C#, WPF, MVVM, Creating a viewmodel for message dialogs/confirmation dialogs?

Question

I am not using anything other than a simple WPF application project in visual studio. I've implemented an mvvm application.

I want to display a list of content changes made by a user. I have a main window view model and it currently just builds a strings with changes. I have objects that I can reuse to display their properties (the content).

Currently, I use a MessageBoxResult to show a really long string with the changes. This is a terrible design (I know), but I couldn't really find an answer to what class a regular wpf project has that would allow me to achieve what I want.

I know there is a popup class I can use. In practice, which is better-- another view model for the dialog, or a popup?

Can anyone provide a simple example of one of the two approaches?

Thank you in advance for your response.

Answer 1

What I've done in the past is have a simple Border control, and inside of a TextBlock and whatever Button controls I need. I bind the TextBlock.Text to a public string property named "MessageBoxMessage" which calls OnPropertyChanged() . I bind the Command of each Button to a separate public ICommand which specifies what action to take in the view model when the button is clicked. I then bind the visibility of the Border control - which contains all of the other controls I mentioned - to a Visibility property.

When I want to show a dialog, I set the MessageBoxMessage to the message I want to show, makes sure the commands are set properly, and then set the Visibility on the Border to Visibility.Visible . This shows the box (border), message, and buttons.

You can even implement a semi-transparent rectangle underneath the border (over the rest of the form) that you set to visible at the same time. This will give you the nice "form dimmed" effect and also block the normal form controls from being clicked. A general note - for this to work, these controls need to be at the very bottom of your XAML as the z-index among controls at the same level is inferred from their placement in the XAML - lower in the code is top level on the form.

Let me know if you have any questions about implementing this if it sounds like what you are looking for.