我试图在我的Windows 8.1商店应用中的页面之间导航。我真的很接近解决方案，但无法找到能使其发挥作用的特定部分。我能够将所有不必要的数据推送到我的下一个视图，但我无法返回。
在我的导航结构中看起来有些不对劲，但我无法弄清楚是什么。
我的MainPage.xaml看起来像这样：
<common:LayoutAwarePage
x:Name="PageRoot"
x:Class="SharePointNews.View.MainPage"
DataContext="{Binding Main, Source={StaticResource Locator}}"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:common="using:SharePointNews.Common"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d">
<Page.Resources>
<x:String x:Key="ChevronGlyph"></x:String>
<CollectionViewSource
x:Name="GroupedItemsViewSource"
Source="{Binding Items}"
IsSourceGrouped="true"
ItemsPath="Items" />
<x:String x:Key="AppName">My Application</x:String>
</Page.Resources>
<Grid Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
<Grid.ChildrenTransitions>
<TransitionCollection>
<EntranceThemeTransition />
</TransitionCollection>
</Grid.ChildrenTransitions>
<Grid.RowDefinitions>
<RowDefinition Height="140" />
<RowDefinition Height="*" />
</Grid.RowDefinitions>
<GridView
x:Name="ItemGridView"
AutomationProperties.AutomationId="ItemGridView"
AutomationProperties.Name="Grouped Items"
Grid.RowSpan="2"
Padding="116,137,40,46"
ItemsSource="{Binding Source={StaticResource GroupedItemsViewSource}}"
SelectionMode="None"
IsSwipeEnabled="false"
IsItemClickEnabled="True">
<GridView.ItemTemplate>
<DataTemplate>
<Grid HorizontalAlignment="Left" Width="310" Height="210">
<Border Background="{ThemeResource ListViewItemPlaceholderBackgroundThemeBrush}">
<Image Source="{Binding Image, Converter={StaticResource SharePointImageConverter}}"
Stretch="UniformToFill" AutomationProperties.Name="{Binding Title}" />
</Border>
<StackPanel VerticalAlignment="Bottom"
Background="{ThemeResource ListViewItemOverlayBackgroundThemeBrush}">
<TextBlock Text="{Binding Title}"
Foreground="{ThemeResource ListViewItemOverlayForegroundThemeBrush}"
Style="{StaticResource TitleTextBlockStyle}" Height="60" Margin="15,0,15,0" />
</StackPanel>
</Grid>
</DataTemplate>
</GridView.ItemTemplate>
<GridView.ItemsPanel>
<ItemsPanelTemplate>
<ItemsWrapGrid GroupPadding="0,0,70,0" />
</ItemsPanelTemplate>
</GridView.ItemsPanel>
<GridView.GroupStyle>
<GroupStyle>
<GroupStyle.HeaderTemplate>
<DataTemplate>
<Grid Margin="1,0,0,6">
<Button x:Name="HeaderButton"
Foreground="{ThemeResource ApplicationHeaderForegroundThemeBrush}"
AutomationProperties.Name="Group Title"
Style="{StaticResource TextBlockButtonStyle}"
Click="HeaderButton_Click">
<StackPanel Orientation="Horizontal">
<TextBlock x:Name="HeaderTitle" Text="{Binding Title}" Margin="3,-7,10,10"
Style="{StaticResource SubheaderTextBlockStyle}"
TextWrapping="NoWrap" />
<TextBlock Text="{StaticResource ChevronGlyph}" FontFamily="Segoe UI Symbol"
Margin="0,-7,0,10" Style="{StaticResource SubheaderTextBlockStyle}"
TextWrapping="NoWrap" />
</StackPanel>
</Button>
</Grid>
</DataTemplate>
</GroupStyle.HeaderTemplate>
</GroupStyle>
</GridView.GroupStyle>
</GridView>
<!--Vertical scrolling list only used when snapped-->
<ListView
x:Name="itemListView"
AutomationProperties.AutomationId="ItemListView"
AutomationProperties.Name="Grouped Items"
Grid.Row="1"
Visibility="Collapsed"
Margin="0,-10,0,0"
Padding="10,0,0,60"
ItemsSource="{Binding Source={StaticResource GroupedItemsViewSource}}"
ItemTemplate="{StaticResource Standard80ItemTemplate}"
SelectionMode="None"
IsSwipeEnabled="false"
IsItemClickEnabled="True">
<ListView.GroupStyle>
<GroupStyle>
<GroupStyle.HeaderTemplate>
<DataTemplate>
<Grid Margin="7,7,0,0">
