參數為hibernateConnector的DataGridTextColumn ValidationRule不起作用

Question

我嘗試為DataGridTextColumn實施ValidationRule，該方法應針對NHibernate屬性測試可空性。 該檢查實際上是在我的HibernateConnector.isNullable(String className, String propertyName)方法中完成的。 因此，必須將HibernateConnector傳遞給ValidationRule。

下面引用的mynamespace.TeamsForm.xaml.cs具有public HibernateConnector hibernateConnector { get; set; } public HibernateConnector hibernateConnector { get; set; }

由於我是WPF / XAML的新手，因此我使用https://social.technet.microsoft.com/wiki/contents/articles/31422.wpf-passing-a-data-bound-value-to-a-實現了它以validation-rule.aspx為例。

包裝類

public class HibernateConnectionWrapper : DependencyObject
{
    public static readonly DependencyProperty HibernateConnectorProperty =
         DependencyProperty.Register("hibernateConnector", typeof(HibernateConnector),
         typeof(HibernateConnectionWrapper), new FrameworkPropertyMetadata(null));

    public HibernateConnector hibernateConnector
    {
        get { return (HibernateConnector)GetValue(HibernateConnectorProperty); }
        set { SetValue(HibernateConnectorProperty, value); }
    }
}

綁定代理

public class BindingProxy : Freezable
{
    protected override Freezable CreateInstanceCore()
    {
        return new BindingProxy();
    }

    public object Data
    {
        get { return (object)GetValue(DataProperty); }
        set { SetValue(DataProperty, value); }
    }

    public static readonly DependencyProperty DataProperty =
        DependencyProperty.Register("Data", typeof(object), typeof(BindingProxy), new PropertyMetadata(null));
}

驗證類

public class EditRueckennummerValidationRule : ValidationRule
{
    public HibernateConnectionWrapper Wrapper { get; set; }

    public override ValidationResult Validate(object value, System.Globalization.CultureInfo cultureInfo)
    {
        bool n = Wrapper.hibernateConnector.isNullable(typeof(SpielerImTeam).FullName, "Rueckennummer");
        // ... more code

相關的XAML部分

<rcappbase:AbstractWorkAreaForm x:Class="mynamespace.TeamsForm"
  ...  
<DataGrid.Resources>
    <BindingProxy Data="{Binding}" x:Key="proxy"/>
</DataGrid.Resources>
<!-- other elements -->
<DataGridTextColumn Header="rueckennummer" IsReadOnly="False" DisplayIndex="5" >
    <DataGridTextColumn.Binding>
        <Binding Path="Rueckennummer" NotifyOnValidationError="True">
            <Binding.ValidationRules>
                <local:EditRueckennummerValidationRule>
                    <local:EditRueckennummerValidationRule.Wrapper>
                        <mynamespaceandassembly:HibernateConnectionWrapper  hibernateConnector="{Binding Path=Data.hibernateConnector, Source={StaticResource proxy}}"/>
                    </local:EditRueckennummerValidationRule.Wrapper>
                </local:EditRueckennummerValidationRule>
            </Binding.ValidationRules>  
        </Binding>
    </DataGridTextColumn.Binding>
</DataGridTextColumn>
<!-- more elements -->

我可以編譯和運行代碼，但在EditRueckennummerValidationRule.Validate(...)在Wrapper.hibernateConnector.isNullable(...) hibernateConnector為空 。

那我在做什么錯呢？ 與BindingProxy有關（我看到的所有示例顯然都具有相同的代碼）嗎？

Answer 1

我需要一段時間來理解“數據上下文”，但同時我想解決了自己的問題：

我搬家了

<DataGrid.Resources>
    <BindingProxy Data="{Binding}" x:Key="proxy"/>
</DataGrid.Resources>

至

<rcappbase:AbstractWorkAreaForm.Resources>
    <BindingProxy Data="{Binding }" x:Key="proxy"/>
</rcappbase:AbstractWorkAreaForm.Resources>

並添加了一行

public TeamsForm()
{
    InitializeComponent();
    DataContext = this; // <-- !!!! set the data context
}

我從上面引用的示例中錯過了這一行！ 現在，在驗證時已設置Wrapper.hibernateConnector 。