Channel 9 Forums - Tech Off - Where can I find some blogs or video training on doing mutliple windows with WPF?

Tech Off - Where can I find some blogs or video training on doing mutliple windows with WPF?

RodAtWork — Mon, 12 Dec 2011 18:24:12 GMT

For a while now I've been struggling with learning the MVVM design pattern with WPF. I've found lots of blogs and video training which all involve 1 window, or page, and that's it. I've found some which do multiple pages, but for the most part they're all Windows Phone examples, however I'm going to be working on a major rewrite of a legacy VB6 app we're translating into a WPF app. This is a major LOB app, which deals with a lot of data, and we're going to have to display this data on several windows (or pages, although I think this app would be better suited to use windows rather than be a page-based app). You see, the major problem is learning how to pass data from one window to another. We've been investigating MVVM Light, which seems possible but we're still not finding really good blogs or video training on it. All of them we've found are related only for doing Windows Phone apps. That's nice and all, but don't help us. Especially since going through the code in these blogs they appear not to help us see how to pass information between windows, with the view model, etc. I'd really like some links that would point to what we could use to better learn. And we're getting to the point of possibly considering using Prism instead of MVVM Light, if Prism will better help us know to work with multiple windows, or perhaps multiple views on a single windows (perhaps in lots of user controls, etc). If we do consider Prism, is there good online training on it (either blogs or videos)?

Tech Off - Where can I find some blogs or video training on doing mutliple windows with WPF?

Scott — Mon, 12 Dec 2011 18:43:52 GMT

@RodAtWork: With the MVVM pattern, your views shouldn't know about each other. Your windows will bind to the same data and update when that data is changed.

Window 1 -> window 1 view model -> data 1 -> window 2 view model -> window 2

With the binding system in WPF, you don't need to do anything except raise a notification that the data has changed (INotifyPropertyChanged interface).

Tech Off - Where can I find some blogs or video training on doing mutliple windows with WPF?

William Kempf — Mon, 12 Dec 2011 19:14:51 GMT

@spivonious is right that views shouldn't be aware of each other. There's several ways to deal with this. One simple solution is like he says, use a shared object. For instance, every WPF application has an Application object and you could share the data off of this (really decoupling things here is still a good idea, and I inject an IApplication interface into my View Models instead of reference Application.Current). Another option is to use an EventAggregator, and I believe MVVM Light has one built in.

Tech Off - Where can I find some blogs or video training on doing mutliple windows with WPF?

RodAtWork — Mon, 12 Dec 2011 20:50:15 GMT

One method is to put all of the data elements into a single file? Really? I've just counted up the number of columns there are in all of the data tables, in this application. There are 428 data columns that are a part of the old application. That's not including all of the lookup tables and their columns, The number will easily approach 600 columns from the various tables, that comprise this application. That would make for one really huge file, if everything is in it! So many columns all in one place, makes it difficult for more than 1 person to work on at a time. I don't know, that just seems wrong, to me, to put that much data in one place.

Tech Off - Where can I find some blogs or video training on doing mutliple windows with WPF?

William Kempf — Mon, 12 Dec 2011 21:02:37 GMT

Wow, did you read something wrong. Firstly, I highly doubt all of those "columns" need to be shared between views. Secondly, being able to access the shared data from one place does NOT mean all of the code lives in a single class/file. Thirdly, this is only ONE of the many solutions available to you, and two were spelled out in this thread.

Tech Off - Where can I find some blogs or video training on doing mutliple windows with WPF?

Scott — Wed, 14 Dec 2011 20:09:34 GMT

1 day ago, RodAtWork wrote
One method is to put all of the data elements into a single file? Really? I've just counted up the number of columns there are in all of the data tables, in this application. There are 428 data columns that are a part of the old application. That's not including all of the lookup tables and their columns, The number will easily approach 600 columns from the various tables, that comprise this application. That would make for one really huge file, if everything is in it! So many columns all in one place, makes it difficult for more than 1 person to work on at a time. I don't know, that just seems wrong, to me, to put that much data in one place.

Who said anything about a single file?

Architect your application so that one instance of the business layer can be accessed from two different viewmodels. If the views are bound to the same instance, then there's no reason to pass data between views.

And remember, even though WPF shines with the MVVM pattern, it is not the only design pattern choice. This particular application may not benefit from separation of the view and the viewmodel.

Tech Off - Where can I find some blogs or video training on doing mutliple windows with WPF?

RodAtWork — Thu, 19 Jan 2012 20:23:25 GMT

Dec 14, 2011 at 1:09 PM, spivonious wrote
*snip*
Who said anything about a single file?
Architect your application so that one instance of the business layer can be accessed from two different viewmodels. If the views are bound to the same instance, then there's no reason to pass data between views.
And remember, even though WPF shines with the MVVM pattern, it is not the only design pattern choice. This particular application may not benefit from separation of the view and the viewmodel.

Good reminder, thank you.

Tech Off - Where can I find some blogs or video training on doing mutliple windows with WPF?

JohnAskew — Tue, 06 Mar 2012 19:09:19 GMT

@RodAtWork: http://channel9.msdn.com/posts/Implementing-an-MVVM-MessageBus-with-XAML

This may be what you want exactly.