如何在TextBox.Triggers（事件触发器）上执行某些操作？

I have to disable a some button.

我必须禁用一些按钮。

How I can use TextBox.Triggers for that?

我怎么能用TextBox.Triggers呢？

Are there any samples?

有样品吗？

Thank you for reply!

感谢您的回复！

3 个解决方案

#1

Let's say you have a TextBox and a Button, and you want to disable your Button when TextBox is empty. This can be easily achieved with DataTriggers:

假设你有一个TextBox和一个Button，你想在TextBox为空时禁用你的Button。使用DataTriggers可以轻松实现这一点：

<TextBox x:Name="textBox" />
<Button>
    <Button.Style>
        <Style>
            <Style.Triggers>
                <DataTrigger Binding="{Binding Text, ElementName=textBox}" Value="">
                    <Setter Property="Button.IsEnabled" Value="False" />
                </DataTrigger>
            </Style.Triggers>
        </Style>
    </Button.Style>
</Button>

#2

I am assuming this is related to your other question about triggering the Enabled property on a Button based on if a TextBox has a validation error or not.

我假设这与你在Button上触发Enabled属性的其他问题相关，基于TextBox是否有验证错误。

If that's so, you would use a DataTrigger to test the TextBox.Validation.HasError property to see if it has any errors, and if so disable the Button

如果是这样，您将使用DataTrigger测试TextBox.Validation.HasError属性以查看它是否有任何错误，如果是，则禁用Button

<Style x:Key="MyButtonStyle" TargetType="{x:Type Button}">
    <Setter Property="IsEnabled" Value="True" />
    <DataTrigger Binding="{Binding ElementName=MyTextBox, Path=Validation.HasError" Value="True">
        <Setter Property="IsEnabled" Value="False"/>
    </DataTrigger>
</Style>

Be sure you bind your TextBox with ValidatesOnDataErrors="True" for this to work

确保将TextBox与ValidatesOnDataErrors =“True”绑定，以使其正常工作

<TextBox x:Name="MyTextBox" Text="{Binding SomeText, ValidatesOnDataErrors=True }" />

As a side note, my comment on your other question still applies here. I would personally implement IDataErrorInfo in your ViewModel and make the SaveCommand.CanExecute() only return true if ViewModel.IsValid. Then it will automatically take care of disabling the button if the SaveCommand is not supposed to execute

作为旁注，我对您的其他问题的评论仍然适用于此。我个人会在ViewModel中实现IDataErrorInfo，并使SaveCommand.CanExecute（）仅在ViewModel.IsValid时返回true。然后，如果不应该执行SaveCommand，它将自动关闭禁用按钮

#3

Although posting code sample would be helpful and would allow a much better solution, I can still recommend data binding. Something like

虽然发布代码示例会有所帮助并且可以提供更好的解决方案，但我仍然可以推荐数据绑定。就像是

<Button Name="btnFoo"
        Enabled="{Binding ElementName=txtblkBar, Converter={StaticResource ButtonVisibilityConverter}"/>

where the resources section of your control contains

控件的resources部分包含的位置

<local:ButtonVisibilityConverter Name="ButtonVisibilityConverter"/>

and you have defined a class ButtonVisibilityConverter in the namespace referenced by local. The Data Conversion section of the page I linked to above has an example converter class.

并且您已在local引用的命名空间中定义了一个ButtonVisibilityConverter类。我上面链接的页面的数据转换部分有一个示例转换器类。

EDIT:

编辑：

Code that sets the button to disabled whenever txtblkBar is empty:

每当txtblkBar为空时将按钮设置为禁用的代码：

[ValueConversion(typeof(TextBlock), typeof(bool?))]
public class ButtonVisibilityConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        TextBlock txtblk = value as TextBlock;
        if (null == txtblk)
            return false;
        return !string.IsNullOrEmpty(txtblk.Text);
    }

    public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        // Don't need to use the back conversion
        throw new NotImplementedException();
    }
}

#1