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[Bug] Picker selection cleared when used in CollectionView and scrolled out of view #14330

Open BenBtg opened 3 years ago

BenBtg commented 3 years ago

Description

See this sample app which repros the issue Issue Repro

Steps to Reproduce

  1. Launch app and populated first item in list ensuring to select the Picker entries
  2. Add about 5 more items by clicking the add button
  3. Scoll list back to top.

Expected Behavior

All entries in the item maintain their value including the pickers

Actual Behavior

Pickers are cleared

Basic Information

Environment

<!-Microsoft Visual Studio Enterprise 2019 Preview Version 16.11.0 Preview 1.0 VisualStudio.16.Preview/16.11.0-pre.1.0+31320.298 Microsoft .NET Framework Version 4.8.04084

Installed Version: Enterprise

Visual C++ 2019 00435-60000-00000-AA337 Microsoft Visual C++ 2019

ASP.NET and Web Tools 2019 16.11.40.5765 ASP.NET and Web Tools 2019

ASP.NET Core Blazor Language Services 16.0.19307.2

ASP.NET Web Frameworks and Tools 2019 16.11.40.5765 For additional information, visit https://www.asp.net/

Azure App Service Tools v3.0.0 16.11.40.5765 Azure App Service Tools v3.0.0

C# Tools 3.11.0-1.21264.4+0ed7600c68d3007a3812d77494fa53d8fb097a31 C# components used in the IDE. Depending on your project type and settings, a different version of the compiler may be used.

Common Azure Tools 1.10 Provides common services for use by Azure Mobile Services and Microsoft Azure Tools.

Extensibility Message Bus 1.2.6 (master@34d6af2) Provides common messaging-based MEF services for loosely coupled Visual Studio extension components communication and integration.

IntelliCode Extension 1.0 IntelliCode Visual Studio Extension Detailed Info

Microsoft Continuous Delivery Tools for Visual Studio 0.4 Simplifying the configuration of Azure DevOps pipelines from within the Visual Studio IDE.

Microsoft JVM Debugger 1.0 Provides support for connecting the Visual Studio debugger to JDWP compatible Java Virtual Machines

Microsoft Library Manager 2.1.113+g422d40002e.RR Install client-side libraries easily to any web project

Microsoft MI-Based Debugger 1.0 Provides support for connecting Visual Studio to MI compatible debuggers

Microsoft Visual C++ Wizards 1.0 Microsoft Visual C++ Wizards

Microsoft Visual Studio Tools for Containers 1.2 Develop, run, validate your ASP.NET Core applications in the target environment. F5 your application directly into a container with debugging, or CTRL + F5 to edit & refresh your app without having to rebuild the container.

Microsoft Visual Studio VC Package 1.0 Microsoft Visual Studio VC Package

Mono Debugging for Visual Studio 16.10.15 (552afdf) Support for debugging Mono processes with Visual Studio.

NuGet Package Manager 5.11.0 NuGet Package Manager in Visual Studio. For more information about NuGet, visit https://docs.nuget.org/

ProjectServicesPackage Extension 1.0 ProjectServicesPackage Visual Studio Extension Detailed Info

Razor (ASP.NET Core) 16.1.0.2122504+13c05c96ea6bdbe550bd88b0bf6cdddf8cde1725 Provides languages services for ASP.NET Core Razor.

SQL Server Data Tools 16.0.62105.11120 Microsoft SQL Server Data Tools

TypeScript Tools 16.0.30429.2002 TypeScript Tools for Microsoft Visual Studio

Visual Basic Tools 3.11.0-1.21264.4+0ed7600c68d3007a3812d77494fa53d8fb097a31 Visual Basic components used in the IDE. Depending on your project type and settings, a different version of the compiler may be used.

Visual F# Tools 16.10.0-beta.21262.7+1b23bbeda88ea3cb9be9af777f4c99fa8663df81 Microsoft Visual F# Tools

Visual Studio Code Debug Adapter Host Package 1.0 Interop layer for hosting Visual Studio Code debug adapters in Visual Studio

Visual Studio Container Tools Extensions 1.0 View, manage, and diagnose containers within Visual Studio.

Visual Studio Tools for Containers 1.0 Visual Studio Tools for Containers

VisualStudio.DeviceLog 1.0 Information about my package

VisualStudio.Foo 1.0 Information about my package

VisualStudio.Mac 1.0 Mac Extension for Visual Studio

Xamarin 16.11.000.149 (d16-11@cb8efbe) Visual Studio extension to enable development for Xamarin.iOS and Xamarin.Android.

Xamarin Designer 16.10.0.115 (remotes/origin/c750fbf1bde3c720d077f51640fe197c6dac7cbe@c750fbf1b) Visual Studio extension to enable Xamarin Designer tools in Visual Studio.

Xamarin Templates 16.10.5 (355b57a) Templates for building iOS, Android, and Windows apps with Xamarin and Xamarin.Forms.

Xamarin.Android SDK 11.3.99.31 (main/92efdcc) Xamarin.Android Reference Assemblies and MSBuild support. Mono: b4a3858 Java.Interop: xamarin/java.interop/main@12e670a ProGuard: Guardsquare/proguard/v7.0.1@912d149 SQLite: xamarin/sqlite/3.35.4@85460d3 Xamarin.Android Tools: xamarin/xamarin-android-tools/main@683f375

Xamarin.iOS and Xamarin.Mac SDK 14.20.0.1 (fe0e2c518) Xamarin.iOS and Xamarin.Mac Reference Assemblies and MSBuild support.

Build Logs

Screenshots

Reproduction Link

Workaround

Nathan-Coit-FP commented 2 years ago

Ran into the same issue. Looks like it only happens when both ItemsSource and SelectedItem use binding. When the Picker is out of view, the SelectItem_Changed event is being fired with null.

Maybe because the ItemsSource is being removed from the Picker first?

Workaround was to only call SetValue on the bindable SelectedItem property if value != null and the ItemsSource isn't empty.