MVVM Light 工具包 Interaction.Triggers 在数据模板中不触发
我可以使用 Interaction.Triggers 捕获文本框上的 textchanged 事件，如下所示：
<TextBox Text="{Binding Title}" Style="{StaticResource GridEditStyle}">
<i:Interaction.Triggers>
<i:EventTrigger EventName="TextChanged">
<cmd:EventToCommand Command="{Binding TextChanged}" />
</i:EventTrigger>
</i:Interaction.Triggers>
</TextBox>
但是，当我在列表视图单元模板的数据模板中使用它时，如下所示：
<ListView ItemsSource="{Binding LangaugeCollection}" SelectedItem="{Binding SelectedLangauge}" BorderThickness="0" FontFamily="Calibri" FontSize="11">
<ListView.View>
<GridView>
<GridViewColumn Width="200">
<GridViewColumn.CellTemplate>
<DataTemplate >
<Grid>
<TextBlock Text="{Binding Title}" Style="{StaticResource GridBlockStyle}">
</TextBlock>
<TextBox Text="{Binding Title}" Style="{StaticResource GridEditStyle}">
<i:Interaction.Triggers>
<i:EventTrigger EventName="TextChanged">
<cmd:EventToCommand Command="{Binding TextChanged}" />
</i:EventTrigger>
</i:Interaction.Triggers>
</TextBox>
</Grid>
</DataTemplate>
</GridViewColumn.CellTemplate>
</GridViewColumn>
</GridView>
</ListView.View>
</ListView>
该事件不会触发。
有谁知道为什么这不会触发以及如何修复它？
I can use Interaction.Triggers to catch the textchanged event on a textbox like so:
<TextBox Text="{Binding Title}" Style="{StaticResource GridEditStyle}">
<i:Interaction.Triggers>
<i:EventTrigger EventName="TextChanged">
<cmd:EventToCommand Command="{Binding TextChanged}" />
</i:EventTrigger>
</i:Interaction.Triggers>
</TextBox>
However when I use it in a datatemplate for a listview celltemplate as follows:
<ListView ItemsSource="{Binding LangaugeCollection}" SelectedItem="{Binding SelectedLangauge}" BorderThickness="0" FontFamily="Calibri" FontSize="11">
<ListView.View>
<GridView>
<GridViewColumn Width="200">
<GridViewColumn.CellTemplate>
<DataTemplate >
<Grid>
<TextBlock Text="{Binding Title}" Style="{StaticResource GridBlockStyle}">
</TextBlock>
<TextBox Text="{Binding Title}" Style="{StaticResource GridEditStyle}">
<i:Interaction.Triggers>
<i:EventTrigger EventName="TextChanged">
<cmd:EventToCommand Command="{Binding TextChanged}" />
</i:EventTrigger>
</i:Interaction.Triggers>
</TextBox>
</Grid>
</DataTemplate>
</GridViewColumn.CellTemplate>
</GridViewColumn>
</GridView>
</ListView.View>
</ListView>
the event will not trigger.
Does anyone know why this does not trigger and how to fix it?
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当您位于 DataTemplate 中时，DataContext 可能不是您所期望的。通常，DataTemplate 中的 DataContext 设置为 DataTemplate 表示的项目。如果您的 TextChanged 命令位于“主视图模型”而不是数据项上，则您需要更精确地指定数据绑定，例如：
Command="{Binding Source={StaticResource Locator}, Path= Main.TextChanged}”
当您在 Studio 中以调试模式 (F5) 运行代码并观察“输出”窗口时，您可以看到问题。如果 DataContext 设置不正确，将显示数据错误。
干杯，
洛朗
When you are in a DataTemplate, the DataContext might not be what you expect. Typically the DataContext in a DataTemplate is set to the item that the DataTemplate represents. If your TextChanged command is on the "main viewmodel" instead of the data item, you need to be more precise in the way that you specify the data binding, for example:
Command="{Binding Source={StaticResource Locator}, Path=Main.TextChanged}"
You can see the issue when you run the code in debug mode (F5) in Studio and observe the Output window. A Data Error will be shown if the DataContext is incorrectly set.
Cheers,
Laurent
似乎有东西在文本框之前处理事件。也许您可以监听 ViewModel 内部更改的 Title 属性（集合），因为无论如何您都在触发器内部的 ViewModel 上调用 TextChanged，我想。
顺便说一句，我认为您的绑定表达式中缺少 TwoWay 模式。
希望这有帮助。
It seems something handles the event before the TextBox. Maybe you could listen to Title property (collection) changed inside you ViewModel, because anyway you are calling TextChanged on ViewModel inside the trigger, I suppose.
Btw I think you're missing TwoWay mode in your binding expression.
Hope this helps.