WPF，ValidationRule中的属性从未设置 [英] WPF, property in ValidationRule never set

问题描述

我正在尝试将 DataContext 中的属性绑定到 ValidationRule 中的属性：

I'm trying to bind a property in my DataContext to a property in a ValidationRule:

public class ReleaseValidationRule : ValidationRule
{
    // I want to bind a value from my DataContext to this property:
    public CheckboxViewModels ValidReleases { get; set; }
    ...
}

基于此线程，我创建了 CheckboxViewModels 类只是用作 List< CheckboxViewModel> 的包装，因此列表可以是 DependencyProperty ，以便我可以绑定到它。但是，在我的 ValidationRule 的 Validate 方法中， ValidReleases 列表始终为空。这是我的XAML：

Based on this thread, I created the CheckboxViewModels class just to act as a wrapper for a List<CheckboxViewModel> so that the list could be a DependencyProperty so that I could bind to it. However, in my Validate method on my ValidationRule, the ValidReleases list is always empty. Here's my XAML:

<TextBox>
    <TextBox.Text>
        <Binding Path="Release" UpdateSourceTrigger="PropertyChanged">
            <Binding.ValidationRules>
                <local:ReleaseValidationRule>
                    <local:ReleaseValidationRule.ValidReleases>
                        <local:CheckboxViewModels List="{Binding Path=Releases,
                            Converter={StaticResource debugConverter}}"/>
                    </local:ReleaseValidationRule.ValidReleases>
                </local:ReleaseValidationRule>
            </Binding.ValidationRules>
        </Binding>
    </TextBox.Text>
</TextBox>

我知道 Releases 属性（我知道'm绑定到 CheckboxViewModels 的 List 属性的内容具有内容，因为我有一个 TreeView 在 TextBox 上方，该文本框显示 Releases 的内容。我在 CheckboxViewModels.List 绑定中拥有的转换器没有任何作用，它只是我可以设置断点的地方。有趣的是，转换器断点永远不会被击中。好像整行< local：CheckboxViewModels List = {Binding Path = Releases，Converter = {StaticResource debugConverter}} /> 从未执行过，所以我的 ValidationRule 中的 ValidReleases 属性从未设置。

I know the Releases property (what I'm binding to the List property of CheckboxViewModels) has content because I have a TreeView just above the TextBox that shows the contents of Releases. The converter I have on the CheckboxViewModels.List binding does nothing, it's just a place where I can set a breakpoint. The funny thing is, that converter breakpoint never gets hit. It's as if the whole line <local:CheckboxViewModels List="{Binding Path=Releases, Converter={StaticResource debugConverter}}"/> never gets executed, so the ValidReleases property in my ValidationRule never gets set. What's going on?

编辑：这是 CheckboxViewModels 的样子：

public class CheckboxViewModels : DependencyObject, IList<CheckboxViewModel>,
    IEnumerable<CheckboxViewModel>
{
    ...members necessary to implement IList, IEnumerable...

    public static readonly DependencyProperty ListProperty =
        DependencyProperty.Register(
            "List",
            typeof(List<CheckboxViewModel>),
            typeof(CheckboxViewModels),
            new PropertyMetadata(new List<CheckboxViewModel>())
        );

    public List<CheckboxViewModel> List
    {
        get { return (List<CheckboxViewModel>)GetValue(ListProperty); }
        set { SetValue(ListProperty, value); }
    }
}

推荐答案

我停止使用验证规则，而是遵循关于实现 IDataErrorInfo 的教程。那是我进入 this [string] 找出错误消息时的类实例已完全初始化。我一直试图传递的数据只是来自同一实例上另一个属性的数据。也就是说，我想使用来自 Property2 的一些数据来验证 Property1 。使用 IDataErrorInfo ，当我验证 Property1 并在必要时组装错误消息时，我可以访问 Property2 ，而无需传入任何内容。

I stopped using validation rules and instead followed this tutorial about implementing IDataErrorInfo. That was my class instance is fully initialized by the time I get into this[string] to figure out the error message. The data I had been trying to pass in was just data from another property on the same instance. That is, I wanted to validate Property1 using some data from Property2. With IDataErrorInfo, when I'm validating Property1 and assembling an error message if necessary, I have access to Property2 as desired, without having to pass anything in.

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