items collection must be empty before using itemssource – WCF or Silverlight

If you received an error “items collection must be empty before using” you might have done this, in xaml you have:


<ListBox Height=”299″ HorizontalAlignment=”Left” Name=”listBox1″ VerticalAlignment=”Top” Width=”469″>

  <Image Source=”{Binding imgField}”>



and at the code behind you have:


public MainWindow()



  MyImageEntities context = newMyImageEntities();

  var mi = from i in context.MyImages select i;

  listBox1.ItemsSource = mi;



You need to change the xaml to something like:


<ListBox Height=”299″ HorizontalAlignment=”Left” Name=”listBox1″ VerticalAlignment=”Top” Width=”469″ >





          <ColumnDefinition Width=”Auto”></ColumnDefinition>


        <Image Source=”{Binding imgField}” Grid.Column=”0″ Width=”50″ Height=”50″ Stretch=”UniformToFill” Margin=”3″>            







The code behind remain the same. This should work.


About chanmingman

Since March 2011 Microsoft Live Spaces migrated to Wordpress ( till now, I have is over 1 million viewers. This blog is about more than 50% telling you how to resolve error messages, especial for Microsoft products. The blog also has a lot of guidance teaching you how to get stated certain Microsoft technologies. The blog also uses as a help to keep my memory. The blog is never meant to give people consulting services or silver bullet solutions. It is a contribution to the community. Thanks for your support over the years. Ming Man is Microsoft MVP since year 2006. He is a software development manager for a multinational company. With 25 years of experience in the IT field, he has developed system using Clipper, COBOL, VB5, VB6, VB.NET, Java and C #. He has been using Visual Studio (.NET) since the Beta back in year 2000. He and the team have developed many projects using .NET platform such as SCM, and HR based applications. He is familiar with the N-Tier design of business application and is also an expert with database experience in MS SQL, Oracle and AS 400.
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