hitting with PostMan is this chunk:

[Route("Edit/Test")]

[HttpPost]

public void Test(int id, [FromBody] string jsonString)

{

    ...

}

Maybe it is something I am doing incorrectly with postman, but I have been trying to use "=test" (as seen in other questions asked about this topic) in the value section of the body - x-www-form-urlencoded section with the key as jsonString and nothing. I have also tried using raw - text and raw - text/plain. I get the id so I know the url is correct. Any help with this would be greatly appreciated.

PostMan is set up like this currently:

POST http://localhost:8000/Edit/Test?id=111

key = id  value = 111

Body - x-www-form-urlencoded

key = jsonString  value = "=test"

By declaring the jsonString parameter with [FromBody] you tell ASP.NET Core to use the input formatter to bind the provided JSON (or XML) to a model. So your test should work, if you provide a simple model class

public class MyModel

{

    public string Key {get; set;}

}



[Route("Edit/Test")]

[HttpPost]

public void Test(int id, [FromBody] MyModel model)

{

    ... model.Key....

}

and a sent JSON like

{

    key: "value"

}

Of course you can skip the model binding and retrieve the provided data directly by accessing HttpContext.Request in the controller. The HttpContext.Request.Body property gives you the content stream or you can access the form data via HttpContext.Request.Forms.

I personally prefer the model binding because of the type safety.

Referencing Parameter Binding in ASP.NET Web API

Using [FromBody]

To force Web API to read a simple type from the request body, add the
[FromBody] attribute to the parameter:

[Route("Edit/Test")]

[HttpPost]

public IHttpActionResult Test(int id, [FromBody] string jsonString) { ... }

In this example, Web API will use a media-type formatter to read the
value of jsonString from the request body. Here is an example client
request.

POST http://localhost:8000/Edit/Test?id=111 HTTP/1.1

User-Agent: Fiddler

Host: localhost:8000

Content-Type: application/json

Content-Length: 6



"test"

When a parameter has [FromBody], Web API uses the Content-Type header
to select a formatter. In this example, the content type is
"application/json" and the request body is a raw JSON string (not a
JSON object).

In the above example no model is needed if the data is provided in the correct format in the body.

For URL encoded a request would look like this

POST http://localhost:8000/Edit/Test?id=111 HTTP/1.1

User-Agent: Fiddler

Host: localhost:8000

Content-Type: application/x-www-form-urlencoded

Content-Length: 5



=test

When having [FromBody]attribute, the string sent should not be a raw string, but rather a JSON string as it includes the wrapping quotes:

"test"

Based on https://weblog.west-wind.com/posts/2017/Sep/14/Accepting-Raw-Request-Body-Content-in-ASPNET-Core-API-Controllers

Similar answer string value is Empty when using FromBody in asp.net web api

You are on the right track.

On your header set

Content-Type: application/x-www-form-urlencoded

The body of the POST request should be =test and nothing else. For unknown/variable strings you have to URL encode the value so that way you do not accidentally escape with an input character.

See also POST string to ASP.NET Web Api application - returns null

I know this answer is kinda old and there are some very good answers who already solve the problem.

In order to expand the issue I'd like to mention one more thing that has driven me crazy for the last 4 or 5 hours.

It is VERY VERY VERY important that your properties in your model class have the set attribute enabled.

This WILL NOT work (parameter still null):

/* Action code */

[HttpPost]

public Weird NOURLAuthenticate([FromBody] Weird form) {

    return form;

}

/* Model class code */

public class Weird {

    public string UserId {get;}

    public string UserPwd {get;}

}

This WILL work:

/* Action code */

[HttpPost]

public Weird NOURLAuthenticate([FromBody] Weird form) {

    return form;

}

/* Model class code */

public class Weird {

    public string UserId {get; set;}

    public string UserPwd {get; set;}

}