无法从内部访问Listvew.Resources视图模型的属性 [英] Unable to access viewmodel properties from inside Listvew.Resources
问题描述
我想给的SelectedItem到View绑定。但是观点并不能够访问视图模型时，它是资源块内。
当在DataContext被重新分配给孩子，为的TextBlocks而不是用户控件（NoteView）
我缺少任何绑定？
PFB修订（全部）代码和行内注释
<用户控件X：类=Konduva.View.NoteSearchView
< - 其他命名空间在这里 - >！
的xmlns：MC =http://schemas.openxmlformats.org/markup-compatibility/2006
MC：可忽略=D
的DataContext ={结合NoteSearch源= {静态资源定位器}}>
<网格和GT;
< ListView控件的ItemsSource ={结合票据}
的SelectedItem ={结合SelectedNote}>
< ListView.Resources>
<数据类型的DataTemplate ={X：类型VM：NoteViewModel}>
<&DockPanel中GT;
< TextBlock的文本={结合标题}/>
<弹出放置=右
PlacementTarget ={绑定的RelativeSource = {的RelativeSource FindAncestor，AncestorType =的ListViewItem}
ISOPEN ={绑定（ListViewItem.IsSelected）的RelativeSource = {的RelativeSource FindAncestor，AncestorType =的ListViewItem}
的DataContext ={绑定路径= DataContext的，的RelativeSource = {的RelativeSource AncestorType = {X：类型的ListView}}}>
<&StackPanel的GT;
<！ - 这是工作 - > < TextBlock的文本={结合SelectedNote.Title}/>
<！ - 这是行不通的 - > <五：NoteView的DataContext ={结合SelectedNote}/>
< / StackPanel的>
< /弹出>
< / DockPanel中>
< / DataTemplate中>
< /ListView.Resources>
< /&的ListView GT;
< /网格和GT;
< /用户控件>
NoteView：
<网格和GT;
< TextBlock的文本={结合标题}/> //这个文本不显示
< /网格和GT;
更新3
由于您使用MvvmLight：在NoteView，请尝试更改
的DataContext ={绑定注意，源= {静态资源定位器}}
到
< UserControl.Style>
<风格的TargetType =用户控件>
< setter属性=DataContext的VALUE ={绑定注意，源= {StaticResource的定位}}/>
< /样式和GT;
< /UserControl.Style>
更新2
遇到了类似的问题在几分钟前，我没有完全理解，所以我会在同一个解决方案扔在这里，看它是否有帮助。如果改成这样什么happends
<五：？NoteView的DataContext ={绑定的RelativeSource = {的RelativeSource AncestorType = { X：弹出式}}
路径= DataContext.SelectedNote}/>
更新
我无法重现此。尝试在NoteView构造函数中添加此。你到达DataContextChangedHandler当您更改在ListView选择？
公共NoteView（）
{
的InitializeComponent（）;
DependencyPropertyDescriptor DPD =
DependencyPropertyDescriptor.FromProperty（UserControl.DataContextProperty，
typeof运算（用户控件））;
如果（DPD！= NULL）
{
dpd.AddValueChanged（这一点，新的EventHandler（DataContextChangedHandler））;
}
}
无效DataContextChangedHandler（对象发件人，EventArgs五）
{
MessageBox.Show（DataContext的更改：+的DataContext）;
}
第一个答案
您DockPanel中会得到NoteViewModel作为一个DataContext，而不是ListView和，因为这是DataContext的所有童车继承每个孩子将结束与一个NoteViewModel作为DataContext的。要使用ListView控件作为你能做到这一点弹出一个DataContext。我不知道是什么的DataContext绑定了的StackPanel做的，所以我可能会失去了一些东西。
< DataTemplate中数据类型={X：类型VM：NoteViewModel}>
<&DockPanel中GT;
< TextBlock的文本={结合标题}/>
<弹出放置=右
PlacementTarget ={绑定的RelativeSource = {的RelativeSource FindAncestor，AncestorType =的ListViewItem}
ISOPEN ={绑定（ListViewItem.IsSelected）的RelativeSource = {的RelativeSource FindAncestor，AncestorType =的ListViewItem}
的DataContext ={绑定路径= DataContext的，的RelativeSource = {的RelativeSource AncestorType = {X：类型的ListView}}}>
<&StackPanel的GT;
< TextBlock的文本={结合SelectedNote.Title}/>
<&StackPanel的GT;
<五：NoteView的DataContext ={结合SelectedNote}/>
< / StackPanel的>
< / StackPanel的>
< /弹出>
< / DockPanel中>
< / DataTemplate中>
I'm trying to bind the SelectedItem to a View. But the view is not able to access the viewmodel when it is inside the Resources block. When the datacontext is re-assigned to the children, the binding works for textblocks but not for UserControl (NoteView)
Am I missing any Binding?
