react / react/react-native

[iOS] SectionList - Weird ListHeaderComponent re-render when no section data

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#34,399 4 comments 1 reaction 0 assignees View on GitHub

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Component: SectionList Needs: Triage :mag: Never gets stale Platform: iOS
Dominant language
C++
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Description

Description

Only on iOS, when using a SectionList ListHeaderComponent, providing sections = [] will cause a weird re-render, whereas if there is any section data, this re-render does not happen.

Basically, is there any reason that the HeaderComponent should be forced to re-render when "sections" changes?

2022-08-12 11 36 42

See Snack below of repro steps.

Version

0.67.2

Output of npx react-native info

System:
OS: macOS 12.5
CPU: (10) arm64 Apple M1 Pro
Memory: 581.61 MB / 32.00 GB
Shell: 5.8.1 - /bin/zsh
Binaries:
Node: 14.18.1 - ~/.nvm/versions/node/v14.18.1/bin/node
Yarn: 1.22.17 - ~/.nvm/versions/node/v14.18.1/bin/yarn
npm: 6.14.15 - ~/.nvm/versions/node/v14.18.1/bin/npm
Watchman: 2022.05.30.00 - /opt/homebrew/bin/watchman
Managers:
CocoaPods: 1.11.3 - /opt/homebrew/bin/pod
SDKs:
iOS SDK:
Platforms: DriverKit 21.4, iOS 15.5, macOS 12.3, tvOS 15.4, watchOS 8.5
Android SDK: Not Found
IDEs:
Android Studio: Not Found
Xcode: 13.4.1/13F100 - /usr/bin/xcodebuild
Languages:
Java: 17.0.1 - /usr/bin/javac
npmPackages:
@react-native-community/cli: Not Found
react: 17.0.2 => 17.0.2
react-native: ^0.67.2 => 0.67.2
react-native-macos: Not Found
npmGlobalPackages:
react-native: Not Found

Steps to reproduce

See Snack below, and follow these steps (need to load on iOS device, doesn't happen in web/android)

  1. Scroll "filter pills" component to it's right-most state
  2. Click "One", notice how the section list data filters to only rows with "One"
  3. Deselect "One"
  4. Click "Seven", notice how the "filter pills" component has jolted all the way back to the left, as there is no data found to filter by
Snack, code example, screenshot, or link to a repository

https://snack.expo.dev/@tyler16cote/section-list-empty-render

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by reproducing the Snack example on an iOS device with SectionList, an empty sections array, and a ListHeaderComponent. Trace the SectionList behavior when sections changes and confirm that the header no longer re-renders or jolts when the list has no data, while preserving the behavior for populated sections.

Written by the indexing model from the issue text.

Assessment

Tech stack
ios, react-native
Domain
mobile
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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