WPF用户控件数据绑定不起作用 [英] WPF User Control Data Binding Not Working
问题描述
我正在创建一个简单的用户控件，将弹出窗口与文本视图结合在一起，这没什么疯狂的。首先，我将其设置在窗口中以对其进行样式设置时，它可以正常工作，但是当我将其移至用户控件中以完成它时，它将无法正常工作。
I'm creating a simple User Control combining a popup with a text view, nothing crazy. When I set it up in a window at first to style it all out, it worked perfectly, but when I moved it into a User Control to actually finish it up, it won't work correctly any more.
我将一个最小值和最大值传递给控件，然后它自动创建一个数字列表，供您在该范围内选择。在用户控件中，数字列表未正确绑定，谁知道原因。也许有人可以看看我的代码。
I pass a min and max value into the control and then it automatically creates a list of numbers to pick from in that range. In the User Control, the list of numbers doesn't get bound correctly, who knows why. Maybe someone can take a look at my code.
我还读过很多其他问题，但我真的不知道发生了什么。我的输出窗口没有任何错误，因此那里没有任何线索。无论如何，这是代码-
I've read a bunch of other questions about this, but don't really know what's happening. I'm not getting any errors in my output window, so no clues there. Anyway, here's the code -
UserControl.xaml
UserControl.xaml
<UserControl x:Class="UserControl1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
x:Name="Me"
DataContext="{Binding RelativeSource={RelativeSource Self}}">
<StackPanel>
<TextBox Name="myTextbox"
Height="30"
Margin="0"
FontSize="14"
IsReadOnly="True"
Padding="5,2"
Text="{Binding Value}" />
<Popup x:Name="myPopup"
PlacementTarget="{Binding ElementName=myTextbox}"
StaysOpen="True">
<Popup.Style>
<Style TargetType="{x:Type Popup}">
<Style.Triggers>
<DataTrigger Binding="{Binding ElementName=myTextbox, Path=IsFocused}" Value="True">
<Setter Property="IsOpen" Value="True" />
</DataTrigger>
</Style.Triggers>
</Style>
</Popup.Style>
<StackPanel>
<ListView Name="myListView"
Height="100"
MaxHeight="300"
ItemsSource="{Binding List,
UpdateSourceTrigger=PropertyChanged}"
SelectionChanged="ListView_SelectionChanged">
<ListView.ItemTemplate>
<DataTemplate>
<Label Width="100"
Height="30"
Margin="0"
Content="{Binding}"
FontFamily="Segoe UI"
FontSize="14"
Padding="5,2" />
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
<Button Width="200" Height="30" />
</StackPanel>
</Popup>
</StackPanel>
UserControl.xaml.vb
UserControl.xaml.vb
Imports System.ComponentModel
Imports System.Linq.Expressions
Imports System.Collections.ObjectModel
Class UserControl1
' Dependency Properties
Public Shared ReadOnly ListProperty As DependencyProperty = DependencyProperty.Register("List", GetType(ObservableCollection(Of Integer)), GetType(MainWindow))
Public Shared ReadOnly ValueProperty As DependencyProperty = DependencyProperty.Register("Value", GetType(Integer), GetType(MainWindow))
Public Shared ReadOnly MaxValueProperty As DependencyProperty = DependencyProperty.Register("MaxValue", GetType(Integer), GetType(MainWindow))
Public Shared ReadOnly MinValueProperty As DependencyProperty = DependencyProperty.Register("MinValue", GetType(Integer), GetType(MainWindow))
' Properties
Public Property List As ObservableCollection(Of Integer)
Get
Return DirectCast(GetValue(ListProperty), ObservableCollection(Of Integer))
End Get
Set(value As ObservableCollection(Of Integer))
SetValue(ListProperty, value)
End Set
End Property
Public Property Value As Integer
Get
Return DirectCast(GetValue(ValueProperty), Integer)
End Get
Set(value As Integer)
SetValue(ValueProperty, value)
End Set
End Property
Public Property MaxValue As Integer
Get
Return DirectCast(GetValue(MaxValueProperty), Integer)
End Get
Set(value As Integer)
SetValue(MaxValueProperty, value)
End Set
End Property
Public Property MinValue As Integer
Get
Return DirectCast(GetValue(MinValueProperty), Integer)
End Get
Set(value As Integer)
SetValue(MinValueProperty, value)
End Set
End Property
Private Sub ListView_SelectionChanged(sender As System.Object, e As System.Windows.Controls.SelectionChangedEventArgs)
Value = List(myListView.SelectedIndex)
End Sub
Private Sub UserControl1_Loaded(sender As Object, e As System.Windows.RoutedEventArgs) Handles Me.Loaded
List = New ObservableCollection(Of Integer)
' Add all available numbers into the list
For iCounter As Integer = MinValue To MaxValue
List.Add(iCounter)
Next
' Set the selected index on the list for the value
myListView.SelectedIndex = Value - MinValue
End Sub
End Class
当我测试此内容时，仅供参考出来，我自己在窗口和用户控件设置中设置了最小值和最大值。
Just for reference, when I tested this out, I set the Min and Max values myself in both the window and usercontrol setup.
推荐答案
我认为您已经完成了与我刚开始学习WPF时一样的错误。我不能保证这是造成您问题的原因，但是由于这是我唯一能看到的问题，我将解决。不幸的是，有太多糟糕的教程和快速示例显示了 UserControl.DataContext 与其自身的连接：
I think that you have made the same mistake that I used to when I first started learning WPF. I can't guarantee that this is the cause of your problem, but as it's the only one that I can see, I'll address it. Unfortunately, there are so many poor tutorials and quick examples that show the connecting of a UserControl.DataContext to itself:
DataContext="{Binding RelativeSource={RelativeSource Self}}"
或者：
DataContext = this;
现在，如果您不想想要<$将c $ c> Bind 绑定到 UserControl 外部，因为这是连接后面代码中定义的属性的快速简便的方法。但是，当您想绑定从控件外部访问属性时，会发现问题。在这些情况下（如果不是在所有情况下），应使用 RelativeSource绑定到 Bind 到属性后面的代码：
Now this is perfectly acceptable if you don't want to Bind to the UserControl externally because it's a quick and easy way to connect with properties defined in the code behind. However, when you want to Bind to the properties from outside the control, you'll find problems. In these instances (if not on all occasions), you should use a RelativeSource Binding to Bind to your code behind properties:
<TextBox Name="myTextbox" Height="30" Margin="0" FontSize="14" IsReadOnly="True"
Padding="5,2" Text="{Binding Value, RelativeSource={RelativeSource AncestorType={
x:Type UserControl1}}}" />
在此绑定中， UserControl1 是声明属性的 UserControl 的名称。这应该在所有内部 Binding 上完成。这样， DataContext 不会设置为 UserControl ，而将绑定仍会找到属性。
In this Binding, UserControl1 is the name of the UserControl that declared the properties. This should be done on all of the internal Bindings. This way, the DataContext is not set to the UserControl, but the Bindings still find the properties.
您可以找到有关 RelativeSource 从MSDN上的 RelativeSource MarkupExtension 页中。
You can find out more about RelativeSource from the RelativeSource MarkupExtension page on MSDN.
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