依赖属性重置设置的DataContext

Question

后，我有一个用户控件（AgreementDetails）在WPF与下面的DependencyProperty和功能：

// 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; 
    } 

我用这个用户控件来显示在另一个用户控件（控制板）一个提示，我设置在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，我用的是AGREEMENTID来从数据库中获取一些数据在用户控件来显示。我这样做的第一次，一切顺利。但是，当我在AgreementDetails中将传入的WCF DataContract设置为datacontext时，AgreementID属性重置为0，因此第二次调用将不起作用，因为显然我没有与AgreementID = 0达成一致。我检查并将AgreementID重置为SetBindingContext （）;方法设置DataContext之后。

我如何使它在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：我现在有下面的代码：

// 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; 
    } 

我仍然有该DataContext设置后AGREEMENTID重置为0的问题。

此外，当我用下面的语句来绑定，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，以便绑定不重置我DependencyProperty和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" /> 

Elem entName = AgreementDetails是我的UserControl的名称。奇怪的是{RelativeSource Self}它不起作用...

Answer 1

当你在你的UserControl中设置datacontext时，你实际上也在重置父控件中的数据上下文（Dashboard）。这是相同的背景。因此，您的协议ID不再处于上下文中，因此得到重置。

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，但会影响该控件中声明的AgreementId绑定使用的数据上下文。绑定在Dashboard控件中声明，但绑定实际上是在您要重置的子控件的数据上下文中查找的。

见我类似的问题在这里： Setting DataContext within UserControl is affecting bindings in parent

编辑：这里是我的意思是：

// 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; 
} 

然后在你的AgreementDetails。XAML，你可能有这样的：

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

结合需要改变到其中：

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