我使用两个不同的网络客户端来提取数据以显示在我的应用程序的主页中。我想将此代码移动到 app.xaml.cs 以在用户到达主页之前下载数据。我不确定如何在主页面上为我的列表框设置项目源。这是我目前所拥有的。
Application_Launching 中的代码
private void Application_Launching( object sender, LaunchingEventArgs e)
{
// WebClient jsonGenres
WebClient jsonGenres = new WebClient();
Uri apiGenres = new Uri( "http://api.beatport.com/catalog/3/genres" );
jsonGenres.DownloadStringCompleted += newDownloadStringCompletedEventHandler (jsonGenres_GetDataCompleted);
jsonGenres.DownloadStringAsync(apiGenres);
// WebClient jsonHome
WebClient jsonHome = new WebClient();
Uri apiHome = new Uri ("http://api.beatport.com/catalog/3/beatport/home" );
jsonHome.DownloadStringCompleted += newDownloadStringCompletedEventHandler (jsonHome_GetDataCompleted);
jsonHome.DownloadStringAsync(apiHome);
}
// Deserialize genres data
public void jsonGenres_GetDataCompleted(object sender, DownloadStringCompletedEventArgs e)
{
GenresHome genresData = JsonConvert.DeserializeObject<GenresHome>(e.Result);
ViewModel.Genres = genresData.results;
//this.listGenres.ItemsSource = genresData.results;
}
// Deserialize home page data
public void jsonHome_GetDataCompleted(object sender, DownloadStringCompletedEventArgs e)
{
ReleasesHome homeData = JsonConvert.DeserializeObject<ReleasesHome>(e.Result);
const int limit = 6;
ViewModel.Releases = homeData.results.featuredReleases.Take(limit);
//this.listRelease.ItemsSource = homeData.results.featuredReleases.Take(limit);
}
和我的主页 xaml 代码。
<ListBox x:Name="listRelease" ItemsSource="{Binding ReleasesHome}" Grid.Row="0" ScrollViewer.VerticalScrollBarVisibility="Disabled" >
<ListBox.ItemsPanel>
<ItemsPanelTemplate>
<toolkit:WrapPanel Orientation="Horizontal" />
</ItemsPanelTemplate>
</ListBox.ItemsPanel>
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Vertical">
<toolkit:HubTile Source="{Binding images.large.url}" MouseLeftButtonUp="releaseSelectedHandler" Margin="10" IsFrozen="True" />
<TextBlock Text="{Binding name}" Width="173" />
<ListBox ItemsSource="{Binding artists}" Height="28" ScrollViewer.VerticalScrollBarVisibility="Disabled" >
<ListBox.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding name}" Margin="10,0,0,0" Width="173" Style="{StaticResource PhoneTextSubtleStyle}" />
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
</Grid>
</controls:PanoramaItem>
<!--Panorama item four-->
<controls:PanoramaItem x:Name="genres" Header="genres">
<!--Single line list-->
<Grid>
<ListBox x:Name="listGenres" ItemsSource="{Binding GenresHome}">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Vertical">
<TextBlock x:Name="genresTxtBlock" Text="{Binding name}" MouseLeftButtonUp="genreSelectedHandler" Margin="10,5,0,0" Style="{StaticResource PhoneTextExtraLargeStyle}" />
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
</Grid>
</controls:PanoramaItem>
感谢您的帮助。
更新
查看上面更新的代码和下面我的 ViewModel
public class MainViewModel : INotifyPropertyChanged
{
public MainViewModel()
{
}
private IEnumerable<ResultGenreHome> _genres; // backing field
public IEnumerable<ResultGenreHome> GenresHome
{
get { return _genres; }
set
{
_genres = value;
OnPropertyChanged("GenresHome");
}
}
private IEnumerable<FeaturedReleasesHome> _releases; // backing field
public IEnumerable<FeaturedReleasesHome> ReleasesHome
{
get { return _releases; }
set
{
_releases = value;
OnPropertyChanged("ReleasesHome");
}
}
private void OnPropertyChanged(string p)
{
throw new NotImplementedException();
}
public bool IsDataLoaded
{
get;
private set;
}
public void LoadData()
{
this.IsDataLoaded = true;
}
public event PropertyChangedEventHandler PropertyChanged;
private void NotifyPropertyChanged(String propertyName)
{
PropertyChangedEventHandler handler = PropertyChanged;
if (null != handler)
{
handler(this, new PropertyChangedEventArgs(propertyName));
}
}
我已经在主页后面的代码中设置了数据上下文。这是我第一次使用 ViewModel,所以我不确定我应该在这里放什么。该应用程序运行没有任何问题,但没有显示任何数据。
最佳答案
查看默认的“Windows Phone 数据绑定(bind)应用程序”Windows Phone 项目。这个项目有一个在应用程序中创建的 ViewModel,这个 ViewModel 被 MainPage 使用。 MainPage 然后使用 Binding 获取它需要的数据。您可以通过执行以下操作在应用程序的 ViewModel 中设置数据
ViewModel.Genres = genresData.results;
然后你的 xaml 看起来像
<ListBox ItemsSource="{Binding Genres}">
...
</ListBox>
为了在设置流派时更新 UI,ViewModel 中的属性必须触发 PropertyChanged 事件
private IEnumerable<Genre> _genres; // backing field
public IEnumerable<Genre> Genres
{
get { return _genres; }
set
{
_genres = value;
OnPropertyChanged("Genres");
}
}
发布部分也是如此。
关于c# - Application_Launching 中的 WP7 webclient,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/10337825/