C# 为第二个窗口设置绑定

我有两个WPF窗口，我想将上下文设置为ViewModel，但如果我写：

this.DataContext = new myViewModel() 

在我的第二个windows cs中，它不工作。这里是我的代码。我曾尝试在XAML中放置绑定并连接上下文，但当我尝试调试它时，我得到了错误代码，该断点将无法运行

BrowseDialog.xaml

 <Window x:Class="TextalkApi.BrowseDialog"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:TextalkApi"
        mc:Ignorable="d"
        Title="BrowseDialog" Height="248.361" Width="427.459">
    <Grid>
        <Button Content="Browse" HorizontalAlignment="Left" Margin="267,11,0,0" VerticalAlignment="Top" Width="75"/>
        <TextBox x:Name="FileDialog" HorizontalAlignment="Left" Height="23" Margin="10,10,0,0" TextWrapping="Wrap" Text="{Binding webUrl}" VerticalAlignment="Top" Width="244"/>
        <Button Content="Save" HorizontalAlignment="Left" Margin="267,166,0,0" VerticalAlignment="Top" Width="75" Command="{Binding SaveCommand}" />
        <TextBox HorizontalAlignment="Left" Height="23" Margin="10,38,0,0" TextWrapping="Wrap" VerticalAlignment="Top" Width="120"/>
        <Label Content="{Binding errorMessage}" HorizontalAlignment="Left" Margin="10,167,0,0" VerticalAlignment="Top" RenderTransformOrigin="-5.611,10.822" Width="207" Height="19"/> 
    </Grid>
</Window>

BrowseDialog.xaml.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Shapes;
using System.IO;
using Data;

namespace TextalkApi
{
    /// <summary>
    /// Interaction logic for BrowseDialog.xaml
    /// </summary>
    public partial class BrowseDialog : Window
    {
        public BrowseDialog()
        {
            InitializeComponent();
            this.DataContext = new BrowseViewModel();
        }
    }
}

---

您的XAML看起来是正确的，我高度怀疑是ViewModel导致它无法工作。这样的办法应该行得通

请注意，这在很大程度上取决于BaseViewModel的实现方式。如果可能的话，你能分享这一点，这样我可以更新我的答案是正确的吗？下面是如何在视图的DataContext ViewModel中实现属性

#region Properties
    private string _webUrl;
    public string WebUrl 
    { 
        get => _webUrl;     
        set 
        {
            //This will change based on how you have implemented your BaseViewModel!
            //The method name might be different, or have different parameters!
            this.SetProperty(ref _webUrl, value, nameof(WebUrl));
            //Call the save file path validation method...
            SaveFilePath();
        }
    }

    private string _errorMessage;
    public string ErrorMessage 
    { 
        get => _errorMessage;           
        private set 
        {
            //This will change based on how you have implemented your BaseViewModel!
            //This method should call NotifyPropertyChange to notify the UI to update...
            this.SetProperty(ref _errorMessage, value, nameof(ErrorMessage));
        }
    }
#endregion

在ViewModelBase中，可以添加一个通用的SetProperty方法，然后该方法可以为您处理引发property changed事件。大概是这样的：

public class ViewModelBase : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    public void SetProperty<T>(ref T storage, T value, string propertyName)
    {
        storage = value;
        RaisePropertyChangedEvent(propertyName);
    }

    protected void RaisePropertyChangedEvent(string propertyName)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }
}

由于ViewModel中的更改，您还需要更新XAML中的绑定

<Grid>
    <Button Content="Browse" HorizontalAlignment="Left" Margin="267,11,0,0" VerticalAlignment="Top" Width="75"/>
    <TextBox x:Name="FileDialog" HorizontalAlignment="Left" Height="23" Margin="10,10,0,0" TextWrapping="Wrap" Text="{Binding WebUrl}" VerticalAlignment="Top" Width="244"/>
    <Button Content="Save" HorizontalAlignment="Left" Margin="267,166,0,0" VerticalAlignment="Top" Width="75" Command="{Binding SaveCommand}" />
    <TextBox HorizontalAlignment="Left" Height="23" Margin="10,38,0,0" TextWrapping="Wrap" VerticalAlignment="Top" Width="120"/>
    <Label Content="{Binding ErrorMessage}" HorizontalAlignment="Left" Margin="10,155,0,0" VerticalAlignment="Top" RenderTransformOrigin="-5.611,10.822" Width="207" Height="46"/>
</Grid>

---

这里的问题是没有显示错误消息吗？你能澄清一下你的问题吗。我怀疑是的，在这种情况下，在errorMessage属性的setter中没有调用NotifyPropertyChanged或类似的，我怀疑您的ViewModelBase中有一个方法可以设置属性并自动调用实现该属性的方法。是的，这与问题很接近，但断点eaven似乎没有可能被击中。谢谢您共享您的ViewModelBase，我在他们的方法中看不到引发此事件的任何内容。我将用一个简单的例子更新我的anwser。你答案的顶部我应该在哪里添加它我进入viewmodel，但就像我添加属性一样？是的，抱歉顶部是viewmodel中的属性。在标签上的XAML中，try Content={Binding errorMessage，UpdateSourceTrigger=PropertyChanged}不起作用，它不会更新，但我仍然认为该命令是错误的否？

public class ViewModelBase : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    public void SetProperty<T>(ref T storage, T value, string propertyName)
    {
        storage = value;
        RaisePropertyChangedEvent(propertyName);
    }

    protected void RaisePropertyChangedEvent(string propertyName)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }
}

<Grid>
    <Button Content="Browse" HorizontalAlignment="Left" Margin="267,11,0,0" VerticalAlignment="Top" Width="75"/>
    <TextBox x:Name="FileDialog" HorizontalAlignment="Left" Height="23" Margin="10,10,0,0" TextWrapping="Wrap" Text="{Binding WebUrl}" VerticalAlignment="Top" Width="244"/>
    <Button Content="Save" HorizontalAlignment="Left" Margin="267,166,0,0" VerticalAlignment="Top" Width="75" Command="{Binding SaveCommand}" />
    <TextBox HorizontalAlignment="Left" Height="23" Margin="10,38,0,0" TextWrapping="Wrap" VerticalAlignment="Top" Width="120"/>
    <Label Content="{Binding ErrorMessage}" HorizontalAlignment="Left" Margin="10,155,0,0" VerticalAlignment="Top" RenderTransformOrigin="-5.611,10.822" Width="207" Height="46"/>
</Grid>