How to return an action result of async Task<IEnumerable<SomeClass>>?

Question

I have this code but the controller is expecting a return type of ActionResult. Why is the controller is accepting a Task> like this return await _context.Users.ToListAsync(); (the default code when a controller is generated)?

//controller
public async Task<ActionResult<IEnumerable<User>>> GetUsers()
{
        return await _userService.GetAll();
}
//service method
public async Task<IEnumerable<User>> GetAll()
{
    return await _db.Users.ToListAsync();
}

Answer 1

I believe you need something like:

public async Task<ActionResult<IEnumerable<User>>> MyController()
{
    var res = await _userService.GetAll();

    if (res == null)
    {
        return NotFound();
    }

    return Ok(res);
}

As a side note, I recommend changing IEnumerable<> to IList<> . It's not strictly correct to return a enumerable here and you can also run into "multiple enumeration" issues.