如何清除MVVM中的文本框? [英] How to clear a TextBox in MVVM?
问题描述
我在DataTemplate中有一个文本框,声明如下:
<TextBox Grid.Row="1" Grid.Column="1" Margin="0,4,0,0">
<i:Interaction.Triggers>
<i:EventTrigger EventName="LostFocus">
<cmd:EventToCommand Command="{Binding DataContext.NotesEnteredCommand,
RelativeSource={RelativeSource FindAncestor, AncestorType=Window}}">
<cmd:EventToCommand.CommandParameter>
<MultiBinding Converter="{StaticResource SimpleMultiValueConverter}">
<Binding Path="Row.OID" />
<Binding Path="Text" RelativeSource="{RelativeSource FindAncestor, AncestorType=TextBox}" />
</MultiBinding>
</cmd:EventToCommand.CommandParameter>
</cmd:EventToCommand>
</i:EventTrigger>
</i:Interaction.Triggers>
<TextBox.InputBindings>
<KeyBinding Key="Enter" Command="{Binding DataContext.NotesEnteredCommand, RelativeSource={RelativeSource FindAncestor, AncestorType=Window}}">
<KeyBinding.CommandParameter>
<MultiBinding Converter="{StaticResource SimpleMultiValueConverter}">
<Binding Path="Row.OID" />
<Binding Path="Text" RelativeSource="{RelativeSource FindAncestor, AncestorType=TextBox}" />
</MultiBinding>
</KeyBinding.CommandParameter>
</KeyBinding>
</TextBox.InputBindings>
此TextBox的基本功能是在按下Enter键或失去焦点时执行MVVM-Light RelayCommand.
我的问题是,在上述两种情况下,我无法在MVVM中找到一种通过XAML清除TextBox的 Text 值的方法.使用代码隐藏非常容易,但是我无法在MVVM中弄清楚.
有什么想法吗?
如果文本是数据层和应用程序逻辑的一部分,则Model
或ViewModel
中应存在一个字符串,并从该字符串中清除 >
例如,
<TextBox Text="{Binding NewNote}" ... />
和
void NotesEntered(int oid)
{
SaveNewNote(oid);
NewNote = string.Empty;
}
如果仅是UI层的一部分,则应使用代码隐藏功能将其清除.在UI背后的代码中包含特定于UI的逻辑是完全可以接受的,因为这仍然可以保持层的分离.
NewNoteTextBox_LostFocus(object sender, EventArgs e)
{
(sender as TextBox).Text = string.Empty;
}
NewNoteTextBox_KeyDown(object sender, KeyEventArgs e)
{
if (e.Key == Keys.Enter)
(sender as TextBox).Text = string.Empty;
}
I have a TextBox in a DataTemplate declared as follows:
<TextBox Grid.Row="1" Grid.Column="1" Margin="0,4,0,0">
<i:Interaction.Triggers>
<i:EventTrigger EventName="LostFocus">
<cmd:EventToCommand Command="{Binding DataContext.NotesEnteredCommand,
RelativeSource={RelativeSource FindAncestor, AncestorType=Window}}">
<cmd:EventToCommand.CommandParameter>
<MultiBinding Converter="{StaticResource SimpleMultiValueConverter}">
<Binding Path="Row.OID" />
<Binding Path="Text" RelativeSource="{RelativeSource FindAncestor, AncestorType=TextBox}" />
</MultiBinding>
</cmd:EventToCommand.CommandParameter>
</cmd:EventToCommand>
</i:EventTrigger>
</i:Interaction.Triggers>
<TextBox.InputBindings>
<KeyBinding Key="Enter" Command="{Binding DataContext.NotesEnteredCommand, RelativeSource={RelativeSource FindAncestor, AncestorType=Window}}">
<KeyBinding.CommandParameter>
<MultiBinding Converter="{StaticResource SimpleMultiValueConverter}">
<Binding Path="Row.OID" />
<Binding Path="Text" RelativeSource="{RelativeSource FindAncestor, AncestorType=TextBox}" />
</MultiBinding>
</KeyBinding.CommandParameter>
</KeyBinding>
</TextBox.InputBindings>
What this TextBox basically does is execute a MVVM-Light RelayCommand when the Enter key is pressed or when losing focus.
My problem is that I cannot figure out a way in MVVM to clear the TextBox's Text value through XAML in the above two scenarios. It's very easy with in code-behind, but I can't figure it out in MVVM.
Any ideas?
If the text is part of your data layer and application logic, a string should exist in your Model
or ViewModel
and be cleared from there
For example,
<TextBox Text="{Binding NewNote}" ... />
and
void NotesEntered(int oid)
{
SaveNewNote(oid);
NewNote = string.Empty;
}
If it's part of the UI layer only, it should just be cleared with code-behind. It's perfectly acceptable to have UI-specific logic in the code-behind the UI, as that still maintains the separation of layers.
NewNoteTextBox_LostFocus(object sender, EventArgs e)
{
(sender as TextBox).Text = string.Empty;
}
NewNoteTextBox_KeyDown(object sender, KeyEventArgs e)
{
if (e.Key == Keys.Enter)
(sender as TextBox).Text = string.Empty;
}
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