CODEWITHSUNDEEP
windows-phone-7windows-phone-8windows-phone
Lee Denbigh
Lee Denbigh

Reputation: 80

Panorama Control not showing data

I am making a Panorama Windows Phone 8 app. This is the first time I have actually used one in an app.

I am having problems showing the data in runtime. Instead I am only seeing a list:

RuntimeOne RuntimeTwo RuntimeThree etc..

I don't have a clue what has happened, it worked the other day. I am going into the SampleData folder and changing LineOne, LineTwo, LineThree, etc but it's not doing anything when I deploy the app to the Windows Phone Emulator.

Upvotes: 0

Views: 177

Answers (1)

Jim O'Neil
Jim O'Neil

Reputation: 23764

What's happening is that there are two different sets of data, and the DataContext at runtime is different from design time.

  1. The data that you see in design mode ('design one', 'design two') is stored in MainViewModelSampleData.cs, so changing that doesn't affect the runtime experience.

  2. The data at runtime is coming from the LoadData method in MainViewModel.cs

At the top of MainPage.xaml, you'll see

      d:DataContext="{d:DesignData SampleData/MainViewModelSampleData.xaml}"

and the "d" namespace here is a mnemonic for 'design'. If you look at the sample data XAML file, you'll notice it declares a class called MainViewModel with a collection of Items.

At runtime, MainViewModel.cs (specifically the LoadData method) adds items one by one to the Items property of the MainViewModel class, and that class is in turn set to be the runtime DataContext in the constructor of MainPage

The panorama control itself has markup like

            <phone:LongListSelector Margin="0,0,-22,0" ItemsSource="{Binding Items}">

so it's expecting to see a collection called Items on whatever the current DataContext is, and the fact two different data contexts are in play explains what you're seeing.

The data binding magic is incredibly cool and powerful, but sometimes does leave you scratching your head.

Upvotes: 1

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