Error: "the application completed without reading the entire request body" Angular/C#

Question

I have an error sending a string in my Angular service.

I tried to run my stored procedure when sending the string with Postman and everything works fine.

Postman:

However, when I send the string through my service it does not work.

user.service.ts:

addUser(user: string): Observable<any> {
  return this.http.post<string>('/api/user/AddUser', user)
    .pipe(catchError(this.handleError));
}

Console error:

info: Microsoft.AspNetCore.Hosting.Internal.WebHost3 Request finished in 11.3875ms 400 application/json; charset=utf-8

info: Microsoft.AspNetCore.Server.Kestrel[32] Connection id "0HLL95U87FBQE", Request id "0HLL95U87FBQE:00000003": the application completed without reading the entire request body.

Browser error:

So I do not really know what the API really gets, because the result it expects must be a string of characters.

UserController C#:

[HttpPost]
public User AddUser([FromBody]string user)
{
  return objUser.AddUser(user);
}

If you have a solution to my problem, I'm interested. Thank you in advance.

EDIT: By modifying my service like this:

const httpOptions = {
  headers: new HttpHeaders({
    'Content-Type':  'application/json'
})

addUser(user: string): Observable<any> {
    return this.http.post<User>('/api/user/AddUser', user.toString(), httpOptions)
      .pipe(catchError(this.handleError));
}

I get this new error: Knowing that A is the first letter of the first name in the string.

Answer 1

I don't see any code that affects this error, the only point comes into mind is a string or JSON object need to be stringified which is differs from the Postman. SO it's better to always stringify the request body before passing it to API.

Try this:

addUser(user: string): Observable<any> {
  const httpOptions = {
    headers: new HttpHeaders({
      'Content-Type':  'application/json'
  })

  var userName = JSON.stringify(user);  // This

  return this.http.post<user>('/api/user/AddUser', userName, httpOptions)
    .pipe(catchError(this.handleError));
}