.net - 实现 WPF MVVM 模式以关闭表单时获取 "DialogResult can be set only after Window is created and shown as dialog"

Question

我正在尝试实现 this WPF 表单关闭的 MVVM 模式也在此 blog 中进行了解释并且我收到 System.InvalidOperationException 和错误消息“DialogResult can be set only after Window is created and show as dialog.”当我尝试在关闭按钮命令上设置对话框结果时:

DialogResult = true;

这是我的 View 模型:

class MainWindowViewModel:INotifyPropertyChanged
{
    private bool? dialogResult;
    public bool? DialogResult
    {
        get { return dialogResult; }
        set
        {
            if (value != this.dialogResult)
            {
                this.dialogResult = value;
                OnPropertyChanged("DialogResult");
            }
        }
    }

    public string Text
    {
        get { return "Hello!"; }
    }

    void CloseCommandExecute()
    {
        this.DialogResult = true;
    } 

这是 XAML View :

<Window x:Class="WpfApplication.Mvvm.Windowclosing.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:local="clr-namespace:WpfApplication.Mvvm.Windowclosing"
        local:DialogCloser.DialogResult="{Binding DialogResult}"
        Title="MainWindow" Height="350" Width="525">
    <Window.DataContext>
        <local:MainWindowViewModel />
    </Window.DataContext>
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="100"/>
            <RowDefinition Height="40"/>
        </Grid.RowDefinitions>
        <TextBlock Text="{Binding Text}" Grid.Row="0"/>
        <Button Grid.Row="1" Command="{Binding CloseCommand}">Close Me</Button>
    </Grid>
</Window>

我在这里做错了什么？

Answer 1

仅当您使用 ShowDialog() 打开表单时，设置对话框结果才有效。当您尝试在使用 Show() 打开的表单上设置对话框结果时，您会收到此错误。