CODEWITHSUNDEEP
c#wpfmvvmdatatemplate
NZJames
NZJames

Reputation: 5055

WPF set DataTemplate on Viewmodel class programmatically

I have a listbox in WPF that will contain a list of ResultsViewModel items, however the actual runtime type of these objects could be

all of which extend the base abstract class ResultsViewModel.

Each of these view models should be rendered differently in the ListBox so needs a different DataTemplate. I can do that just with XAML easy enough. The difficulty is that when the viewmodels are either "processing" or when they have failed", I need them to display a DataTemplate for "processing" or "errored" which I can only so far do with Triggers. That however then means I can't use the DataTemplateSelector or a basic XAML style.

The only solution I can think of (not clean I know) is to set the DataTemplate programmatically in the SetResult() method of each viewmodel class, which is what gets called when the processing completes either successfully or with an error. In that DependencyProperty I can look at the return code and then programatically set the DataTemplate depending on the sucess/failure result. The only problem is I cannot figure out how to

  1. Obtain a DataTemplate resource from a ResourceDictionary just using c# code - bearing in mind Im calling all of this from the viewmodel class, not the window code-behind .xaml.cs file so it doesn't have access to the properties of Window

  2. having only a handle to the viewmodel class, somehow obtain a reference to the ListBoxItem that contains it and then programmatically set the DataTemplate on this container.

Can anyone point me in the right direction?

Upvotes: 2

Views: 666

Answers (1)

punker76
punker76

Reputation: 14621

you can take the magic with implicit datatemplates

<ListBox ItemSource={Binding YourResults}>
  <ListBox.Resources>
    <DataTemplate DataType={x:Type CalculateResultsViewModel}>
      <Grid></Grid>
    </DataTemplate>
    <DataTemplate DataType={x:Type ScenarioResultsViewModel}>
      <Grid></Grid>
    </DataTemplate>
    <DataTemplate DataType={x:Type GraphResultsviewModel }>
      <Grid></Grid>
    </DataTemplate>
  </ListBox.Resources>
</ListBox>

for "processing" or "errored" viewmodels you can specify a adorner overlay in all yout datatemplates (ok but you must use the triggers)

hope this helps

Upvotes: 2

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