Accessing User Application Settings in a WPF Prism 4 module

I have developed a Microsoft Prism 4.0 application and I am struggling to understand how to make the user application setting functionality available to modules.

e.g. a Prope开发者_JS百科rties.Settings.Default.MyProperty.

I can define a simple class that gets populated via the bootloader (which does have a handle to the properties) and inject that into the modules but If I want to save a change of property, I need believe I need a handle to the Properties.Settings context which is not available to my modules (which are simple class libraries).

Your scenario sounds like the perfect reason to use a "Service" class. Create an interface and class called IUserSettingsService and UserSettingsService that has the information (or can load and save it from where it is stored).

Read Chapter 3 of the Prism 4.0 help file, Managing Dependencies Between Components, Registering Types with (either Unity or MEF, depending on what you are using as your DI Container).

Then, in your ViewModel that needs the user settings, locate and use your service. In MEF, it is as simple as adding a property of type IUserSettingsService with an [Import] attribute, or using [ImportingConstructor] and having a parameter of type IUserSettingsService. With Unity, you access the service through the container. See Chapter 10 of the Prism help file - Advanced MVVM Scenarios.

Added after comment discussion: Because you need your service to be in the context of your main application, you can implement your service class there. Create the interface for your service in a shared library that can be used by both the main project and your modules. Finally, load the service in the bootloader class instead of in a module.