自动更新最后更新日期 | Fern Documentation

您可以使用 GitHub Action 在拉取请求中修改 MDX 文件时自动更新 last-updated 前置属性。这样可以让您的文档”最后更新”时间戳保持准确，无需手动更新。

设置工作流

将此 GitHub Action 工作流添加到您的文档仓库。

当打开或更新拉取请求时，工作流会检测哪些 MDX 文件发生了更改，在其前置属性中更新或添加带有当前日期的 last-updated 字段，并将更改提交回 PR 分支。

日期格式为”月日, 年”（例如，“December 11, 2025”）。您可以通过修改工作流中的 date 命令来自定义格式。

.github/workflows/update-last-updated.yml

name: Update last updated date
# Trigger this workflow when PRs are opened or updated
on:
  pull_request:
    types: [opened, synchronize]
    branches:
      - main  # Adjust to match your main branch name
jobs:
  update-last-updated:
    runs-on: ubuntu-latest
    permissions:
      contents: write         # Required to commit changes
      pull-requests: write    # Required to update the PR
    steps:
      # Step 1: Check out the PR branch
      - name: Checkout repository
        uses: actions/checkout@v4
        with:
          ref: ${{ github.head_ref }}  # Check out the PR's source branch
          fetch-depth: 0
          token: ${{ secrets.GITHUB_TOKEN }}
      # Step 2: Identify which MDX files changed in this PR
      - name: Get changed MDX files
        id: changed-files
        uses: tj-actions/changed-files@v45
        with:
          files: |
            **/*.mdx  # Only track changes to .mdx files
      # Step 3: Update the last-updated field in each changed MDX file
      - name: Update last-updated frontmatter
        if: steps.changed-files.outputs.any_changed == 'true'
        run: |
          # Generate current date in "Month Day, Year" format (e.g., "December 11, 2025")
          # Modify the date format here if you prefer a different style
          CURRENT_DATE=$(date +"%B %-d, %Y")
          echo "Current date: $CURRENT_DATE"
          # Process each changed MDX file
          for file in ${{ steps.changed-files.outputs.all_changed_files }}; do
            echo "Processing: $file"
            # Skip if file was deleted or doesn't exist
            if [ ! -f "$file" ]; then
              echo "File not found, skipping: $file"
              continue
            fi
            # Check if file has frontmatter (must start with ---)
            if ! head -1 "$file" | grep -q "^---"; then
              echo "No frontmatter found, skipping: $file"
              continue
            # If file already has a last-updated field, update it
            elif grep -q "^last-updated:" "$file"; then
              echo "Updating existing last-updated field"
              sed -i "s/^last-updated:.*$/last-updated: $CURRENT_DATE/" "$file"
            # If file has frontmatter but no last-updated field, add it
            else
              echo "Adding last-updated field to existing frontmatter"
              # This awk command inserts the last-updated field just before the closing ---
              awk -v date="$CURRENT_DATE" '
                BEGIN { in_frontmatter=0; added=0 }
                NR==1 && /^---$/ { in_frontmatter=1; print; next }
                in_frontmatter && /^---$/ && !added { print "last-updated: " date; added=1; print; in_frontmatter=0; next }
                { print }
              ' "$file" > "${file}.tmp" && mv "${file}.tmp" "$file"
            fi
          done
      # Step 4: Commit and push the updated files back to the PR
      - name: Commit changes
        if: steps.changed-files.outputs.any_changed == 'true'
        run: |
          git config --local user.email "github-actions[bot]@users.noreply.github.com"
          git config --local user.name "github-actions[bot]"
          git add -A
          # Only commit if there are actual changes
          if git diff --staged --quiet; then
            echo "No changes to commit"
          else
            git commit -m "chore: update last-updated date in MDX files"
            git push
          fi