xamarin/Xamarin.Forms

The order of 'IsEnabled' and 'Command' should not matter

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#2,758 opened on May 17, 2018

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Description

Description

I have two buttons:

<Button
    Text="Button1"
    Command="{Binding TheCommand}"
    IsEnabled="False" />

<Button
    Text="Button2"
    IsEnabled="False"
    Command="{Binding TheCommand}" />

For some reason, the IsEnabled property is overwritten in Button2 - this enables the button incorrectly.

Button1 is disabled this way, but when I trigger TheCommand.ChangeCanExecute(), the button enables.

Expected Behavior

Both buttons stay disabled.

The matrix of this should be an && operation:

TheCommand.CanExecute() IsEnabled Final State
True True Enabled
True False Disabled
False True Disabled
False False Disabled

Actual Behavior

The button with the command applied later overwrites the enabled state.

Basic Information

  • Version with issue: 2.5.x and 3.0
  • Last known good version: unsure
  • IDE: VS2017
  • Platform Target Frameworks: all

Contributor guide

Research direction
Investigate the order dependency between IsEnabled and Command in Xamarin.Forms Button. Trace the property setting logic to understand why setting Command after IsEnabled overwrites the disabled state.
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
Xamarin.FormsC#MVVM
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
30