Question

我在我的Windows Phone 8应用程序中使用此代码，我从来没有从这种方法中获得回报：

private static ObservableCollection<Product> _productList = null;
        public ObservableCollection<Product> GetProductList()
        {
            LoadProducts().Wait();
            return _productList;
        }

        public Product GetProductById(int id)
        {
            return _productList.FirstOrDefault(p => p.Id == id);
        }

        private static async Task LoadProducts()
        {
            _productList = new ObservableCollection<Product>();
            using (var client = new HttpClient())
            {
                client.BaseAddress = new Uri("http://localhost:15017/");
                client.DefaultRequestHeaders.Accept.Clear();
                client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
                //HERE I NEVER GET THE RESPONSE 
                HttpResponseMessage response = await client.GetAsync("api/products").ConfigureAwait(false);
                if (response.IsSuccessStatusCode)
                {
                    var products = await response.Content.ReadAsAsync<List<Product>>();
                    foreach (var product in products)
                    {
                        _productList.Add(new Product(){Description = product.Description, Id=product.Id, Name = product.Name});
                    }
                }
            }
        }

有人可以告诉我为什么会那样？我从我的ViewModel类运行此方法来加载数据

使用@Stephen Cleary sollution http://msdn.microsoft.com/en-us/magazine/dn605875.aspx存在一个问题：

在我的视图中，我设置了：

<ListBox Grid.Row="1" x:Name="listBox" ItemsSource="{Binding DataSource.Result}"

然后在codeBehind：

this.DataContext = new ProductViewModel();

然后在ProductViewModel中：

public AsyncTaskManager<ObservableCollection<Product>> DataSource { get; private set; }

和

this.DataSource = new AsyncTaskManager<ObservableCollection<Product>>(ProductRepository.LoadProducts());

在AsyncTaskManager中，PropertyChanged始终为null :(

从未在Windows Phone上获得等待任务异步的结果

0 个答案: