Add a controller to create new Users

Let's use the code generator to make a new controller for managing users. We will keep the POST action to create a new user. Later on, we may add user management features where we need to add back in other commands like DELETE and PUT. We also do not want to expose any GET actions where someone could list all the users!

dotnet aspnet-codegenerator controller --model User -name UsersController --useAsyncActions -api --dataContext DatabaseContext --relativeFolderPath Controllers

This is the only Http method we will leave in the file:

[HttpPost]
public async Task<ActionResult<User>> PostUser(User user)
{
    // Indicate to the database context we want to add this new record
    _context.Users.Add(user);
    await _context.SaveChangesAsync();
    // Return a response that indicates the object was created (status code `201`) and some additional
    // headers with details of the newly created object.
    return CreatedAtAction("GetUser", new { id = user.Id }, user);
}