PR Description Updater

A GitHub Action that updates pull request descriptions using regex patterns for content matching and replacement. This action allows you to dynamically update PR descriptions with content from files or direct text input, supporting various regex matching strategies.

Features

• Regex-based content replacement: Replace specific sections of PR descriptions using regex patterns
• Content from files or direct input: Use file contents or direct text as the new content
• Flexible matching options: Support for case-insensitive, global, multiline, and other regex flags
• Conditional updates: Only update PR descriptions when specific patterns are found
• Content extraction: Extract specific parts from content using regex before updating
• Automatic PR detection: Works with PR events or commit-based PR lookup

Inputs

Input	Description	Required	Default
content	Content to use for PR description update or file path if contentIsFilePath is true	Yes	-
contentIsFilePath	Whether content input is a file path (true) or direct content (false)	No	false
contentRegex	Regex pattern to extract specific content from the content input	No	""
contentRegexFlags	Regex flags for contentRegex (e.g., g, i, m, s)	No	""
regex	Regex pattern to match in PR body for replacement	No	---.*
regexFlags	Regex flags for regex pattern (e.g., g, i, m, s)	No	""
appendContentOnMatchOnly	Only update PR body if regex matches (true) or always update (false)	No	false
token	GitHub token for API access	Yes	-

Usage Examples

Basic Usage - Replace Default Pattern

name: Update PR Description
on:
  pull_request:
    types: [opened, synchronize]

jobs:
  update-description:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      - name: Update PR Description
        uses: step-security/update-pr-description@v1
        with:
          content: |
            ## Summary
            This PR implements new features and bug fixes.

            ## Changes
            - Added new functionality
            - Fixed existing issues
          token: ${{ secrets.GITHUB_TOKEN }}

Advanced Usage - File-based Content with Regex

name: Update PR Description from File
on:
  pull_request:
    types: [opened, synchronize]

jobs:
  update-description:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      - name: Update PR Description
        uses: step-security/update-pr-description@v1
        with:
          content: .github/pr-template.md
          contentIsFilePath: true
          regex: '## Description.*?(?=##|$)'
          regexFlags: 's'
          appendContentOnMatchOnly: true
          token: ${{ secrets.GITHUB_TOKEN }}

Extract Content with Regex

name: Extract and Update PR Description
on:
  pull_request:
    types: [opened, synchronize]

jobs:
  update-description:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      - name: Update PR Description
        uses: step-security/update-pr-description@v1
        with:
          content: |
            <!-- START_EXTRACT -->
            ## Important Changes
            This section will be extracted and used.
            <!-- END_EXTRACT -->
            This content will be ignored.
          contentRegex: '<!-- START_EXTRACT -->(.*?)<!-- END_EXTRACT -->'
          contentRegexFlags: 's'
          regex: '---.*'
          token: ${{ secrets.GITHUB_TOKEN }}

Case-Insensitive Global Replacement

name: Global Case-Insensitive Update
on:
  pull_request:
    types: [opened, synchronize]

jobs:
  update-description:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      - name: Update PR Description
        uses: step-security/update-pr-description@v1
        with:
          content: '**UPDATED**'
          regex: 'todo'
          regexFlags: 'gi'
          token: ${{ secrets.GITHUB_TOKEN }}

Conditional Update Only on Match

name: Conditional PR Description Update
on:
  pull_request:
    types: [opened, synchronize]

jobs:
  update-description:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      - name: Update PR Description
        uses: step-security/update-pr-description@v1
        with:
          content: |
            ## Automated Update
            This PR has been automatically updated.
          regex: '\[AUTO-UPDATE\]'
          appendContentOnMatchOnly: true
          token: ${{ secrets.GITHUB_TOKEN }}

How It Works

1. PR Detection: The action first identifies the pull request number from the event context or by looking up PRs associated with the current commit
2. Content Preparation: Loads content from direct input or file, then optionally extracts specific parts using contentRegex
3. Pattern Matching: Tests the current PR description against the specified regex pattern
4. Content Update: Based on the match result and appendContentOnMatchOnly setting:
   • If pattern matches: Replaces the matched section with new content
   • If no match and appendContentOnMatchOnly is false: Appends content to existing description or sets as new description if empty
   • If no match and appendContentOnMatchOnly is true: Skips the update

Regex Flags

Common regex flags you can use:

• g - Global: Replace all matches, not just the first one
• i - Case-insensitive: Ignore case when matching
• m - Multiline: ^ and $ match start/end of lines
• s - Dotall: . matches newline characters

License

This project is licensed under the MIT License.