WPF：TextBox文本未更新 [英] WPF: TextBox Text is not updating
问题描述
我在 DataTemplate 中使用了一个用户控件，该 UserControl 包含一个 TextBox 与我的的 Value 属性（声明为。在数据模板中，我将此 Value 属性绑定到我的实际属性，即 Name （也是 DependencyProperty ）绑定UserControl DependencyProperty ）。它工作正常，我在加载时为 Name 属性分配了一个值，我的 TextBox 显示了它，我将值从更改了TextBox ，它还会更新我的 Name 属性。
现在问题出现了，当我在依赖属性中添加 PropertyChangedEventHandler 时，我检查该值是否有效，如果有效则不执行任何操作，并在无效。如果值无效，当我为它分配旧值时，属性会更新，但不会在我的 UserControl TextBox 中显示更新的值。谁能告诉我为什么？
I have a user control that i am using inside a DataTemplate, this UserControl contains a TextBox which is binded with Value property(declared as a DependencyProperty) of my UserControl. In data template I bind this Value property with my actual property say Name (also a DependencyProperty). It works properly, I assign a value to Name property while loading and my TextBox displays it, i change the value from TextBox and it updates my Name property also.
Now the problem comes while I add a PropertyChangedEventHandler in the dependency property, I check for the value if it is valid, do nothing if valid and assign old value if not valid. In case of value not valid, when I assign it that old value, property updates but it is not displaying updated value in my TextBox of UserControl. Can anyone tell me why?
XAML 我的 UserControl ：
<UserControl x:Name="usercontrol">
<StackPanel>
<TextBlock ......./>
<TextBox Binding={Binding ElementName=usercontrol, Path=Value, Mode=TwoWay}/>
</StackPanel>
</UserControl>
在 Value 后面的代码中是 DependencyProperty
我正在我的 DataTemplate 中使用它：
<HierarchicalDataTemplate DataType="{x:Type myLib:myClass}" ItemsSource="{Binding Children}">
<Expander Header="{Binding}">
<WrapPanel>
<edproperty:TextPropertyEditor Caption="Name" Value="{Binding Name, Mode=TwoWay}"/>
<edproperty:TextPropertyEditor .................../>
<edproperty:TextPropertyEditor .................../>
<edproperty:TextPropertyEditor ...................../>
</WrapPanel>
</Expander>
</HierarchicalDataTemplate>
我在 TreeView 中使用的此模板。在 TreeView 内，我在 TextBox 中输入值，该值会更新<$>的 Value 属性。 c $ c> UserControl ，依次更新 myClass 的 Name 属性，我分配了一个 PropertyChangedCallback 到我的 myClass 中的 Name 属性，执行一些验证并重新分配 OldValue 如果验证失败。它反过来也更新了 Value 属性，但是我仍然看到 TextBox 具有与我之前输入的值相同的值，而不是更新的值。
This template I am using in a TreeView. Inside TreeView I enter value in the TextBox which updates the Value property of my UserControl, that in turn updates Name property of myClass I am assigning a PropertyChangedCallback to my Name Property in myClass, performing some validation and reassigning the OldValue if the validation fails. It in turn updates Value property also, but i am still seeing that the TextBox has the same value that i entered earlier not the updated one.
public string Name
{
get
{
return (string)GetValue(NameProperty);
}
set
{
SetValue(NameProperty, value);
}
}
// Using a DependencyProperty as the backing store for Name. This enables animation, styling, binding, etc...
public static readonly DependencyProperty NameProperty =
DependencyProperty.Register("Name", typeof(string), typeof(myClass), new UIPropertyMetadata(null, OnNameChanged));
protected static void OnNameChanged(DependencyObject sender, DependencyPropertyChangedEventArgs args)
{
if(checkRequired && !IsValid(e.NewValue.ToString()))
{
checkRequired=false;
(sender as myClass).Name = args.OldValue.ToString();
}
}
private static bool IsValid(string name)
{
.............some logic here
}
推荐答案
经过大量搜索，我找到了解决问题的方法
After days of looking around and a lot of search i found the solution of my problem
完成所有验证并分配旧值并更新Dependecy属性后，我需要校准UpdateTarget（）方法，来更新我的TextBox中的值。
After all validation done and assigning old value and updating the dependecy property, i need to cal UpdateTarget() method, to Update the value in my TextBox.
这是对解决方案的更好解释
This is what explains the solution better
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