wpf 在 contentpresenter 上设置 Datacontext：在 ContentTemplate 内绑定不起作用

Setting Datacontext on contentpresenter: Binding inside ContentTemplate is not working

提问by Gilles Radrizzi

I'm learning WPF and the MVVM Pattern and I'm trying to build a calendar-like view. So I currently have a Grid with 6 rows and 7 columns. The first row should be the Header, thus specifying the Week days like 'Monday, Tuesday, etc...' I have the following right now in my MonthView.xaml

我正在学习 WPF 和 MVVM 模式，并且正在尝试构建类似日历的视图。所以我目前有一个 6 行 7 列的网格。第一行应该是标题，从而指定像“星期一、星期二等...”这样的周天我现在在我的 MonthView.xaml 中有以下内容

<Grid>
    <Grid.RowDefinitions>
        <RowDefinition Height="{Binding RowHeight}"/>
        <RowDefinition Height="{Binding RowHeight}"/>
        <RowDefinition Height="{Binding RowHeight}"/>
        <RowDefinition Height="{Binding RowHeight}"/>
        <RowDefinition Height="{Binding RowHeight}"/>
        <RowDefinition Height="{Binding RowHeight}"/>
        <RowDefinition Height="{Binding RowHeight}"/>
    </Grid.RowDefinitions>

    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="{Binding CellWidth}"/>
        <ColumnDefinition Width="{Binding CellWidth}"/>
        <ColumnDefinition Width="{Binding CellWidth}"/>
        <ColumnDefinition Width="{Binding CellWidth}"/>
        <ColumnDefinition Width="{Binding CellWidth}"/>
        <ColumnDefinition Width="{Binding CellWidth}"/>
        <ColumnDefinition Width="{Binding CellWidth}"/>
    </Grid.ColumnDefinitions>

    <!-- Header Row-->
    <ContentPresenter Grid.Row="0" Grid.Column="0">
        <ContentPresenter.ContentTemplate>
            <DataTemplate>
                <TextBlock Text="{Binding DaysOfWeek[0]}"/>
            </DataTemplate>
        </ContentPresenter.ContentTemplate>
    </ContentPresenter>
    <ContentPresenter ContentTemplate="{StaticResource CalendarHeaderCellTemplate}" Grid.Row="0" Grid.Column="1" DataContext="{Binding DaysOfWeek[1]}"/>
    <ContentPresenter ContentTemplate="{StaticResource CalendarHeaderCellTemplate}" Grid.Row="0" Grid.Column="2" DataContext="{Binding DaysOfWeek[2]}"/>
    <ContentPresenter ContentTemplate="{StaticResource CalendarHeaderCellTemplate}" Grid.Row="0" Grid.Column="3" DataContext="{Binding DaysOfWeek[3]}"/>
    <ContentPresenter ContentTemplate="{StaticResource CalendarHeaderCellTemplate}" Grid.Row="0" Grid.Column="4" DataContext="{Binding DaysOfWeek[4]}"/>
    <ContentPresenter ContentTemplate="{StaticResource CalendarHeaderCellTemplate}" Grid.Row="0" Grid.Column="5" DataContext="{Binding DaysOfWeek[5]}"/>
    <ContentPresenter ContentTemplate="{StaticResource CalendarHeaderCellTemplate}" Grid.Row="0" Grid.Column="6" DataContext="{Binding DaysOfWeek[6]}"/>

    <!-- 1st Row-->
    <ContentPresenter ContentTemplate="{StaticResource CalendarCellTemplate}" Grid.Row="1" Grid.Column="0"/>
    <ContentPresenter ContentTemplate="{StaticResource CalendarCellTemplate}" Grid.Row="1" Grid.Column="1"/>
    <ContentPresenter ContentTemplate="{StaticResource CalendarCellTemplate}" Grid.Row="1" Grid.Column="2"/>
    <ContentPresenter ContentTemplate="{StaticResource CalendarCellTemplate}" Grid.Row="1" Grid.Column="3"/>
    <ContentPresenter ContentTemplate="{StaticResource CalendarCellTemplate}" Grid.Row="1" Grid.Column="4"/>
    <ContentPresenter ContentTemplate="{StaticResource CalendarCellTemplate}" Grid.Row="1" Grid.Column="5"/>
    <ContentPresenter ContentTemplate="{StaticResource CalendarCellTemplate}" Grid.Row="1" Grid.Column="6"/>

On so on: You see the pattern I guess.

依此类推：你看到我猜的模式。

Here's the CalendarHeaderCellTemplate

这是 CalendarHeaderCellTemplate

<DataTemplate x:Key="CalendarHeaderCellTemplate">
    <StackPanel Margin="5" Background="Blue">
        <TextBlock Text="{Binding}"></TextBlock>
    </StackPanel>
</DataTemplate>

And here's the important parts of the ViewModel:

这是 ViewModel 的重要部分：

 public ObservableCollection<string> DaysOfWeek { get; private set; }
 public MonthViewModel()
    {  
        this.DaysOfWeek = new ObservableCollection<string> {DayOfWeek.Monday.ToString(), DayOfWeek.Tuesday.ToString(), DayOfWeek.Wednesday.ToString(), 
            DayOfWeek.Thursday.ToString(), DayOfWeek.Friday.ToString(), DayOfWeek.Saturday.ToString(), DayOfWeek.Sunday.ToString()};

    }

Now neither the Contentpresenter where I define the DataTemplate 'inline' does display anything inside its TextBlock nor the CalendarHeaderCellTemplate.

