Refactoring leads to Cannot resolve symbol 'RoutedUICommand'

Question

Situation :

I've started coding a model and its commands inside a WPF project, now I've decided to move this 'model' to a class library so it does not depend on any of the WPF types.

The ultimate goal is to be able to use it on another framework than WPF, Forms for instance.

For the model it was painless, there were no dependencies at all on any WPF type, however the model commands class returns a bunch of errors : Cannot resolve symbol 'RoutedUICommand'

Here's an extract of the class :

public static class MyModelCommands
{
    private static readonly RoutedUICommand _addFiles;

    static MyModelCommands()
    {
        _addFiles = new RoutedUICommand("Add files", "AddFiles", typeof (MyModelCommands));
    }

    public static RoutedUICommand AddFiles
    {
        get { return _addFiles; }
    }

    // ...
}

Looking at the RoutedUICommand documentation :

The Execute and CanExecute methods on a RoutedCommand do not contain the command logic for the command, as is the case with a typical ICommand. The Execute and CanExecute methods on a RoutedCommand do not contain the command logic for the command, as is the case with a typical ICommand.

I've come to the conclusion that I should use my own derivation of ICommand, I'd even benefit from that in the sense that I'll implement the commands logic inside the class library, which is great.

But what about the WPF project, should I create a facade of this class that encompasses these commands in RoutedUICommand(s) and update my CommandBindings to the handlers in the class library ?

Sheridan Sheridan · Accepted Answer · 2014-02-05T20:55:07

The RoutedUICommand class is a UI class that is used in views and their code behind or view models. Your model classes shouldn't have any ICommand fields or properties in them. How your models are displayed or edited in the UI is not the concern of your model classes. This is to keep the separation between your UI layer and your business model layer.

When you follow this pattern, then you can provide different UIs for the same model classes. For example, if you were to add a WinForms UI for your models, you can simply use its event system to provide the functionality, so the ICommands are not necessary. Rather than trying to re-invent the wheel with your own custom command logic, just use whatever means are available on whatever Framework you use.

Refactoring leads to Cannot resolve symbol 'RoutedUICommand'

2 Answers