Binding.Path结合
Binding.Path结合
提问于 2017-01-05 10:02:49
我怎样才能实现以下的目标
<CheckBox Content="{Binding Caption}">
<CheckBox.IsChecked>
<Binding Path="{Binding PropertyName}"
Source="{Binding Source}" />
</CheckBox.IsChecked>
</CheckBox>哪里
public class ViewModel
{
public string Caption { get; } = "Test";
public string PropertyName { get; } = nameof(Test.Property);
public object Source { get; } = new Test();
}
public class Test
{
public bool Property { get; set; } = false;
}其思想是通过属性为绑定提供Path和Source (设计时未知)。
当前，此抛出异常位于<Binding Path=行。
不能在“绑定”类型的“路径”属性上设置“绑定”。“绑定”只能设置在DependencyProperty的DependencyObject上。
回答 3
Stack Overflow用户
回答已采纳
发布于 2017-01-05 11:02:23
我要做的就是行为。下面的行为将获得源和路径，并相应地更新IsChecked属性的绑定。你可以扩展这个以满足你的需要。现在，这仅限于IsChecked属性，您可以编写支持所有属性的泛型代码。
public class CheckBoxCustomBindingBehavior : Behavior<CheckBox>
{
protected override void OnAttached()
{
base.OnAttached();
}
public object Source
{
get
{
return (object)GetValue(SourceProperty);
}
set
{
SetValue(SourceProperty, value);
}
}
// Using a DependencyProperty as the backing store for Source. This enables animation, styling, binding, etc...
public static readonly DependencyProperty SourceProperty =
DependencyProperty.Register("Source", typeof(object), typeof(CheckBoxCustomBindingBehavior), new PropertyMetadata(null, OnSourceChanged));
private static void OnSourceChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
(d as CheckBoxCustomBindingBehavior).ModifyBinding();
}
public string Path
{
get
{
return (string)GetValue(PathProperty);
}
set
{
SetValue(PathProperty, value);
}
}
// Using a DependencyProperty as the backing store for Path. This enables animation, styling, binding, etc...
public static readonly DependencyProperty PathProperty =
DependencyProperty.Register("Path", typeof(string), typeof(CheckBoxCustomBindingBehavior), new PropertyMetadata(string.Empty, OnPathChanged));
private static void OnPathChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
(d as CheckBoxCustomBindingBehavior).ModifyBinding();
}
private void ModifyBinding()
{
var source = Source ?? AssociatedObject.DataContext;
if (source != null && !string.IsNullOrEmpty(Path))
{
Binding b = new Binding(Path);
b.Source = source;
AssociatedObject.SetBinding(CheckBox.IsCheckedProperty, b);
}
}
}以及Xaml的使用，
<CheckBox xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity">
<i:Interaction.Behaviors>
<local:CheckBoxCustomBindingBehavior Path="{Binding SelectedPath}" Source="{Binding}" />
</i:Interaction.Behaviors>
</CheckBox>SelectedPath来自于模型，而这就是我存储属性名称的地方。
注意:您将需要交互式程序集。
Stack Overflow用户
发布于 2017-01-05 11:13:36
必须在编译时知道源属性的名称，才能在XAML中设置绑定：
<CheckBox Content="{Binding Caption}">
<CheckBox.IsChecked>
<Binding Path="Source.Property" />
</CheckBox.IsChecked>
</CheckBox>正如错误消息告诉您的，不能将某些内容绑定到绑定的Path属性。
如果在设计时不知道要绑定到的属性的名称，可以通过编程方式设置绑定：
<CheckBox x:Name="ck" Content="{Binding Caption}" />ViewModel vm = new ViewModel();
ck.DataContext = vm;
ck.SetBinding(CheckBox.IsCheckedProperty, new Binding(vm.PropertyName) { Source = vm.Source });但是，在纯XAML中无法做到这一点。记住，XAML是一种标记语言。
Stack Overflow用户
发布于 2017-01-05 14:45:48
在看到@WPFUser one之后，回答有点晚，但它支持任何属性，我个人不喜欢混合依赖关系：
public class DynamicBinding
{
public static object GetSource(DependencyObject obj) => (object)obj.GetValue(SourceProperty);
public static void SetSource(DependencyObject obj, object value) => obj.SetValue(SourceProperty, value);
public static readonly DependencyProperty SourceProperty =
DependencyProperty.RegisterAttached("Source", typeof(object), typeof(DynamicBinding), new PropertyMetadata(null, (d, e) => SetBinding(d)));
public static string GetProperty(DependencyObject obj) => (string)obj.GetValue(PropertyProperty);
public static void SetProperty(DependencyObject obj, string value) => obj.SetValue(PropertyProperty, value);
public static readonly DependencyProperty PropertyProperty =
DependencyProperty.RegisterAttached("Property", typeof(string), typeof(DynamicBinding), new PropertyMetadata(null, (d, e) => SetBinding(d)));
public static string GetTarget(DependencyObject obj) => (string)obj.GetValue(TargetProperty);
public static void SetTarget(DependencyObject obj, string value) => obj.SetValue(TargetProperty, value);
public static readonly DependencyProperty TargetProperty =
DependencyProperty.RegisterAttached("Target", typeof(string), typeof(DynamicBinding), new PropertyMetadata(null, (d, e) => SetBinding(d)));
static void SetBinding(DependencyObject obj)
{
var source = GetSource(obj);
var property = GetProperty(obj);
var target = GetTarget(obj);
// only if all required attached properties values are set
if (source == null || property == null || target == null)
return;
BindingOperations.SetBinding(obj, DependencyPropertyDescriptor.FromName(target, obj.GetType(), obj.GetType()).DependencyProperty,
new Binding(property) { Source = source });
}
}用途如下：
<CheckBox Content="{Binding Caption}"
local:DynamicBinding.Property="{Binding PropertyName}"
local:DynamicBinding.Source="{Binding Source}"
local:DynamicBinding.Target="IsChecked" />Target可以是控件的任何依赖项属性。它是一个普通的字符串，不知道如何改进它，以获得intellisense的帮助时，进入它。
ToDo:如果更改了Target (它将反映对Source或Property所做的更改)，则不会删除绑定，不支持多个动态绑定(例如，对控件的不同属性)。
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/41482038
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