现在，我定义 DataTemplate 'inline' 的 Contentpresenter 不会在其 TextBlock 和 CalendarHeaderCellTemplate 中显示任何内容。

Funny thing is, inside the Visual Studio designer, everything show up correctly, except for the first cell (i.e. the one with the inline template)

有趣的是，在 Visual Studio 设计器中，除了第一个单元格（即带有内联模板的单元格）外，所有内容都正确显示

Does anyone have a suggestion.

有没有人有建议。

N.B. The 'inline' template was mostly done for testing purposes.

注意“内联”模板主要用于测试目的。

EDIT: Doing this (see below) instead of using the ContentPresenter works fine. Maybe I use the ContentPresenter in a wrong manner?

编辑：这样做（见下文）而不是使用 ContentPresenter 工作正常。也许我以错误的方式使用 ContentPresenter？

 <StackPanel Grid.Row="0" Grid.Column="0">
     <TextBlock Text="{Binding DaysOfWeek[0]}"/>
 </StackPanel>

The reason I want to use a ContentPresenter is because the DataTemplate for the content of every cell is going to be much more than just a textbox in the end.

我想使用 ContentPresenter 的原因是因为每个单元格内容的 DataTemplate 最终将不仅仅是一个文本框。

回答by biju

Try changing your ContentPresenter to

尝试将您的 ContentPresenter 更改为

    <ContentPresenter Content="{Binding DaysOfWeek[0]}" Grid.Row="0" Grid.Column="0">
        <ContentPresenter.ContentTemplate>
            <DataTemplate>
                <TextBlock Text="{Binding}"/>
            </DataTemplate>
        </ContentPresenter.ContentTemplate>
    </ContentPresenter>

or

或者

  <ContentPresenter Content="{Binding}" Grid.Row="0" Grid.Column="0">
        <ContentPresenter.ContentTemplate>
            <DataTemplate>
                <TextBlock Text="{Binding DaysOfWeek[0]}"/>
            </DataTemplate>
        </ContentPresenter.ContentTemplate>
    </ContentPresenter>

and also replace your DataContext with Content like

并将您的 DataContext 替换为 Content 之类的

<ContentPresenter ContentTemplate="{StaticResource CalendarHeaderCellTemplate}" Grid.Row="0" Grid.Column="1" Content="{Binding DaysOfWeek[1]}"/>

回答by Dean Chalk

try using ContentControl rather than ContentPresenter

尝试使用 ContentControl 而不是 ContentPresenter

<Style x:Key="CalendarCell" TargetType="ContentControl">
  <Setter Property="Template">
    <Setter.Value>
      <ControlTemplate TargetType="ContentControl">
        <StackPanel Margin="5" Background="{TemplateBinding Background}">
          <TextBlock Text="{TemplateBinding Content}" 
                     Foreground="{TemplateBinding Foreground}" />
        </StackPanel>
      </ControlTemplate>
    </Setter.Value>
  </Setter>
</Style>

<!-- Header Row-->
<ContentControl Style="{StaticResource CalendarCell}" 
                Content="{Binding DaysOfWeek[0]}" 
                Background="Blue" 
                Foreground="White" />
<ContentControl Style="{StaticResource CalendarCell}" 
                Content="{Binding DaysOfWeek[1]}" 
                Background="Blue" 
                Foreground="White" 
                Grid.Column="1" />
<ContentControl Style="{StaticResource CalendarCell}" 
                Content="{Binding DaysOfWeek[2]}" 
                Background="Blue" 
                Foreground="White" 
                Grid.Column="2"  />
<ContentControl Style="{StaticResource CalendarCell}" 
                Content="{Binding DaysOfWeek[3]}" 
                Background="Blue" 
                Foreground="White" 
                Grid.Column="3"  />
<ContentControl Style="{StaticResource CalendarCell}" 
                Content="{Binding DaysOfWeek[4]}" 
                Background="Blue" 
                Foreground="White" 
                Grid.Column="4"  />
<ContentControl Style="{StaticResource CalendarCell}" 
                Content="{Binding DaysOfWeek[5]}" 
                Background="Blue" 
                Foreground="White" 
                Grid.Column="5"  />
<ContentControl Style="{StaticResource CalendarCell}" 
                Content="{Binding DaysOfWeek[6]}" 
                Background="Blue" 
                Foreground="White" 
                Grid.Column="6"  />

<!-- 1st Row-->
<ContentControl Style="{StaticResource CalendarCell}" 
                Content="" 
                Background="Wheat" 
                Foreground="Black" 
                Grid.Row="1"  />
<ContentControl Style="{StaticResource CalendarCell}" 
                Content="" 
                Background="Wheat" 
                Foreground="Black" 
                Grid.Column="1" 
                Grid.Row="1"  />
<ContentControl Style="{StaticResource CalendarCell}" 
                Content="" 
                Background="Wheat" 
                Foreground="Black" 
                Grid.Column="2" 
                Grid.Row="1"  />
<ContentControl Style="{StaticResource CalendarCell}" 
                Content="" 
                Background="Wheat" 
                Foreground="Black" 
                Grid.Column="3" 
                Grid.Row="1"  />
<ContentControl Style="{StaticResource CalendarCell}" 
                Content="" 
                Background="Wheat" 
                Foreground="Black" 
                Grid.Column="4" 
                Grid.Row="1"  />
<ContentControl Style="{StaticResource CalendarCell}" 
                Content="" 
                Background="Wheat" 
                Foreground="Black" 
                Grid.Column="5" 
                Grid.Row="1"  />
<ContentControl Style="{StaticResource CalendarCell}" 
                Content="" 
                Background="Wheat" 
                Foreground="Black" 
                Grid.Column="6" 
                Grid.Row="1"  />