RelayCommand with parameter

Question

I have a function that returns an ICommand (RelayCommand to be precise), and to this function I need to pass some parameters. Here is the code:

private ICommand CreateSectionCommand(FilterEnum filterEnum, string title = null, string searchKey = "")
    {
        return new RelayCommand(() =>
        {
            NavigationService.Build<SearchPageViewModel>()
                             .WithParam("criteria", new Criteria
                {
                    Query = searchKey,
                    SearchFilter = filterEnum,
                    Title = title
                })
                .Navigate();
        });
    }

When I initialize the command, everything is ok, but when I click on the button for navigating, it does nothing. Most probably, the problem is that all the parameters are null because the RelayCommand is invoked on a different time of the initialization.

How can I solve this and pass the correct parameters? I cannot simply bind the CommandParameter property in the XAML.

Edit: just checked my old code, the exact same version worked on Windows 8, but my project is now Windows 8.1.

Answer 1

Try to bind those parameters (in View) to properties of Your ViewModel - I assume that parameters come from some UI elements of Your View (for example search TextBox or filter type ComboBox). Then You will be able to use them in CreateSectionCommand.

But if You can't use binding from View try this:

private Criteria commandCriteria;
private ICommand CreateSectionCommand(FilterEnum filterEnum, string title = null, string searchKey = "")
{
    commandCriteria = new Criteria
            {
                Query = searchKey,
                SearchFilter = filterEnum,
                Title = title
            };
    return new RelayCommand(() =>
    {
        NavigationService.Build<SearchPageViewModel>()
                         .WithParam("criteria",commandCriteria )
            .Navigate();
    });
}