Question

im passing my webservice url to my silverlight application via the parameters.

when my application launches it creates the viewmodel for the mainpage before it application_startup event is fired.

in my viewmodel constructor i have a call to my serviceagent to load some data from the webservice, but the webservice url is not initialised yet due the the viewmodel being constructed before the application_startup event is raised. whats the best way to get around this. Its a friday evening and my brain seems to be pretty fried trying to think of a good solution.

An instance of the ViewModelLocator is created in the app.xaml

<vm:ViewModelLocator x:Key="Locator" d:IsDataSource="True" />

Then in the ViewModelLocator constructor there is a call to create the main page

    public ViewModelLocator()
    {
        CreateMain();
    }

    public static void CreateMain()
    {
        if (_main == null) _main = new MainViewModel();
    }

and in my MainViewModel i make a call to my serviceagent

    public MainViewModel() : this(new MyServiceAgent()) { }

    public MainViewModel(IMyServiceAgent myServiceAgent)
    {
        if (IsInDesignMode)
        {

        }
        else
        {

            ServiceAgent = myServiceAgent;         
            ServiceAgent.GetData();

            RegisterMessageListeners();
            WireUpCommands();
        }
    }

App.xaml.cs

    public App()
    {
        Startup += Application_Startup;
        Exit += Application_Exit;
        UnhandledException += Application_UnhandledException;

        InitializeComponent();
    }

    private void Application_Startup(object sender, StartupEventArgs e)
    {
        if (e.InitParams != null && e.InitParams.Count > 0)
            ParseInitParams(e.InitParams);

        RootVisual = new MainPage();
        DispatcherHelper.Initialize();
    }

Cheeers

Answer 1

to fix my issue i had to remove the line of code from the viewmodellocator constructor that was initialising the MainViewModel

public ViewModelLocator()
{
    //CreateMain();
}