[英]How to take a WPF CommandParameter to the ViewModel in MVVM?
我希望有人可以在這里幫助我。 簡化了發布代碼。
我們有一個帶有菜單的主窗口(MvvmTestView),還有一個包含多個選項卡的第二個窗口(SettingsView)。 我可以打開SettingsView窗口。 我什至可以通過在代碼中進行設置來選擇要打開的標簽頁。
如何從XAML代碼中使用命令參數獲取正確的值,以便打開正確的選項卡?
MvvmTestView.xaml:
<Window x:Class="MvvmTest.Views.MvvmTestView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:vm="clr-namespace:MvvmTest.ViewModels"
WindowStartupLocation="CenterScreen"
Title="MvvmTestView"
Height="500"
Width="500">
<Window.DataContext>
<vm:MvvmTestViewModel/>
</Window.DataContext>
<Grid>
<DockPanel>
<Menu>
<MenuItem Header="Menu">
<MenuItem
Header="Tab01"
Command="{Binding SettingsViewCommand}"
CommandParameter="0"/>
<MenuItem
Header="Tab02"
Command="{Binding SettingsViewCommand}"
CommandParameter="1"/>
</MenuItem>
</Menu>
</DockPanel>
<DockPanel>
<Label Content="MainView" HorizontalAlignment="Center" VerticalAlignment="Center"/>
</DockPanel>
</Grid>
</Window>
SettingView.xaml
<Window x:Class="MvvmTest.Views.SettingsView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:tabData="clr-namespace:MvvmTest.Views"
xmlns:vm="clr-namespace:MvvmTest.ViewModels"
WindowStartupLocation="CenterScreen"
Title="SettingsView"
Height="400"
Width="400">
<Window.DataContext>
<vm:MvvmTestViewModel/>
</Window.DataContext>
<Grid>
<TabControl
SelectedIndex="{Binding SettingsSelectedIndex, Mode=TwoWay}">
<tabData:Tab01View/>
<tabData:Tab02View/>
</TabControl>
</Grid>
</Window>
SettingsViewModel.cs
using System.ComponentModel;
namespace MvvmTest.ViewModels
{
public class SettingsViewModel : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
private void OnPropertyChanged(string property)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(property));
}
private int _settingsSelectedIndex;
public int SettingsSelectedIndex
{
get
{
return _settingsSelectedIndex;
}
set
{
_settingsSelectedIndex = value;
OnPropertyChanged("SettingsSelectedIndex");
}
}
}
}
MvvmTestViewModel.cs
using MvvmTest.Commands;
using MvvmTest.Views;
using System.ComponentModel;
using System.Windows.Input;
namespace MvvmTest.ViewModels
{
internal class MvvmTestViewModel : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
private void OnPropertyChanged(string propertyName)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
private SettingsViewModel SettingsViewModel;
public MvvmTestViewModel()
{
SettingsViewModel = new SettingsViewModel();
SettingsViewCommand = new SettingsViewCommand(this);
}
public ICommand SettingsViewCommand
{
get;
private set;
}
public void SettingsWindow()
{
SetIndex();
SettingsView settingsView = new SettingsView()
{
DataContext = SettingsViewModel
};
settingsView.ShowDialog();
}
public int SetIndex()
{
SettingsViewModel.SettingsSelectedIndex = 1;
return SettingsViewModel.SettingsSelectedIndex;
}
}
}
SettingsViewCommand.cs
using MvvmTest.ViewModels;
using System;
using System.Windows.Input;
namespace MvvmTest.Commands
{
internal class SettingsViewCommand : ICommand
{
private MvvmTestViewModel settingsViewModel;
public SettingsViewCommand(MvvmTestViewModel settingsViewModel)
{
this.settingsViewModel = settingsViewModel;
}
public event EventHandler CanExecuteChanged
{
add
{
CommandManager.RequerySuggested += value;
}
remove
{
CommandManager.RequerySuggested -= value;
}
}
public bool CanExecute(object parameter)
{
return true;
}
public void Execute(object parameter)
{
settingsViewModel.SettingsWindow();
}
}
}
我建議避免創建多個命令類,例如SettingsViewCommand : ICommand
。 代替使用一些通用的命令類(例如RelayCommand
從MvvmFoundation NuGet包)
假設您將MvvmFoundation添加到您的項目中,則重構MvvmTestViewModel類,如下所示:
internal class MvvmTestViewModel : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
private void OnPropertyChanged(string propertyName)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
private SettingsViewModel SettingsViewModel;
public MvvmTestViewModel()
{
SettingsViewModel = new SettingsViewModel();
SettingsViewCommand = new RelayCommand<int>(SettingsWindow);
}
public ICommand SettingsViewCommand
{
get;
private set;
}
public void SettingsWindow(int index)
{
SettingsViewModel.SettingsSelectedIndex = index;
SettingsView settingsView = new SettingsView()
{
DataContext = SettingsViewModel
};
settingsView.ShowDialog();
}
}
視圖中的CommandParameter傳遞給viewModel中的SettingsWindow
方法,並用於更改所選索引
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.