public IActionResult Put(Guid id, [FromBody] CreateOrUpdateCityViewModel city)
        {
            if (id == Guid.Empty || city == null)
            {
                return(BadRequest());
            }

            var _city = _storage.GetById(id);

            _city.Name        = city.Name;
            _city.Description = city.Description;
            _city.Population  = city.Population;

            return(Ok());
        }
        public IActionResult Create([FromBody] CreateOrUpdateCityViewModel city)
        {
            if (city == null)
            {
                return(BadRequest());
            }

            if (!ModelState.IsValid)
            {
                var models = ModelState
                             .Select(pair => new ValidationErrorViewModel(pair.Key, pair.Value));

                return(BadRequest(new { Properties = models }));
            }

            var model = new City(
                city.Name,
                city.Description,
                city.Population);

            _storage.Create(model);

            return(Ok());
        }