<Button
AutomationProperties.Name="Group Title"
Style="{StaticResource TextPrimaryButtonStyle}"
Click="HeaderButton_Click">
<StackPanel Orientation="Horizontal">
<TextBlock Text="{Binding Title}" Margin="3,-7,10,10"
Style="{StaticResource GroupHeaderTextStyle}" />
<TextBlock Text="{StaticResource ChevronGlyph}" FontFamily="Segoe UI Symbol"
Margin="0,-7,0,10" Style="{StaticResource GroupHeaderTextStyle}" />
</StackPanel>
</Button>
</Grid>
</DataTemplate>
</GroupStyle.HeaderTemplate>
</GroupStyle>
</ListView.GroupStyle>
</ListView>
<!-- Back button and page title -->
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto" />
<ColumnDefinition Width="*" />
</Grid.ColumnDefinitions>
<Button x:Name="BackButton" Click="GoBack" IsEnabled="{Binding Frame.CanGoBack, ElementName=PageRoot}"
Style="{StaticResource BackButtonStyle}" />
<TextBlock x:Name="PageTitle" Text="{StaticResource AppName}" Style="{StaticResource PageHeaderTextStyle}"
Grid.Column="1" IsHitTestVisible="false" />
</Grid>
<VisualStateManager.VisualStateGroups>
<!-- Visual states reflect the application's view state -->
<VisualStateGroup x:Name="ApplicationViewStates">
<VisualState x:Name="FullScreenLandscape" />
<VisualState x:Name="Filled" />
<!-- The entire page respects the narrower 100-pixel margin convention for portrait -->
<VisualState x:Name="FullScreenPortrait">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="BackButton"
Storyboard.TargetProperty="Style">
<DiscreteObjectKeyFrame KeyTime="0" Value="{StaticResource PortraitBackButtonStyle}" />
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="ItemGridView"
Storyboard.TargetProperty="Padding">
<DiscreteObjectKeyFrame KeyTime="0" Value="96,137,10,56" />
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<!--
The back button and title have different styles when snapped, and the list representation is substituted
for the grid displayed in all other view states
-->
<VisualState x:Name="Snapped">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="BackButton"
Storyboard.TargetProperty="Style">
<DiscreteObjectKeyFrame KeyTime="0" Value="{StaticResource SnappedBackButtonStyle}" />
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="PageTitle"
Storyboard.TargetProperty="Style">
<DiscreteObjectKeyFrame KeyTime="0" Value="{StaticResource SnappedPageHeaderTextStyle}" />
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="itemListView"
Storyboard.TargetProperty="Visibility">
<DiscreteObjectKeyFrame KeyTime="0" Value="Visible" />
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetName="ItemGridView"
Storyboard.TargetProperty="Visibility">
<DiscreteObjectKeyFrame KeyTime="0" Value="Collapsed" />
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
</VisualStateGroup>
</VisualStateManager.VisualStateGroups>
</Grid>
</common:LayoutAwarePage>
我的MainPage.xaml的代码隐藏是这样的：
public sealed partial class MainPage : LayoutAwarePage
{
public MainPage()
{
this.InitializeComponent();
}
private void HeaderButton_Click(object sender, RoutedEventArgs e)
{
NewsSite list = (NewsSite)(sender as FrameworkElement).DataContext;
((MainViewModel)DataContext).HeaderClickCommand(list);
}
}
我的MainViewModel是这样的：
public class MainViewModel : ViewModelBase
{
#region Fields
private RelayCommand _headerClickCommand;
#endregion
#region Properties
public IList<NewsSite> Items { get; set; }
#endregion
#region Public Methods
/// <summary>
/// Initializes a new instance of the MainViewModel class.
