How to call RaiseCanExecuteChanged for all DelegateCommand and DelegateCommand<T> in base ViewModel Class

Question

I am developing a WPF application using Prism and MVVM.

One of the requirements of the application is ability to login as different user (with different permissions).

Now most of the permissions are simple allow or disallow display particular view. All of them are implemented as DelegateCommand or sometime as DelegateCommand<T>

CanExecute for those commands returns true if user has permission to display particular view. Also I have a singleton Sessionmanager that holds user information and permissions.

When user logged in I am firing an event using EventAggregator. in the base Class for all ViewModels I am subscribing to that event and using reflection loop through all public properties of VM that of type DelegateCommand and call RaiseCanExecuteChanged for that command.

        Type myType = this.GetType();
        IList<PropertyInfo> props = new List<PropertyInfo>(myType.GetProperties());

        foreach (PropertyInfo prop in props)
        {
            if (prop.PropertyType == typeof(DelegateCommand))
            {
                var cmd = (DelegateCommand)prop.GetValue(this, null);
                cmd.RasieCanExecuteChanged();
            }

        }

This works well for all non-generics DelegateCommand properties but of course does not affect DelegateCommand<T> .

My question is How to determine that property is of type DelegateCommand<T> and cast to that particular type to be able to call RasieCanExecuteChanged?

Answer 1

You can check whether the property's type derives from DelegateCommandBase, and if so - cast it to DelegateCommandBase and call RaiseCanExecuteChanged.

Type myType = this.GetType();
IList<PropertyInfo> props = new List<PropertyInfo>(myType.GetProperties());

foreach (PropertyInfo prop in props)
{
    if (prop.PropertyType.IsSubclassOf(typeof(DelegateCommandBase)))
    {
        var cmd = (DelegateCommandBase)prop.GetValue(this, null);
        cmd.RaiseCanExecuteChanged();
    }
}