WPF绑定文本框到字典条目 [英] WPF binding textbox to dictionary entry

问题描述

我尝试将wpf文本框绑定到viewmodel中放置的字典。视图模型用作视图的数据标签。
我发现很多例子，听起来很简单，但对我来说不行。

查看：

TextBox x：Name =txbTestGrid.Row =10Grid.Column =2Text ={Binding MyDict [First]}

ViewModel：

  public Dictionary< string，string> ; MyDict = new Dictionary< string，string> 
 {
 {First，Test1}，
 {Second，Test2} 
}; 
  

我尝试我找到的所有变体

  Text ={Binding MyDict [First]}
 Text ={Binding Path = MyDict [First]}
 Text ={Binding MyDict [First] .Text}
 Text ={Binding MyDict [First] .Value}
  

但无效，文本框为空。任何想法？

解决方案

您的代码中有一个Binding错误，因为 MyDict 不是财产。您必须绑定到属性而不是绑定到字段

$ code> System.Windows.Data错误：40：BindingExpression路径错误：'MyDict'属性在'object''''MainWindow'（Name =''）'上找不到。 BindingExpression：路径= MyDict [第一]; DataItem ='MainWindow'（Name =''）;目标元素为'TextBox'（Name ='textBox1'）;目标属性为'Text'（类型'String'）

更改MyDict 字段到属性如下所示

 私人字典< string，string> _MyDict; 
 
 public Dictionary< string，string> MyDict 
 {
 get {return _MyDict; } 
 set {_MyDict = value; } 
} 
  

在您的 ViewModel initialize MyDict。

  MyDict = new Dictionary< string，string> 
 {
 {First，Test1}，
 {Second，Test2} 
}; 
  

以下两个变体将不起作用MyDict [key]返回一个 string 和 string 没有文本或值属性。其他两个变体应该工作。

  Text ={Binding MyDict [First] .Text}
 Text ={Binding MyDict [First] .Value}
  

i try to bind a wpf textbox to a dictionary placed in a viewmodel. The viewmodel is used as datacontext for the view. I found a lot of examples and it sounds simple, but it will not work for me.

View:

TextBox x:Name="txbTest" Grid.Row="10" Grid.Column="2" Text="{Binding MyDict[First]}"

ViewModel:

public Dictionary<string, string> MyDict = new Dictionary<string, string>
        {
            {"First", "Test1"},
            {"Second", "Test2"}
        };

I try all variants i found

Text="{Binding MyDict[First]}"
Text="{Binding Path=MyDict[First]}"
Text="{Binding MyDict[First].Text}"
Text="{Binding MyDict[First].Value}"

But nothing works, textbox is empty. Any idea?

解决方案

There is a Binding error in your code because MyDict is not a property. You have to bind to a Property and not to a Field

System.Windows.Data Error: 40 : BindingExpression path error: 'MyDict' property not found on 'object' ''MainWindow' (Name='')'. BindingExpression:Path=MyDict[First]; DataItem='MainWindow' (Name=''); target element is 'TextBox' (Name='textBox1'); target property is 'Text' (type 'String')

Change the MyDict Field to a Property like shown below

    private Dictionary<string, string> _MyDict;

    public Dictionary<string, string> MyDict
    {
        get { return _MyDict; }
        set { _MyDict = value; }
    }

In the constructor of your ViewModel initialize MyDict.

        MyDict = new Dictionary<string, string>
        {
            {"First", "Test1"},
            {"Second", "Test2"}
        };

The following two variants will not work as MyDict["key"] returns a string and string does not have a Text or Value property. The other two variants should work.

Text="{Binding MyDict[First].Text}"
Text="{Binding MyDict[First].Value}"

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