MVVM UI update after command executed dialog closes

Hey a similar question has been asked before, but none that answers mine exactly.

I have an MVVM aplication that includes an "Options" button - click this and the options dialog opens - this is done via a command.

Once the user has saved their options, I want to tell the main shell to reload its options. What is the best way of doing this?

My button looks like this:

<Button Width="50" Command="{Binding SettingsCommand}" CommandParameter="" ...>
    <Image Source="Images/Settings.png" Width="16" 开发者_运维问答Height="16" />
</Button>

Thanks, Dave.

The standard way is to implement INotifyPropertyChanged on your viewmodel, and have your command fire the PropertyChanged event after it's done changing properties (which in this case would be after the dialog closes). When you fire PropertyChanged, your bindings will read the new property values.

main shell to reload its options

Thats usualy acieved using DataBinding. When you are closing this dialog, simply update values in your ViewModel and it should bind to View easily. It looks, like your understanding of MVVM is little wrong.

I suggest having an OptionsService that the ViewModel uses within the Dialog. Save changes to the service and if any dependent VM's need to change the display state based on the options change then they register (via an event) on the service that the options have changed. The service would also have a way to get the options data as well.

If you use Dependency Injection then this should be straight forward as you can inject an IOptionsService into all the ViewModels.