Question

我在WPF中有一个带有以下DependencyProperty和函数的UserControl（AgreementDetails）：

// UserControl AgreementDetails
    public int AgreementID
        {
            get { return Convert.ToInt32(GetValue(AgreementIDProperty)); }
            set { SetValue(AgreementIDProperty, value); }

        }

    public static readonly DependencyProperty AgreementIDProperty = DependencyProperty.Register("AgreementID", typeof(int), typeof(UC1001_AgreementDetails_View), new PropertyMetadata(null));

    private void UserControl_Loaded(object sender, RoutedEventArgs e)
    {
        int id = AgreementID;

        if (id > 0)
        {
            GetData();
            SetBindingContext();
            this.Visibility = System.Windows.Visibility.Visible;
        }
        else
        {
            this.Visibility = System.Windows.Visibility.Collapsed;
        }
    }

    private void GetData()
    {
        ConsultantServiceClient client = new ConsultantServiceClient();
        _contract = new UC1001_ActiveAgreementContract();
        _contract = client.GetAgreementDetailsByAgreementID(AgreementID);
    }

    private void SetBindingContext()
    {
        this.DataContext = _contract;
    }

我使用此UserControl在另一个UserControl（仪表板）中显示为工具提示，我在其中设置了AgreementID属性：

// Dashboard    
<Setter Property="DataGridCell.ToolTip">
      <Setter.Value>
             <my:UC1001_AgreementDetails_View Background="#FFF" Opacity="0.88" AgreementID="{Binding Months[9].AgreementID}"/>
      </Setter.Value>
</Setter>

在AgreementDetails中，我使用AgreementID从数据库中获取一些数据以显示在UserControl中。我第一次这样做，一切顺利。但是当我将传入的WCF DataContract设置为AgreementDetails中的datacontext时，AgreementID属性重置为0，因此第二次调用将不起作用，因为很明显我没有与AgreementID = 0的协议。我检查了协议ID并重置了SetBindingContext （）;设置DataContext后的方法。

如何在AgreementDetails中设置新的dataContext后，不会重置AgreementID属性？

如果需要，可以提供更多信息。

编辑：我现在有以下代码：

// Dependency properties
 public int AgreementID
 {
    get { return (int)GetValue(AgreementIDProperty); }
    set { SetValue(AgreementIDProperty, value); }
 }

 public UC1001_ActiveAgreementContract AgreementDetailsContract
 {
    get { return (UC1001_ActiveAgreementContract)GetValue(AgreementDetailsContractProperty); }
    set { SetValue(AgreementDetailsContractProperty, value); }

 }

    public static readonly DependencyProperty AgreementIDProperty = DependencyProperty.Register("AgreementID", typeof(int), typeof(UC1001_AgreementDetails_View), new PropertyMetadata(null));
    public static readonly DependencyProperty AgreementDetailsContractProperty = DependencyProperty.Register("AgreementDetailsContract", typeof(UC1001_ActiveAgreementContract), typeof(UC1001_AgreementDetails_View), new PropertyMetadata(null));

    private void UserControl_Loaded(object sender, RoutedEventArgs e)
    {
        int id = AgreementID;

        if (id > 0)
        {
            GetData();
            SetBindingContext();
            this.Visibility = System.Windows.Visibility.Visible;
        }
        else
        {
            this.Visibility = System.Windows.Visibility.Collapsed;
        }
    }

    private void GetData()
    {
        ConsultantServiceClient client = new ConsultantServiceClient();
        AgreementDetailsContract = client.GetAgreementDetailsByAgreementID(AgreementID);
    }

    private void SetBindingContext()
    {
       this.DataContext = AgreementDetailsContract;
    }

我仍然遇到在设置DataContext后，AgreementID重置为0的问题。

当我使用以下语句进行绑定时，我得到一个空标签：

<Label Content="{Binding RelativeSource={RelativeSource Self}, Path=AgreementDetailsContract.EndClientName}" />

解决：

我删除了SetDataBinding（）方法，因此Binding不会重置我的DependencyProperty，而对于我的标签的绑定，我使用了以下Binding（而不是RelativeSource Self）：

 <Label Content="{Binding ElementName=AgreementDetails, Path=AgreementDetailsContract.EndClientName}" Grid.Column="1" Grid.Row="1" Height="28" HorizontalAlignment="Left" Margin="11,0,0,0" Name="_labelEindklant" VerticalAlignment="Top" />

ElementName = AgreementDetails是我的UserControl的名称。 {RelativeSource Self}很奇怪它没有用......

Answer 1

在Usercontrol中设置datacontext时，实际上也是在父控件中重置数据上下文（仪表板）。这是相同的背景。因此，您的协议ID不再在上下文中，因此会重置。

编辑：其实我没说得那么好。您不会影响仪表板中的数据上下文，但是您正在影响在该控件中声明的AgreementId绑定所使用的数据上下文。绑定在Dashboard控件中声明，但绑定实际上是在您正在重置的子控件的数据上下文中查找。

在这里查看我的类似问题： Setting DataContext within UserControl is affecting bindings in parent

编辑：这就是我的意思：

// UserControl AgreementDetails
public int AgreementID
{
    get { return Convert.ToInt32(GetValue(AgreementIDProperty)); }
    set { SetValue(AgreementIDProperty, value); }
}

//The new property to bind to instead of DataContext
public UC1001_ActiveAgreementContract Agreement
{
    get { return (UC1001_ActiveAgreementContract)GetValue(AgreementProperty); }
    private set { SetValue(AgreementProperty, value); }
}

public static readonly DependencyProperty AgreementIDProperty = DependencyProperty.Register("AgreementID", typeof(int), typeof(UC1001_AgreementDetails_View), new PropertyMetadata(null));

//should really be readonly dependency property
public static readonly DependencyProperty AgreementProperty = DependencyProperty.Register("Agreement", typeof(UC1001_ActiveAgreementContract), typeof(UC1001_AgreementDetails_View), new PropertyMetadata(null));**

private void UserControl_Loaded(object sender, RoutedEventArgs e)
{
    int id = AgreementID;

    if (id > 0)
    {
        GetData();
        SetBindingContext();
        this.Visibility = System.Windows.Visibility.Visible;
    }
    else
    {
        this.Visibility = System.Windows.Visibility.Collapsed;
    }
}

private void GetData()
{
    ConsultantServiceClient client = new ConsultantServiceClient();
    _contract = new UC1001_ActiveAgreementContract();
    _contract = client.GetAgreementDetailsByAgreementID(AgreementID);
}

private void SetBindingContext()
{
    this.Agreement = _contract;
}

然后在您的AgreementDetails.xaml中，您可能会有类似的内容：

<!-- Bound to property in DataContext -->
<TextBlock Text={Binding SomeContractProperty} />

哪个绑定需要更改为：

<!-- Bound to new property on UC1001_AgreementDetails_View (UserControl) -->
<TextBlock Text={Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type UC1001_AgreementDetails_View}}, Path=Agreement.SomeContractProperty} />

设置DataContext后重置属性重置

1 个答案: