WPF MVVM dialog example

Question

Does anyone have any examples of showing a window dialog using MVVM (Prism)? - for example a configuration settings window when a command is executed.

All of the exa

Answer 1

I'm agreed, that using service to display dialog according to MVVM pattern is the most simple solution. But, I also asked myself, if there are 3 assemblies in my project Model, ViewModel, View and according to MVVM pattern assembly ViewModel has a reference to Model, and View to both Model and ViewModel where should I place DialogService class? If I will place one in the ViewModel assembly - I have no chances to create DialogView instance; on the other hand, if I will place DialogService in the View assembly, how I should inject it in my ViewModel class?

So, I would recoment look at Advanced MVVM scenarios with Prism Part: Using Interaction Request Objects

As example of this approach:

DialogViewModelBase

public abstract class DialogViewModelBase : ViewModelBase
{
    private ICommand _ok;

    public ICommand Ok
    {
        get { return _ok ?? (_ok = new DelegateCommand(OkExecute, CanOkExecute)); }
    }

    protected virtual bool CanOkExecute()
    {
        return true;
    }

    protected virtual void OkExecute()
    {
        _isSaved = true;
        Close = true;
    }

    private ICommand _cancel;

    public ICommand Cancel
    {
        get 
        {
           return _cancel ?? (_cancel = new DelegateCommand(CancelExecute, CanCancelExecute));
        }
    }

    protected virtual bool CanCancelExecute()
    {
        return true;
    }

    protected virtual void CancelExecute()
    {
        Close = true;
    }

    private bool _isSaved = false;
    public bool IsSaved
    {
        get { return _isSaved; }
    }

    private bool _close = false;

    public bool Close
    {
        get { return _close; }
        set
        {
            _close = value;
            RaisePropertyChanged(() => Close);
        }
    }
}

CreateUserStoryViewModel:

public class CreateUserStoryViewModel : DialogViewModelBase
{
    private string _name = String.Empty;

    public string Name
    {
        get { return _name; }
        set
        {
            _name = value;
            RaisePropertyChanged(() => Name);
        }
    }
}

CreateUserStoryRequest

private InteractionRequest _createUserStoryRequest;
public InteractionRequest CreateUserStoryRequest
{
    get
    {
        return _createUserStoryRequest ?? (_createUserStoryRequest = new InteractionRequest());
    }
}

CreateUserStory Command

private void CreateUserStoryExecute()
{
    CreateUserStoryRequest.Raise(new Notification()
    {
        Content = new CreateUserStoryViewModel(),
        Title = "Create User Story"
    }, 
    notification =>
                 {
                      CreateUserStoryViewModel createUserStoryViewModel =
                               (CreateUserStoryViewModel)notification.Content;
                      if (createUserStoryViewModel.IsSaved)
                      {
                         _domainContext.CreateUserStory(
new UserStory(){ Name = createUserStoryViewModel.Name, });
                      }
                 });
}

XAML: