TextBlock中的绑定在WPF中不起作用 [英] Binding in TextBlock doesn't work in WPF

问题描述

我想动态地更改我的Class中的 TextBlock 文本。

XAML代码：

  < TextBlock Name =Footer_textText =/> 
  

C＃：

  string footerMainMenuText =设置; 
 Binding set = new Binding（）; 
 set.Mode = BindingMode.OneWay; 
 set.Source = footerMainMenuText; 
 Footer_text.DataContext = footerMainMenuText; 
 Footer_text.SetBinding（TextBlock.TextProperty，set）; 
  

我检查了最后一行，而$ code> Footer_text.Text 设置正确。 （ Footer_text.Text =设置），但在我的应用程序中 TextBlock 不显示设置。这里有什么问题？

解决方案

如果你有约束力 - 为什么不只是在XAML中做？看看你的代码，这是没有意义的 - 你可能只是去

  Footer_text.Text =设置;你应该理想地在XAML中做到这一点，或至少提供一些绑定到
的东西。 
 
 
 < TextBlock Text ={Binding SomeProperty}/> 
  
我不知道为什么你会绑定一个字符串在自己的东西...你有没有需要绑定到文本属性的对象？
 
 
 
还使用
  Binding（）
  
这是做什么的？空白路径？不知道绑定目标是什么吗？你尝试过
  Binding（）
  
代替？
 
 
 
编辑：
 
 
 
此外，您的绑定不更新控件的原因可能是因为您没有绑定到实现INotifyPropertyChanged或类似接口的对象。控件需要知道值何时发生变化，所以我想象的是，绑定到'string'的时候不会给TextBlock提供正确的通知。
 
 
 
编辑2 ：
 
 
 
这是绑定工作的一个快速例子：
 
 
 
我的窗口类Window.cs：
 < Window x：Class =WpfApplication1.MainWindow
 xmlns =http://schemas.microsoft.com/ winfx / 2006 / xaml / presentation
 xmlns：x =http://schemas.microsoft.com/winfx/2006/xaml
 Title =MainWindowHeight =350Width = 525> 
< Grid> 
< StackPanel> 
< TextBlock x：Name =txtNameText ={Binding Name}>< / TextBlock> 
< Button Click =Button_Click>点击我1< / Button> 
< Button Click =Button_Click_1>点击我2< / Button> 
< / StackPanel> 
< / Grid> 
< / Window> 
  
 Window.xaml.cs中的代码
  public partial class MainWindow：Window 
 {
 SomeObjectClass obj = new SomeObjectClass（）; 
 public MainWindow（）
 {
 InitializeComponent（）; 
 
 txtName.DataContext = obj; 
} 
 
 private void Button_Click（object sender，RoutedEventArgs e）
 {
 obj.Name =Hello World; 
} 
 
 private void Button_Click_1（object sender，RoutedEventArgs e）
 {
 obj.Name =Goobye World; 
} 
} 
  
要绑定到的对象（使用INotifyPropertyChanged） p> 
 
 
  class SomeObjectClass：INotifyPropertyChanged 
 {
 private string _name =hello; 
 public string Name 
 {
 get 
 {
 return _name; 
} 
 set 
 {
 _name = value; 
 OnPropertyChanged（Name）; 
} 
} 
 
 public event PropertyChangedEventHandler PropertyChanged; 
 
 public void OnPropertyChanged（string PropertyName）
 {
 if（PropertyChanged！= null）
 PropertyChanged（this，new PropertyChangedEventArgs（PropertyName））; 
} 
} 
  
点击按钮更改SomeObject.Name，但它更新文本框。
 
I want to dynamically change TextBlock text in my Class.  

XAML-Code:
<TextBlock Name="Footer_text"  Text=""/>
C#:
string footerMainMenuText = "Setting";
Binding  set = new Binding("");
set.Mode = BindingMode.OneWay;
set.Source = footerMainMenuText;
Footer_text.DataContext = footerMainMenuText;
Footer_text.SetBinding(TextBlock.TextProperty, set);
I checked last line, and the Footer_text.Text is set correctly. ( Footer_text.Text="Setting"), but TextBlock in my application doesnt show "Setting". What is the problem here? 
解决方案
If you are binding - why not just do it in XAML instead? Looking at your code it's kind of pointless - you might as well just go 
Footer_text.Text = "Setting";
You should ideally do it in XAML or at least provide something for it to bind to
<TextBlock Text="{Binding SomeProperty}" />
I'm not sure why you would bind a 'string' on it's own to anything...do you have an object which you need to bind to the text property?

Also using
Binding("")
What does that do? A blank path? Not sure what the binding target would be there... have you tried
Binding()
instead?

Edit:

Also the reason why your binding is not updating the control, is probably because you haven't bound to an object which implements INotifyPropertyChanged or a similar interface. The controls need to know when values have changed, so I'd imagine that binding to 'string' isn't giving the TextBlock the proper notification when it changes

Edit 2:

Here is a quick example of binding working:

My window class Window.cs:
<Window x:Class="WpfApplication1.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="MainWindow" Height="350" Width="525">
    <Grid>
        <StackPanel>
        <TextBlock x:Name="txtName" Text="{Binding Name}"></TextBlock>
            <Button Click="Button_Click">Click me 1</Button>
            <Button Click="Button_Click_1">Click me 2</Button>
        </StackPanel>
    </Grid>
</Window>
The code behind in Window.xaml.cs
public partial class MainWindow : Window
{
    SomeObjectClass obj = new SomeObjectClass();
    public MainWindow()
    {
        InitializeComponent();

        txtName.DataContext = obj;
    }

    private void Button_Click(object sender, RoutedEventArgs e)
    {
        obj.Name = "Hello World";
    }

    private void Button_Click_1(object sender, RoutedEventArgs e)
    {
        obj.Name = "Goobye World";
    }
}
The object to bind to (with INotifyPropertyChanged)
class SomeObjectClass : INotifyPropertyChanged
{
    private string _name = "hello";
    public string Name
    {
        get
        {
            return _name;
        }
        set
        {
            _name = value;
            OnPropertyChanged("Name");
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;

    public void OnPropertyChanged(string PropertyName)
    {
        if (PropertyChanged != null)
            PropertyChanged(this, new PropertyChangedEventArgs(PropertyName));
    }
}
Clicking the buttons changes SomeObject.Name, but it updates the textbox.

                        
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