public async Task <ActionResult <Ninja> > CreateNinja(Ninja ninja)
        {
            try
            {
                if (ninja == null)
                {
                    return(BadRequest());
                }

                var createdNinja = await ninjaRepository.AddNinja(ninja);

                return(CreatedAtAction(nameof(GetNinja), new { id = createdNinja.Id }, createdNinja));
            }
            catch (Exception)
            {
                return(StatusCode(StatusCodes.Status500InternalServerError,
                                  "Error posting data"));
            }
        }