MVVM pattern & Silverlight commands

Hi I'm new to silverlight and MVVM logic, I've readed many articles, blogs and etc ..., but many things they've explained are about how to dealing with database operation. Let's say I have a image control and button which should upload a file and also shows selected picture in appropriate control. I don't know how to do this with MVVM pattern. I don't want you to describe how to upload file with silverligh开发者_高级运维t, actually the problem is I don't know how should I access to image control in ViewModel class to set its source property.

Any advice will be grateful Best Regards.

You don't access controls in the view-model, you expose properties.

The view, in turn, binds to the properties exposed by the view-model. In MVVM, the view's DataContext is set to a view-model.

View:

<Window … namespaces, etc. />
    <Grid>
        <TextBox Text={Binding InputText, Mode=TwoWay}
    </Grid>
</Window>

ViewModel:

public class MyViewModel : INotifyPropertyChanged
{
    string _text = "Enter text here";
    public string Text
    {
        get { return _text; }
        set 
        { 
            _text = value;
            // raise property change notification
        }
    }

    // implement INPC so the view will know when the view-model has changed
}

Now if you set the view window's DataContext property to an instance of MyViewModel, the textbox will contain the text "Enter text here," because its Text property is bound to the InputText property. If you type something else in the textbox, the view-model's InputText property will be updated to that value.