[英]WPF: Binding Property from User Control to ViewModel
我有一个名为AntecedentControl的UserControl:
XAML:
<UserControl x:Name="AntecedentUserControl">
<ScrollViewer DataContext="{Binding ElementName=AntecedentUserControl}">
<telerik:RadGridView ItemsSource="{Binding Path=AntecedentList}"
AutoGenerateColumns="False"
<telerik:RadGridView.Columns>
<telerik:GridViewDataColumn DataMemberBinding="{Binding Section, Mode=TwoWay}"
Header="Seccion"
IsVisible="True"
IsFilterable="False"/>
<telerik:GridViewDataColumn DataMemberBinding="{Binding Group, Mode=TwoWay}"
Header="Grupo"
IsVisible="True"
IsFilterable="False"/>
<telerik:GridViewDataColumn DataMemberBinding="{Binding Tome, Mode=TwoWay}"
Header="Tomo"
IsVisible="True"
IsFilterable="False"/>
<telerik:GridViewDataColumn DataMemberBinding="{Binding Volume, Mode=TwoWay}"
Header="Volumen"
IsVisible="True"
IsFilterable="False"/>
<telerik:GridViewDataColumn DataMemberBinding="{Binding Inscription, Mode=TwoWay}"
Header="Inscripcion"
IsVisible="True"
IsFilterable="False"/>
<telerik:GridViewDataColumn DataMemberBinding="{Binding Bis, Mode=TwoWay}"
Header="Bis"
IsVisible="True"
IsFilterable="False"/>
<telerik:GridViewColumn>
<telerik:GridViewColumn.CellTemplate>
<DataTemplate>
<telerik:RadButton Content="Delete"
Command="telerikGrid:RadGridViewCommands.Delete"
CommandParameter="{Binding}"/>
</DataTemplate>
</telerik:GridViewColumn.CellTemplate>
</telerik:GridViewColumn>
</telerik:RadGridView.Columns>
</telerik:RadGridView>
</ScrollViewer>
后台代码(C#):
public partial class AntecedentControl : UserControl
{
public ObservableCollection<Antecedent> AntecedentList
{
get { return (ObservableCollection<Antecedent>)GetValue(AntecedentListProperty); }
set { SetValue(AntecedentListProperty, value); }
}
public static readonly DependencyProperty AntecedentListProperty =
DependencyProperty.Register("AntecedentList",
typeof(ObservableCollection<Antecedent>),
typeof(AntecedentControl),
new FrameworkPropertyMetadata(new ObservableCollection<Antecedent>(), OnListPropertyChanged));
private static void OnListPropertyChanged(DependencyObject source, DependencyPropertyChangedEventArgs e)
{
var antecedentList = source as AntecedentControl;
var value = e.NewValue as ObservableCollection<Antecedent>;
antecedentList.AntecedentList = value;
}
public AntecedentControl()
{
InitializeComponent();
}
}
而且,在另一个视图上,我这样调用UserControl:
<DomainTransmissionControls:AntecedentControl AntecedentList="{Binding ElementName=AntecedentUserControl, Path=Antecedents, Mode=TwoWay}"/>
在此单独视图的ViewModel上,我有一个名为“ Antecedents”的属性:
public ObservableCollection<Antecedent> Antecedents { get; set; }
简而言之:AntecedentControl UC是一个网格,具有一种您可以在其中添加/编辑项目的方法。 当前UC的属性“ AntecedentList”是列表的“保存”位置。
调用“ AntecedentControl”的另一个UC的ViewModel的“ Antecedents”属性应绑定到AntecedentControl UC的“ AntecedentList”。
我想知道如何将ViewModel上的此属性绑定到在单独的UserControl(AntecedentControl)中找到的“ AntecedentList”属性,因为此当前代码返回null。
我相信AntecedentControl UC上的DependencyProperty声明有问题,因为在'OnListPropertyChanged'方法上放置一个断点表明e.NewValue返回null。
如果是这样,为什么不返回在Dependency Property语句中声明的默认值?
感谢您的时间。
您的绑定似乎不正确。 您似乎正在尝试访问已创建的UserControl中的元素(AntecedentUserControl)?
除非为简单起见而遗漏了一些代码,否则实际上似乎根本不需要DependencyProperty? 有什么原因不能设置DataContext?
SomeView.xaml
<DomainTransmissionControls:AntecedentControl DataContext="{Binding Antecedents}" />
SomeViewModel.cs
private ObservableCollection<Antecedent> _antecedents;
public ObservableCollection<Antecedent> Antecedents
{
get
{
if (_antecedents == null)
_antecedents = new ObservableCollection<Antecedent>();
return _antecedents;
}
}
AntecedentControl.xaml
<UserControl>
<ScrollViewer>
<telerik:RadGridView ItemsSource="{Binding}" AutoGenerateColumns="False">
<telerik:RadGridView.Columns>
<telerik:GridViewDataColumn DataMemberBinding="{Binding Section, Mode=TwoWay}"
Header="Seccion" IsFilterable="False" IsVisible="True" />
<!-- Additional column definitions. -->
</telerik:RadGridView.Columns>
</telerik:RadGridView>
</ScrollViewer>
</UserControl>
AntecedentControl.xaml.cs
public partial class AntecedentControl : UserControl
{
public AntecedentControl()
{
InitializeComponent();
}
}
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