Thursday, July 3, 2014

Binding Viewmodel property to tabitem header in MVVm pattern

Its been a while since I started a WPF project from scratch. I was mainly into the architectural side of application rather than UI side. Today I got an opportunity to start one app. It is supposed to be simple WPF application where the screens are arranged in hierarchical tabs.

The application is supposed to be a temporary application which will be used to test an algorithm developed by the business before its getting integrated into the actual application. So thought of not following the MVVm pattern as its supposed to be developed from our offshore in less amount of time. But one discussion with my lead architect changed my decision. If we are doing something we should do it right. We don't know whether the client will get rid of the application if it feels too good for them. Finally decided to go with MVVm.

The initial decision I had to take about the MVVm infrastructure. Earlier when I used to start the project I take my own RelayCommand,ViewmodelBase classes. That was the beginning time of WPF. But this time I decided to use a good library on the assumption that the MVVm framework must be matured by now. It ends up in using MVVM Light. Its a nice library which we can get from nuget.

Then started thinking about the UI structure where the tabs needs to be shown in hierarchical way. Its nothing but there will be one parent level tab control and in every tab page there will be one more tab control. I created the view models and bound to the view. Each high level view model have ChildVMs collection. In the MainPage.xaml UI I was able to bound to the ChildVMs property and they showed up as each and every viewmodel was associated with data template.

        <DataTemplate DataType="{x:Type vms:ChildViewmodel_1}">

But I faced one problem. I could see that the tab headers are also showing the same control which is inside the tab page. Ideally I need to edit the tab header template and bind to the header property in the viewmodel. But I could see one more way which is just a data template for the tab item.

        <TabControl ItemsSource="{Binding ChildVMs}">
                    <TextBlock Text="{Binding Header}" />

Happy coding

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