xamarin/Xamarin.Forms

[Bug] Attached Collection Property return the property for all views and not just the one that is calling

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#9,151 opened on Jan 10, 2020

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a/binding ⛓e/3 :clock3:help wantedinactivet/bug :bug:up-for-grabs

Description

Description

When having Collection like IList as an attached property, GetValue return the value for all views that has this property instead of return just the property related to the view that is calling GetValue.

Steps to Reproduce

  1. Run the sample.
  2. Click on the button that will execute code to get the properties to different views.

Expected Behavior

Method return property related only to itself.

Actual Behavior

view.GetValue return properties to all views that has it.

Basic Information

  • Version with issue: Xamarin.Forms (4.4.0.991265)

Reproduction Link

Sample with Issue

Contributor guide

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.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
C#Xamarin.Forms attached properties
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
45
Research direction
Investigate the attached property implementation in Xamarin.Forms. The issue is that GetValue returns the same collection for all views when it should be per view. Look at how attached properties are stored and retrieved, particularly for IList types. Examine the sample repository at https://github.com/MathewLC/AttachedPropertyIssue for reproduction. Check if there is a known root cause in the Xamarin.Forms source code, e.g., in BindableObject or AttachedCollectionProperty classes.