WPF MVVM - global command with parameters

Question

I need to open same window for displaying reports, from many different pages, on button click. But (based on page where I open It) I need to provide which report should be displayed, title of window etc.

So I'm trying to create a global command with parameters for that, in order to avoid writing same button command in each ViewModel.

I know how to create global command:

public static class Global_commands
{
  private static readonly RoutedUICommand _reports = new RoutedUICommand("View report", "View_report", typeof(Global_commands));

  public static RoutedUICommand View_report
  {
     get{return _reports;}
  }
}

 //in App.xaml:

public App()
{
  var view_report = new CommandBinding(Global_commands.View_report, View_Report_Executed, View_Report_CanExecute);
  CommandManager.RegisterClassCommandBinding(typeof(Window), view_report);
}

private void View_Report_Executed(object sender, ExecutedRoutedEventArgs e)
{
  //...
}

But that doesn't allow me to pass a parameter, or at least I don't know how. So I can't say which report should be displayed.

Another option for commands I know is this:

public class Register_command : ICommand
{
   public event EventHandler CanExecuteChanged;
   private readonly Action<object> _execute;
   private readonly Predicate<object> _canExecute;

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

   public bool CanExecute(object parameter)
   {
      if (_canExecute == null)
           return true;
           return _canExecute(parameter);
   }

   public void Execute(object parameter)
   {
       if (_execute != null)
          _execute(parameter);
   }
}

 //in ViewModel of some window:

 public ICommand Open_report { get; set; }

 public SomeViewModel()
 {
    Open_report = new Register_command(Open_report_window, null);
 }

 //I would a method something like that - with parameters
 private void Open_report_window(object parameter)
 {
   Report_Window report_wind = new Report_Window();
   report_wind.Owner = System.Windows.Application.Current.MainWindow;

     switch (parameter)
     {
        case "1":
         report_wind.Title= "Report number 1";
         report_wind.Report_Name="Report1.rdlc";

        default:
          break;
     }
 }

In this case, my Executed method allows me to pass a parameter, but I don't know how to pass this command globally.

Can somebody show me correct approach for this ?

score 0 · Answer 1 · answered May 27 '20 at 12:49

Sorry, too fast on posting. My solution was to use e.Parameter. so first option is the one to go for me:

    public static class Global_commands
    {
      private static readonly RoutedUICommand _reports = new RoutedUICommand("View report", "View_report", typeof(Global_commands));

      public static RoutedUICommand View_report
      {
         get{return _reports;}
      }
    }

     //in App.xaml:

    public App()
    {
      var view_report = new CommandBinding(Global_commands.View_report, View_Report_Executed, View_Report_CanExecute);
      CommandManager.RegisterClassCommandBinding(typeof(Window), view_report);
    }

    private void View_Report_Executed(object sender, ExecutedRoutedEventArgs e)
    {

      Report_Window report_wind = new Report_Window();
      report_wind.Owner = System.Windows.Application.Current.MainWindow;

       switch (e.Parameter)
         {
            case "1":
             report_wind.Title= "Report number 1";
             report_wind.Report_Name="Report1.rdlc";

            default:
              break;
         }
    }

WPF MVVM - global command with parameters

1 Answers1