xamarin/Xamarin.Forms

ListView's GroupHeaderTemplate do not work with DataTemplateSelector on Android

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#3,407 opened on Jul 26, 2018

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Description

version Xamarin.Forms.3.1.0.637273 and Xamarin.Forms 3.1.0.583944

I want to use the DataTemplateSelector for the GroupHeaderTemplate.

<ListView Grid.Row="1" ItemsSource="{Binding PickerGroups}" IsGroupingEnabled="True" ItemTemplate="{StaticResource PickerDataTemplateSelector}"
                  GroupHeaderTemplate="{StaticResource PickerDataTemplateSelector}"  CachingStrategy="RecycleElementAndDataTemplate">
</ListView>

I get here such a crash:

ListProxy.get_Item (System.Int32 index)
D:\a\1\s\Xamarin.Forms.Core\ListProxy.cs - line 127
System.ArgumentOutOfRangeException: Specified argument was out of the range of valid values. Parameter name: index

1 ListProxy.get_Item (System.Int32 index) D:\a\1\s\Xamarin.Forms.Core\ListProxy.cs:127
2 IList.get_Item (System.Int32 index) D:\a\1\s\Xamarin.Forms.Core\ListProxy.cs:444
3 ListViewAdapter.GetItemViewType (System.Int32 position) D:\a\1\s\Xamarin.Forms.Platform.Android\Renderers\ListViewAdapter.cs:172
4 BaseAdapter.n_GetItemViewType_I (System.IntPtr jnienv, System.IntPtr native__this, System.Int32 position)
5 (wrapper dynamic-method) System.Object.cbacde75-f4e8-4fe2-bec7-81edead3c9fe(intptr,intptr,int)

Contributor guide

Research direction
Examine ListViewAdapter.GetItemViewType in Xamarin.Forms.Platform.Android to understand how it handles grouped data with a DataTemplateSelector. The crash occurs because the adapter tries to access an invalid index when the group header uses a DataTemplateSelector. Check if the issue is related to the recycling mechanism and ensure the header view type is correctly determined.
Tech stack
csharp
Domain
mobile
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
Half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
C#
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40