public async Task <Street> AddStreetAsync(string street) { var findedStreet = await Streets .FirstOrDefaultAsync(m => m.StreetName.Equals(street, StringComparison.OrdinalIgnoreCase)); if (findedStreet == null) { findedStreet = new Street { StreetName = street }; await AddAsync(findedStreet); await SaveChangesAsync(); } return(findedStreet); }