WPF 数据绑定与 ResourceDictionary MVVM

WPF Data binding with ResourceDictionary MVVM

提问by shadox

I'm trying to bind a View with a ViewModel within ResourceDictionary but it does not work.

我正在尝试将 View 与 ResourceDictionary 中的 ViewModel 绑定，但它不起作用。

The application is very simple window with 2 textboxes. When I type text to textbox1, atutomatically, textbox2 must get the same text. Of course my textboxes from the View have to be binded to my properties in ViewModel.

该应用程序是一个非常简单的窗口，带有 2 个文本框。当我向 textbox1 键入文本时，自动地，textbox2 必须获得相同的文本。当然，View 中的文本框必须绑定到 ViewModel 中的属性。

I'm new to WPF and the way I started to bind Views and ViewModels was in the codebehind of a View:

我是 WPF 的新手，我开始绑定视图和视图模型的方式是在视图的代码隐藏中：

DataContext = new MyViewModel();

Now I'm trying to achieve a cleaner separation. My code is

现在我正在努力实现更清晰的分离。我的代码是

App.xaml:

应用程序.xaml：

<Application x:Class="NavigationCleanBinding.App"
         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         StartupUri="/Views/MainWindowView.xaml">
    <Application.Resources>
        <ResourceDictionary Source="MainResourceDictionary.xaml" />
    </Application.Resources>
</Application>

MainResourceDictionary.xaml:

MainResourceDictionary.xaml：

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xamlpresentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:Views="clr-namespace:NavigationCleanBinding.Views"
    xmlns:ViewModels="clr-namespace:NavigationCleanBinding.ViewModels">

    <DataTemplate DataType="{x:Type ViewModels:MainWindowViewModel}">
        <Views:MainWindowView />
    </DataTemplate>

</ResourceDictionary>

MainWindowView.xaml:

主窗口视图.xaml：

<Window x:Class="NavigationCleanBinding.Views.MainWindowView"
    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>
    <TextBox Height="23" HorizontalAlignment="Left" Margin="61,14,0,0" 
             Name="textBox1" VerticalAlignment="Top" Width="120" 
             Text="{Binding TestData, Mode=TwoWay,
             UpdateSourceTrigger=PropertyChanged}"/>
    <Label Content="Test:" Height="28" HorizontalAlignment="Left" Margin="12,12,0,0"
      Name="label1" VerticalAlignment="Top" Width="43" />
    <Label Content="Result:" Height="28" HorizontalAlignment="Left" Margin="10,46,0,0"
      Name="label2" VerticalAlignment="Top" />

    <TextBox Height="23" HorizontalAlignment="Left" Margin="61,48,0,0"
             Name="textBox2" VerticalAlignment="Top" Width="120" 

             Text="{Binding TestData, Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}"/>
    </Grid>
</Window>

MainWindowViewModel:

主窗口视图模型：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace NavigationCleanBinding.ViewModels
{
    class MainWindowViewModel
    {
        private String _testData;
        public String TestData
        {
            get { return _testData; }
            set { _testData = value; }
        }

        private MainWindowViewModel()
        {
            _testData = null;
        }
    }
}

UPDATE:

更新：

I changed property TestData to this:

我将属性 TestData 更改为：

public String TestData
    {
        get { return _testData; }
        set
        { 
            _testData = value;
            OnPropertyChanged("TestData");

        }
    }

And implemened the INotifyPropertyChanged like this:

并像这样实现了 INotifyPropertyChanged：

public event PropertyChangedEventHandler PropertyChanged;
    private void OnPropertyChanged(String propertyName)
    {
        PropertyChangedEventHandler handler = PropertyChanged;
        if (handler != null)
        {
            handler(this, new PropertyChangedEventArgs(propertyName));
        }
    }

采纳答案by TheZenker

so user1064519 was on the right track:

所以 user1064519 是在正确的轨道上：

• the View needs to be a UserControl, not a Window, as it is hosted in the MainWindow

• the ViewModel needs to be loaded into the MainWindow, this is what triggers the DataTemplateto be discovered and loaded.

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

• View 需要是 a UserControl，而不是 a Window，因为它托管在 MainWindow 中

• ViewModel 需要加载到 MainWindow 中，这是触发DataTemplate被发现和加载的原因。

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

After that you should be up and running. I have posted an in-depth example here: wpf bootstrapping datatemplates--the chicken and the egg

之后，您应该启动并运行。我在这里发布了一个深入的例子：wpf bootstrapping datatemplates--the chicken and the egg

回答by Kamolas81

Your ViewModel must implement the interface INotifyPropertyChangedand raise a PropertyChangedevent when any binded property value changes, so that your view can know that changes ocurred.

您的 ViewModel 必须实现该接口INotifyPropertyChanged并PropertyChanged在任何绑定的属性值更改时引发事件，以便您的视图可以知道发生了更改。

回答by user1064519

DataTemplate sholudnt contain window, it can contains any kind of control.

DataTemplate 不应该包含窗口，它可以包含任何类型的控件。

DataTemplate :

数据模板：

 <DataTemplate DataType="{x:Type ViewModels:MainWindowViewModel}">
        <Views:MainWindowView />
 </DataTemplate>

UserControl :

用户控制：

    <UserControl x:Class="NavigationCleanBinding.Views.MainView"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Height="350" Width="525">

<Grid>
    <TextBox Height="23" HorizontalAlignment="Left" Margin="61,14,0,0" 
             Name="textBox1" VerticalAlignment="Top" Width="120" 
             Text="{Binding TestData, Mode=TwoWay,
             UpdateSourceTrigger=PropertyChanged}"/>
    <Label Content="Test:" Height="28" HorizontalAlignment="Left" Margin="12,12,0,0"
      Name="label1" VerticalAlignment="Top" Width="43" />
    <Label Content="Result:" Height="28" HorizontalAlignment="Left" Margin="10,46,0,0"
      Name="label2" VerticalAlignment="Top" />

    <TextBox Height="23" HorizontalAlignment="Left" Margin="61,48,0,0"
             Name="textBox2" VerticalAlignment="Top" Width="120" 

             Text="{Binding TestData, Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}"/>
    </Grid>
</UserControl>

Window :

窗户 ：

 <Window x:Class="NavigationCleanBinding.Views.MainWindowView"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="MainWindow" Height="350" Width="525">

<ContentControl Content={Binding}/>
</Window>