Universal Windows Platform commanding with parameters [closed]

问题

How I can make parameterized commands in Universal Windows Platform without MVVM-frameworks? I was tried to implement RelayCommand class, but System.Windows.Input namespace haven't CommandManager class.

回答1:

If you don't want to use a framework, you have to implement the interface System.Windows.Input.ICommand yourself.

Command parameters can be passed by the the property CommandParameter. There is no need for a command manager. If you use a one-way binding for the parameter, the button will be enabled / disabled automatically when the binding change. For anything else raise the event CanExecuteChanged.

Of course, in a more advanced scenario, you'll have to implement some state management for the command as well, which is easier if the commands are defined in a viewmodel or use are using some kind of self implemented command manager.

Simplified example

Here a simplified example how to use a button with x:Bind binding. No view model or command manager is reuired.

Example.xaml:

<Button x:Name="Test" Command="{x:Bind FirstCommand}" CommandParameter="{x:Bind SelectedItem, Mode=OneWay">
   <TextBlock>Test</TextBlock>
</Button>

Example.xaml.cs:

public sealed partial class Example : Page {

    public SampleCommand FirstCommand { get; set; } =
        new SampleCommand();

    public object SelectedItem { get; set; }

    public StandardProjectList() {
        this.InitializeComponent();
    }

}

SampleCommand.cs:

public class SampleCommand : ICommand {

    public event EventHandler CanExecuteChanged;

    public bool CanExecute(object parameter) {
        return parameter != null;
    }   

    public void Execute(object parameter) {
        if (CanExecute(parameter))
            //...
    }   
}

来源：https://stackoverflow.com/questions/33003207/universal-windows-platform-commanding-with-parameters

标签

mvvm

uwp