在 WPF 中获取“<属性名称> 已被“<控件名称>”错误注册

Getting "<Property Name> was already registered by "<Control Name>" error in WPF

提问by Ryan

I have a user control in WPF that has a binding to a Dependency Property. When I try to compile the app, I get a "Property Name" was already registered by "ControlName" error, and the designer shows a "Cannot create an instance of "User Control" error.

我在 WPF 中有一个用户控件，它绑定到依赖属性。当我尝试编译应用程序时，我收到一个“属性名称”已被“ControlName”错误注册，并且设计器显示“无法创建“用户控件”的实例错误。

Here is what my simple control looks like:

这是我的简单控件的样子：

ExampleUserControl.xaml:

示例用户控件.xaml：

<UserControl x:Class="ExampleApp1.ExampleUserControl"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             xmlns:local="clr-namespace:ExampleApp1"
             mc:Ignorable="d" >

    <TextBox Text="{Binding RelativeSource={RelativeSource AncestorType={x:Type local:ExampleUserControl}}, Path=SomeStringValue}" />

</UserControl>

ExampleUserControl.xaml.cs:

ExampleUserControl.xaml.cs：

public partial class ExampleUserControl : UserControl
{

    public DependencyProperty SomeStringValueProperty = DependencyProperty.Register("SomeStringValue", typeof(string), typeof(ExampleUserControl));
    public string SomeStringValue
    {
        get
        {
            return GetValue(SomeStringValueProperty) as string;
        }
        set
        {
            SetValue(SomeStringValueProperty, value);
        }
    }

    public ExampleUserControl()
    {
        InitializeComponent();
    }
}

The Main Window it's hosted in:

它托管的主窗口：

<Window x:Class="ExampleApp1.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:local="clr-namespace:ExampleApp1"
        Title="MainWindow" Height="350" Width="525">

    <StackPanel>
        <local:ExampleUserControl SomeStringValue="Test 1" />
        <local:ExampleUserControl SomeStringValue="Test 2" />
    </StackPanel>

</Window>

Here is what the designer looks like:

这是设计师的样子：

Here is what the XAML designer looks like:

XAML 设计器如下所示：

回答by Ryan

What's happening is the Dependency Property is getting Registered multiple times under the same name and owner. Dependency Properties are intended to have a single owner, and should be statically instanced. If you don't statically instance them, an attempt will be made to register them for each instance of the control.

发生的事情是依赖属性以相同的名称和所有者多次注册。依赖属性旨在拥有一个所有者，并且应该是静态实例化的。如果您不静态实例化它们，则会尝试为控件的每个实例注册它们。

Make your DependencyProperty declaration static. Change it from:

使您的 DependencyProperty 声明为静态。将其更改为：

 public DependencyProperty SomeStringValueProperty =
                             DependencyProperty.Register("SomeStringValue", 
                                                         typeof(string), 
                                                         typeof(ExampleUserControl));

To:

到：

public static DependencyProperty SomeStringValueProperty =
                             DependencyProperty.Register("SomeStringValue", 
                                                         typeof(string), 
                                                         typeof(ExampleUserControl));

回答by Declan Taylor

My error message of this type was caused by registering a dependency property with a base class

我的这种类型的错误消息是由使用基类注册依赖属性引起的

i.e this

即这个

public static readonly DependencyProperty WorkerStateProperty =
    DependencyProperty.Register("WorkerState", typeof(State), typeof(Control),
        new FrameworkPropertyMetadata(State.Stopped, new PropertyChangedCallback(OnWorkerStateChanged)));

instead of this

而不是这个

public static readonly DependencyProperty WorkerStateProperty =
    DependencyProperty.Register("WorkerState", typeof(State), typeof(WorkerControl),
        new FrameworkPropertyMetadata(State.Stopped, new PropertyChangedCallback(OnWorkerStateChanged)));

where my WorkerControl class derived from Control

我的 WorkerControl 类派生自 Control

回答by ΩmegaMan

I did a cut and paste between two controls for the dependency property and forgot to change the registered class away from the first control on the second. Hence duplication.

我在依赖属性的两个控件之间进行了剪切和粘贴，但忘记将注册的类从第二个控件中的第一个控件更改。因此重复。

 public static readonly DependencyProperty CurrentBatchProperty =
     DependencyProperty.Register(
         "CurrentBatch",
         typeof(Batch),
         typeof({--- Must be same as encompassing class --}), // Error if not set properly.
         new PropertyMetadata(null, OnCurrentBatchPropertyChanged));

For upon pasting the code, my original control was thenregistering it in two different controls and it got the squiggly line (on the placement page) and the error.

对于在粘贴代码，我原来的对照，然后对其进行注册在两个不同的控制，并得到了波浪线（放置页）和错误。