DataTrigger使WPF按钮处于非活动状态，直到文本框具有价值

问题描述：

我要的按钮控件的属性是的IsEnabled =FALSE直至值输入到一个文本框在窗口。

I want the Button control's property to be IsEnabled="False" until a value is entered into a TextBox in the Window.

code到目前为止：

<Button
  Content="Click Me"
  Name="ClickMe"
  VerticalAlignment="Top"
  Click="ClickMe_Click">
  <Button.Style>
    <Style>
      <Style.Triggers>
        <DataTrigger
          Binding="{Binding ElementName=textBox, Path=Length}"
          <!-- or even: Binding="{Binding Path=textBox.Length}" -->
          Value="0">
          <Setter
            Property="Button.IsEnabled"
            Value="false" />
          </DataTrigger>
      </Style.Triggers>
    </Style>
  </Button.Style>
</Button>

此外，是有可能有这种按钮控件的的IsEnabled 属性是基于3种不同的文本框控制所有具有价值？

Also, is it possible to have this Button control's IsEnabled property be based on 3 different TextBox controls all having values?

答

假设你正在采用presentation模式，比如一个视图模型，你应该直接绑定的UI元素的数据，而不是。

Assuming you are employing a presentation model, such as a ViewModel, you should bind directly the data instead of the UI elements.

<Style.Triggers>
    <MultiDataTrigger>
        <MultiDataTrigger.Conditions>
            <Condition Binding="{Binding FirstName}" Value="{x:Null}" />
            <Condition Binding="{Binding MiddleName}" Value="{x:Null}" />
            <Condition Binding="{Binding LastName}" Value="{x:Null}" />
        </MultiDataTrigger.Conditions>
        <Setter Property="Button.IsEnabled" Value="False" />
    </MultiDataTrigger>
</Style.Triggers>

这是说，如果你使用的是presentation模式，你可以随时添加一个布尔EnableSave财产和处理所有的presentation逻辑有而不是在视图本身。

That said, if you are using a presentation model, you can always add a bool "EnableSave" property and handle all the presentation logic there instead of in the view itself.

由于可以通过下面的评论中可以看出，我错误地设置这使按钮时的任意的文本框具有价值，但要求是按钮启用时的所有的文本框 ES具有价值。

As can be seen by following the comments, I mistakenly set this up to enable the Button when any TextBox has a value, but the requirement is that the Button be enabled when all TextBoxes have values.

从概念上讲，所有你需要做的是反向的条件 - 而不是假，如果所有条件假的，我们想要的。如此，如果所有条件属实

Conceptually, all you have to do is reverse the conditions -- instead of "false if all conditions false," we want "true if all conditions true."

美中不足的是，有没有办法在XAML说不空 - 没办法不使用的IValueConverter ，那是。我想创建一个 NullToBoolConverter 的回报假为空和真为！= NULL 。

The catch is that there is no way to say "not null" in the XAML -- no way without an IValueConverter, that is. I'd create a NullToBoolConverter that returns false for null and true for != null.

由于这种转换器：

<Style.Triggers>
    <MultiDataTrigger>
        <MultiDataTrigger.Conditions>
            <Condition Binding="{Binding FirstName,
                Converter={StaticResource NullToBoolConverter}}" Value="True" />
            <Condition Binding="{Binding MiddleName,
                Converter={StaticResource NullToBoolConverter}}" Value="True" />
            <Condition Binding="{Binding LastName,
                Converter={StaticResource NullToBoolConverter}}" Value="True" />
        </MultiDataTrigger.Conditions>
        <Setter Property="Button.IsEnabled" Value="True" />
    </MultiDataTrigger>
</Style.Triggers>

DataTrigger使WPF按钮处于非活动状态，直到文本框具有价值

相关推荐