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This is the first part of a two-part series on working with collections in WCF RIA Services:

• Working with collections in WCF RIA Services – EntitySet and EntityList
• Working with collections in WCF RIA Services – ICollectionView and DomainCollectionView

Introduction

A lot of business applications today are built with WCF RIA Services (which should come as no surprise, as it’s a really powerful, extensible framework).  However, the collection type support could have been better.

Source: The <silver/> method

There has been a lot of debate around what to do with collections of Model objects live under a ViewModel. Consider the situation where a Person has a collection of Nicknames and you have created a PersonViewModel. The debate centers around whether you should expose the Nicknames to binding directly, or if you should create a collection of NicknameViewModels to which binding should occur.

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Kevin Dockx discusses a problem with collection properties being shared with all instances of your controls.

Last week, I was helping out one of our clients with their Silverlight application.  An application which uses custom controls.  One of which contained a collection that seemed to behave as a singleton instead of on an instance level…  I remembered the problems I faced with this before, already thinking we wouldn’t find a solution to keep this collection dynamic.  However, I started searching around again, and lo and behold, it wasn’t long before I found this page on MSDN, describing the exact problem we were facing AND offering a reason and solution. 

The PagedCollectionView class supports the ICollectionView interface that supports a number of features that are really useful for dealing with collections. These include:

• Sorting
• Filtering
• Grouping

Jonathan van de Veen writes about a problem he experienced in his Enterprise Application series that he wanted to post as a single article. He explains how a dependency property is getting accessed sooner than expected thus causing trouble.

I did ran into this while working on the Selector control as mentioned in part #11 of this series, but it's such a general pitfall, I figured it makes sense to put it outside the series.

As you may remember from this article, I placed two datagrids inside a usercontrol to allow users to select items by moving them from one list to another. As many of you already know, one of the features of the DataGrid control is the option to specify your own columns trough the Columns property. I wanted the users of my control to have the same functionality.

So why were collections created in the first place? In essence collections are a storage and network optimization.