WPF? ViewModelBase ?? ??? ?? ??

WPF??? ?? ???(ViewModelBase)? ??? ??? ??? ????? ?? ??? ? ????. ? ??? ???? ??? ??? ????.

1. ??? ???? ??

?(?: AttributeView)?? DataContext ??? ViewModelBase ???? ????? ?????. ?? ?? ViewModelBase ??? ??? ??? ????? ?????.

2. ?? ??? ???

Binding ?? ??? ???? ??? Command ??? ViewModelBase? ??? ?? ??? ??????. ?:

<Button Command="{Binding DataInitialization}" />

3. ViewModelBase?? ?? ?? ??

ViewModelBase ????? DataInitialization ??? ICommand ?????? ????? ?????.

public ICommand DataInitialization { get; protected set; }

4. ??? ?? ??

?????? ?? ? ?? ??? ?? DataInitialization ??? ????? ???? ?? DataInitialization ??? ?????. ?:

DataInitialization = new DataInitializationCommand();

5. ??? ?? ?? ??? ??

ICommand ?????? ???? ??? ?? ?? ???? ????. ? ???? ?? ??? CanExecute ??? ?????.

6. ?? ? CanExecute ??

??? ?? ?? ????? Execute ? CanExecute ???? ????? ??? ??? ??? ?????.

?? ??:

??(XAML): (?? XAML ?? ??, ?? ?? ??? ????? ?? ??? ? ??)

<Button Content="Initialize Data" Command="{Binding DataInitialization}" />

???:

public class ViewModelBase : INotifyPropertyChanged // 需要實現(xiàn)INotifyPropertyChanged接口
{
    private ICommand _dataInitializationCommand;

    public ICommand DataInitialization
    {
        get { return _dataInitializationCommand ?? (_dataInitializationCommand = new RelayCommand(DataInitializationAction, CanDataInitialization)); }
    }

    private bool CanDataInitialization(object parameter)
    {
        //  添加你的CanExecute邏輯
        return true; 
    }

    private void DataInitializationAction(object parameter)
    {
        //  添加你的Execute邏輯
    }

    // ... INotifyPropertyChanged 實現(xiàn) ...
}

RelayCommand(??? ?? ?? ???):

public class RelayCommand : ICommand
{
    private readonly Action<object> _execute;
    private readonly Predicate<object> _canExecute;

    public RelayCommand(Action<object> execute, Predicate<object> canExecute = null)
    {
        _execute = execute;
        _canExecute = canExecute;
    }

    public bool CanExecute(object parameter) => _canExecute == null || _canExecute(parameter);

    public event EventHandler CanExecuteChanged
    {
        add { CommandManager.RequerySuggested += value; }
        remove { CommandManager.RequerySuggested -= value; }
    }

    public void Execute(object parameter) => _execute(parameter);
}

??? ??? ???? WPF? ??? ViewModelBase ???? ??? ??? ????? ???? ? ????. ?? ??? ??? INotifyPropertyChanged ????? ??? ?? ????? ???? RelayCommand ???? ???? ?? ???? ?? ???? ????. ?? ?? ??? ?? ??? ?????.

? ??? WPF ?? ???: ViewModelBase ??? ??? ????? ??? ??????? ?? ?????. ??? ??? PHP ??? ????? ?? ?? ??? ?????!