public IHttpActionResult Add(ArtistModel artist)
        {
            if (!this.ModelState.IsValid)
            {
                return BadRequest(ModelState);
            }

            Artist artistToAdd = Mapper.Map<ArtistModel, Artist>(artist);

            this.Db.Artists.Add(artistToAdd);
            this.Db.SaveChanges();
            artist.Id = artistToAdd.Id;

            return Ok(artistToAdd);
        }
        public IHttpActionResult Update(int id, ArtistModel artist)
        {
            var artistToUpdate = this.Db.Artists.Find(id);

            if (artistToUpdate == null)
            {
                return BadRequest("Artist not found!");
            }
            else if (!ModelState.IsValid)
            {
                return BadRequest(ModelState);
            }

            Mapper.Map<ArtistModel, Artist>(artist);

            this.Db.SaveChanges();

            artist = Mapper.Map<Artist, ArtistModel>(artistToUpdate);

            return Ok(artist);
        }