Post json data in body to web api - asp.net

Question

I get always null value from body why ?
I have no problem with using fiddler but postman is fail.
I have a web api like that:
[Route("api/account/GetToken/")]
[System.Web.Http.HttpPost]
public HttpResponseBody GetToken([FromBody] string value)
{
string result = value;
}
My postman data:
and header:

Answer 1

WebAPI is working as expected because you're telling it that you're sending this json object:
{ "username":"admin", "password":"admin" }
Then you're asking it to deserialize it as a string which is impossible since it's not a valid JSON string.
Solution 1:
If you want to receive the actual JSON as in the value of value will be:
value = "{ \"username\":\"admin\", \"password\":\"admin\" }"
then the string you need to set the body of the request in postman to is:
"{ \"username\":\"admin\", \"password\":\"admin\" }"
Solution 2 (I'm assuming this is what you want):
Create a C# object that matches the JSON so that WebAPI can deserialize it properly.
First create a class that matches your JSON:
public class Credentials
{
[JsonProperty("username")]
public string Username { get; set; }
[JsonProperty("password")]
public string Password { get; set; }
}
Then in your method use this:
[Route("api/account/GetToken/")]
[System.Web.Http.HttpPost]
public HttpResponseBody GetToken([FromBody] Credentials credentials)
{
string username = credentials.Username;
string password = credentials.Password;
}

Answer 2

You are posting an object and trying to bind it to a string.
Instead, create a type to represent that data:
public class Credentials
{
public string Username { get; set; }
public string Password { get; set; }
}
[Route("api/account/GetToken/")]
[System.Web.Http.HttpPost]
public HttpResponseBody GetToken([FromBody] Credentials value)
{
string result = value.Username;
}