/// </summary>
public MainViewModel()
{
GetData();
}
public void HeaderClickCommand(NewsSite list)
{
var content = Window.Current.Content;
var frame = content as Frame;
if (frame != null)
{
frame.Navigate(typeof(GroupDetailPage), list);
}
Window.Current.Activate();
}
public async void GetData()
{
GroupManager GM = new GroupManager();
var groupsLoadTask = Task.Factory.StartNew(() => GM.GetGroups());
Items = await groupsLoadTask.Result;
this.RaisePropertyChanged(() => Items);
}
#endregion
#region Private Methods
#endregion
}
我的GroupDetailPage.xaml是这样的：
<common:LayoutAwarePage
x:Name="PageRoot"
x:Class="SharePointNews.View.GroupDetailPage"
DataContext="{Binding GroupDetails, Source={StaticResource Locator}}"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:SharePointNews.View"
xmlns:common="using:SharePointNews.Common"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d">
<Page.Resources>
<CollectionViewSource
x:Name="ItemsViewSource"
Source="{Binding Items}"/>
</Page.Resources>
<Grid Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
<Grid.ChildrenTransitions>
<TransitionCollection>
<EntranceThemeTransition/>
</TransitionCollection>
</Grid.ChildrenTransitions>
<Grid.RowDefinitions>
<RowDefinition Height="140"/>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<!-- Horizontal scrolling grid -->
<GridView
x:Name="ItemGridView"
AutomationProperties.AutomationId="ItemsGridView"
AutomationProperties.Name="Items"
TabIndex="1"
Grid.RowSpan="2"
Padding="116,136,116,46"
ItemsSource="{Binding Source={StaticResource ItemsViewSource}}"
SelectionMode="None"
IsSwipeEnabled="false">
<GridView.ItemTemplate>
<DataTemplate>
<Grid HorizontalAlignment="Left" Width="310" Height="210">
<Border Background="{ThemeResource ListViewItemPlaceholderBackgroundThemeBrush}">
<Image Source="{Binding Image, Converter={StaticResource SharePointImageConverter}}" Stretch="UniformToFill" AutomationProperties.Name="{Binding Title}"/>
</Border>
<StackPanel VerticalAlignment="Bottom" Background="{ThemeResource ListViewItemOverlayBackgroundThemeBrush}">
<TextBlock Text="{Binding Title}" Foreground="{ThemeResource ListViewItemOverlayForegroundThemeBrush}" Style="{StaticResource BaseTextBlockStyle}" Height="60" Margin="15,0,15,0" FontWeight="SemiBold"/>
</StackPanel>
</Grid>
</DataTemplate>
</GridView.ItemTemplate>
</GridView>
<!-- Back button and page title -->
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="120"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<Button x:Name="BackButton" Margin="39,59,39,0" Command="{Binding NavigationHelper.GoBackCommand, ElementName=pageRoot}"
Style="{StaticResource NavigationBackButtonNormalStyle}"
VerticalAlignment="Top"
AutomationProperties.Name="Back"
AutomationProperties.AutomationId="BackButton"
AutomationProperties.ItemType="Navigation Button"/>
<TextBlock x:Name="PageTitle" Text="{Binding GroupName}" Style="{StaticResource HeaderTextBlockStyle}" Grid.Column="1"
IsHitTestVisible="false" TextWrapping="NoWrap" VerticalAlignment="Bottom" Margin="0,0,30,40"/>
</Grid>
</Grid>
</common:LayoutAwarePage>
我的GroupDetailPage的背后是：
public sealed partial class GroupDetailPage : LayoutAwarePage
{
private NavigationHelper navigationHelper;
private ObservableDictionary defaultViewModel = new ObservableDictionary();
public ObservableDictionary DefaultViewModel
{
get { return this.defaultViewModel; }
}
public NavigationHelper NavigationHelper
{
get { return this.navigationHelper; }
}
public GroupDetailPage()
{
this.InitializeComponent();
this.navigationHelper = new NavigationHelper(this);
this.navigationHelper.LoadState += navigationHelper_LoadState;
}
private void navigationHelper_LoadState(object sender, LoadStateEventArgs e)
{
// TODO: Assign a bindable collection of items to this.DefaultViewModel["Items"]
NewsSite group = ((NewsSite) e.NavigationParameter);
((GroupDetailViewModel)DataContext).GetData(group);
}
#region NavigationHelper registration
protected override void OnNavigatedTo(NavigationEventArgs e)
{
navigationHelper.OnNavigatedTo(e);
}
protected override void OnNavigatedFrom(NavigationEventArgs e)
{
navigationHelper.OnNavigatedFrom(e);
}
#endregion
}
最后我的GroupDetailViewModel是这样的：
public class GroupDetailViewModel : ViewModelBase
{
#region Fields
private NewsSite _newsSite;
#endregion
#region Properties
public List<NewsItem> Items { get; set; }
public string GroupName { get; set; }
#endregion
#region Public Methods
public GroupDetailViewModel()
{
}
public async void GetData(NewsSite group)
{
_newsSite = group;
GroupName = _newsSite.Title;
Items = _newsSite.Items.ToList();
//Items = _newsSite.Items;
this.RaisePropertyChanged(() => GroupName);
this.RaisePropertyChanged(() => Items);
}
#endregion
#region Private Methods
#endregion
}
我希望有人可以帮助我。
答案 0 :(得分：6)
经过数小时的试验和错误开发后，我终于在我的代码中发现了这个错误。
在MainPage.xaml中，我将pageRoot声明为页面名称。
在GroupDetailPage.xaml中，我还将pageRoot声明为页面名称。
因此，我覆盖了pageRoot，并且无法返回。
无论如何，对于所有读者，不要忘记给你的页面一个正确且易于理解的名字！它可以防止代码中出现故障。
干杯！