PFB revised(entire) code and inline comments.
<UserControl x:Class="Konduva.View.NoteSearchView"
<!-- other namespaces here -->
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
DataContext="{Binding NoteSearch, Source={StaticResource Locator}}">
<Grid>
<ListView ItemsSource="{Binding Notes}"
SelectedItem="{Binding SelectedNote}">
<ListView.Resources>
<DataTemplate DataType="{x:Type vm:NoteViewModel}">
<DockPanel>
<TextBlock Text="{Binding Title}" />
<Popup Placement="Right"
PlacementTarget="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType=ListViewItem}}"
IsOpen="{Binding (ListViewItem.IsSelected), RelativeSource={RelativeSource FindAncestor, AncestorType=ListViewItem}}"
DataContext="{Binding Path=DataContext, RelativeSource={RelativeSource AncestorType={x:Type ListView}}}">
<StackPanel>
<!-- This is working --> <TextBlock Text="{Binding SelectedNote.Title}" />
<!-- This is not working --> <v:NoteView DataContext="{Binding SelectedNote}" />
</StackPanel>
</Popup>
</DockPanel>
</DataTemplate>
</ListView.Resources>
</ListView>
</Grid>
</UserControl>
NoteView:
<Grid>
<TextBlock Text="{Binding Title}" /> // This Text is not displayed
</Grid>
Update 3 Since you're using MvvmLight: in NoteView, try changing
DataContext="{Binding Note, Source={StaticResource Locator}}"
to
<UserControl.Style>
<Style TargetType="UserControl">
<Setter Property="DataContext" Value="{Binding Note, Source={StaticResource Locator}}"/>
</Style>
</UserControl.Style>
Update 2
Encountered a similar problem a few minutes ago which I didn't fully understand so I'll throw in the same solution here to see if it helps. What happends if you change it to this?
<v:NoteView DataContext="{Binding RelativeSource={RelativeSource AncestorType={x:Type Popup}},
Path=DataContext.SelectedNote}"/>
Update
I'm unable to reproduce this. Try adding this in your NoteView constructor. Do you reach DataContextChangedHandler when you change the selection in the ListView?
public NoteView()
{
InitializeComponent();
DependencyPropertyDescriptor dpd =
DependencyPropertyDescriptor.FromProperty(UserControl.DataContextProperty,
typeof(UserControl));
if (dpd != null)
{
dpd.AddValueChanged(this, new EventHandler(DataContextChangedHandler));
}
}
void DataContextChangedHandler(object sender, EventArgs e)
{
MessageBox.Show("DataContext Changed: " + DataContext);
}
First answer
Your DockPanel will get the NoteViewModel as a DataContext and not the ListView and since this DataContext is inherited by all Childs every child will end up with a NoteViewModel as DataContext. To use the ListView as a DataContext for the Popup you can do this. I'm not sure what the DataContext Binding for the StackPanel does though, so I might be missing something here..
<DataTemplate DataType="{x:Type vm:NoteViewModel}">
<DockPanel>
<TextBlock Text="{Binding Title}" />
<Popup Placement="Right"
PlacementTarget="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType=ListViewItem}}"
IsOpen="{Binding (ListViewItem.IsSelected), RelativeSource={RelativeSource FindAncestor, AncestorType=ListViewItem}}"
DataContext="{Binding Path=DataContext, RelativeSource={RelativeSource AncestorType={x:Type ListView}}}">
<StackPanel>
<TextBlock Text="{Binding SelectedNote.Title}" />
<StackPanel>
<v:NoteView DataContext="{Binding SelectedNote}"/>
</StackPanel>
</StackPanel>
</Popup>
</DockPanel>
</DataTemplate>
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