Question

我无法获取数据绑定到UI。

问题
我是否必须实现DependencyProperty或INotifyPropertyChanged？它简单的数据绑定我想我不必使用上面的属性。

XMAL CODE

<Window x:Class="Pr.child"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
     xmlns:src="clr-namespace:Pr" 
     xmlns:diag="clr-namespace:System.Diagnostics;assembly=WindowsBase"
     Title="" Height="327" Width="683" WindowStartupLocation="CenterOwner">
     <Window.Resources>
        <ObjectDataProvider x:Key="Obj" ObjectType="{x:Type  src:test}" MethodName="getinfo" />
      </Window.Resources>
      <Label  x:Name="lblTest" Content="{Binding Source={StaticResource Obj},diag:PresentationTraceSources.TraceLevel=High}"</Label>
      <Button  Name="btnOK" Click="btnOK_Click">OK</Button>

代码背后

主Windows类

public partial class Window1 : Window
{
   child w = new child();
}

子窗口类

public partial class child : Window
{
     public child ()
     {
         InitializeComponent();
     }
     private void btnOK_Click(object sender, RoutedEventArgs e)
     {
         RunTest runTest = new RunTest();
     }
 }

RunTest runTest

 class RunTest
 { 
     public RunTest()
     {
         test t = new test();
         t.info = "test info";
         t.getinfo();
     }
 }

测试类

class test
{
     public string info { get; set; }
     public string getinfo()
     {
        return info;
     }
}

调试信息

System.Windows.Data Warning: 52 : Created BindingExpression (hash=44780731) for Binding (hash=63630067)
System.Windows.Data Warning: 54 :   Path: ''
System.Windows.Data Warning: 56 : BindingExpression (hash=44780731): Default mode resolved to OneWay
System.Windows.Data Warning: 57 : BindingExpression (hash=44780731): Default update trigger resolved to PropertyChanged
System.Windows.Data Warning: 58 : BindingExpression (hash=44780731): Attach to System.Windows.Controls.Label.Content (hash=1867017)
System.Windows.Data Warning: 63 : BindingExpression (hash=44780731): Resolving source 
System.Windows.Data Warning: 66 : BindingExpression (hash=44780731): Found data context element: <null> (OK)
System.Windows.Data Warning: 73 : BindingExpression (hash=44780731): Use Data from ObjectDataProvider (hash=16906910)
System.Windows.Data Warning: 74 : BindingExpression (hash=44780731): Activate with root item <null>
System.Windows.Data Warning: 100 : BindingExpression (hash=44780731): Replace item at level 0 with <null>, using accessor {DependencyProperty.UnsetValue}
System.Windows.Data Warning: 97 : BindingExpression (hash=44780731): GetValue at level 0 from <null> using <null>: <null>
System.Windows.Data Warning: 76 : BindingExpression (hash=44780731): TransferValue - got raw value <null>
System.Windows.Data Warning: 85 : BindingExpression (hash=44780731): TransferValue - using final value <null>

Answer 1

这似乎有道理。您的ObjectDataProvider正在创建 new test，并在其上调用getinfo方法。这是null，因为没有任何机会在该新实例上设置信息，实际上您的代码甚至没有对它的引用。

因此标签正确显示了您的跟踪所同意的null值。

如果希望UI对其他对绑定对象所做的更改做出反应，则只需要实现INPC或使用DependencyObjects。但是将某些属性绑定到！

会有所帮助

Answer 2

我在15分钟前遇到了这种情况。您需要实现DependencyProperty

数据绑定在WPF中不起作用

2 个答案: