仅在创建窗口并将其显示为对话框之后，才能设置"DialogResult".在实现WPF MVVM模式以关闭表单时 [英] Getting "DialogResult can be set only after Window is created and shown as dialog" when implementing WPF MVVM pattern for form closing

问题描述

我正在尝试为WPF表单关闭实现此 MVVM模式，该博客，我得到了System.InvalidOperationException错误消息仅在创建Window并显示为对话框之后才能设置DialogResult".当我尝试在关闭"按钮命令上设置对话框结果"时:

I am trying to implement this MVVM pattern for the WPF form closing which is also explained in this blog and I am getting System.InvalidOperationException with error message "DialogResult can be set only after Window is created and shown as dialog." when I am trying to set the Dialog Result on Close button command:

DialogResult = true;

这是我的ViewModel:

Here is my ViewModel:

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视图:

<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>

我在做什么错了?

推荐答案

仅当使用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，会出现此错误.

Setting a dialog result only works when you open your form with ShowDialog(). You get this error when you try to set the dialog result on a form opened with Show().

这篇关于仅在创建窗口并将其显示为对话框之后，才能设置"DialogResult".在实现WPF MVVM模式以关闭表单时的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！