public async Task <BeislEntity> AddBeislAsync(BeislEntity beisl)
        {
            beisl.Id   = 0;
            beisl.Tags = null;
            var addedBeisl = (_jausentestContext.Beisl.Add(beisl)).Entity;
            await _jausentestContext.SaveChangesAsync();

            return(addedBeisl);
        }
        public async Task <BeislEntity> AddOrUpdateAsync(BeislEntity beisl)
        {
            //check if beisl is alreay in database
            var existingBeisl = await _jausentestContext.Beisl
                                .Include(b => b.Tags)
                                .Include(b => b.Address)
                                .FirstOrDefaultAsync(_b => _b.Id == beisl.Id);


            if (existingBeisl == null) //beisl doenst exist in db
            {
                //if we add a new beisl, we have to check the appended tags
                foreach (var tag in beisl.Tags)
                {
                    if (!_jausentestContext.Tags.AsNoTracking().Any(t => t.Name == tag.Name))
                    {
                        _jausentestContext.Add(tag);
                    }
                    else
                    {
                        _jausentestContext.Update(tag);
                    }
                }
                //after tags are save and cozy in our db, add the beisl
                _jausentestContext.Add(beisl);
            }
            else // beisl already in db
            {
                //update values of our existingBeisl
                _jausentestContext.Entry(existingBeisl).CurrentValues.SetValues(beisl);
                _jausentestContext.Entry(existingBeisl.Address).CurrentValues.SetValues(beisl.Address);

                //we have to check each appended tag if already in database
                foreach (var tag in beisl.Tags)
                {
                    //check if submitted tag is already appended to existingBeisl
                    var existingTag = existingBeisl.Tags.AsQueryable().FirstOrDefault(t => t.Name == tag.Name);

                    //if tag is new for the existingBeisl
                    if (existingTag == null)
                    {
                        //check if tag is already in db
                        var existingTagInDb = _jausentestContext.Tags.Find(tag.Name);
                        if (existingTagInDb == null)
                        {
                            //if new add to database
                            existingBeisl.Tags.Add(tag);
                        }
                        else
                        {
                            //if already exists, only add reference to existingBeisl
                            _jausentestContext.Beisl.Find(existingBeisl.Id).Tags.Add(_jausentestContext.Tags.Find(tag.Name));
                        }
                    }
                }

                //all tags which are in existingBeisl, but not in submitted beisl, will be deleted
                foreach (var tag in existingBeisl.Tags.ToList())
                {
                    if (!beisl.Tags.Any(t => t.Name == tag.Name))
                    {
                        existingBeisl.Tags.Remove(tag);
                    }
                }

                beisl = existingBeisl;
            }

            await _jausentestContext.SaveChangesAsync();

            return(beisl);
        }