.net Maui中的ASYNCCOMMAND

Question

我似乎找不到.net Maui或.Net Maui社区工具包中的asynccommand。知道我能找到哪个软件包/名称空间？

Answer 1

https://devblogs.microsoft.com/dotnet/introducing-the-net-net-maui-community-toolkit-toolkit-preview/#what to-to-to-to-expect-in-net-net-net-maui-toolkit

.NET MAUI工具包将不包含Xamarin的MVVM功能
社区工具包，例如Asynccommand。展望未来，我们将添加
所有MVVM规格的功能
communityToolkit.mvvm。

Answer 2

即使问题已被标记为解决，也可能会从约翰·蒂里特（John Thiriet）撰写的这种解决方案中获利。我实施了它，它运行良好。
https://johnthiriet.com/moveriet.com/mvvm-mmvvm-onemvvm-oneganc-wosh-yanc-wosh-onganc-oneganc-wosh-yand-andas-yanc-wonc-with-ashync-with-ashync-async-ashync- -command/

public interface IAsyncCommand<T> : ICommand
{
    Task ExecuteAsync(T parameter);
    bool CanExecute(T parameter);
}

public class AsyncCommand<T> : IAsyncCommand<T>
{
    public event EventHandler CanExecuteChanged;

    private bool _isExecuting;
    private readonly Func<T, Task> _execute;
    private readonly Func<T, bool> _canExecute;
    private readonly IErrorHandler _errorHandler;

    public AsyncCommand(Func<T, Task> execute, Func<T, bool> canExecute = null, IErrorHandler errorHandler = null)
    {
        _execute = execute;
        _canExecute = canExecute;
        _errorHandler = errorHandler;
    }

    public bool CanExecute(T parameter)
    {
        return !_isExecuting && (_canExecute?.Invoke(parameter) ?? true);
    }

    public async Task ExecuteAsync(T parameter)
    {
        if (CanExecute(parameter))
        {
            try
            {
                _isExecuting = true;
                await _execute(parameter);
            }
            finally
            {
                _isExecuting = false;
            }
        }

        RaiseCanExecuteChanged();
    }

    public void RaiseCanExecuteChanged()
    {
        CanExecuteChanged?.Invoke(this, EventArgs.Empty);
    }

//#region Explicit implementations
    bool ICommand.CanExecute(object parameter)
    {
        return CanExecute((T)parameter);
    }

    void ICommand.Execute(object parameter)
    {
        ExecuteAsync((T)parameter).FireAndForgetSafeAsync(_errorHandler);
    }
//#endregion
}

然后，它可以像Xamarin一样在MAUI中使用。

public MyMVVM()
{
   MyCommand = new AsyncCommand(async()=> await MyMethod);
}
...
public AsynCommand MyCommand {get;}

Answer 3

安装CommunityToolKitMvvm 8.0.0

[RelayCommand]
async Task your_method (){...}

Answer 4

将asyncawaitbestpractices.mvvm nuget软件包添加到您的项目中，以使asynccommand返回。

有关更多信息，请参见GitHub项目页面： https：//github.com/github.com/github.com/brminnick/brminnick/asyncawaitbestpractices

Answer 5

1. 安装Nuget软件包communityToolkit.mvvm。
2. 声明IASYNCRELAYCOMMAND并创建一个AsyncrelayCommand的实例，就像这样：

public iaSyncrelayCommand scancommand =＆gt; this.scancommand ?? =新的asyncrelayCommand（this.scannetworksasync）;