Working with Drupal Patch Files

December 18, 2017 - 16:18

A patch is a small file which shows what was changed in a repository. It shows the new changes in an existing file, details of the new files in the current directory, file deletion details etc. A patch file can be pushed to the git repository so that it is useful in the future for updating the changes in the corresponding file.

For creating a patch file in your current git repository, make changes in your files. Now open the terminal.

For unstaged changes, type the following command,

git diff > new-changes.patch

For staged changes, you have to use git diff --cached. That is,

git diff --cached > new-changes.patch

To apply the patch, use:

git apply -v new-changes.patch

Note that, if the changes is already there when applying your patch, error message will be shown.

In Drupal.org, you can contribute patches to the existing core or contributed modules. For this,

  • First clone the latest version of Drupal (if it is a contributed module clone the latest code from its version control)
  • You have to create the issue with necessary issue summary in Drupal.org based on the fix
  • After making the changes, create a patch file based on the issue number as,
    git diff > [issue-description]-[issue-number]-[comment-number].patch
  • Update the issue with necessary comment and patch file
  • Make it's status as 'Needs Review'
  • If you want to test the patch file, add it to the queue by clicking the 'Add test' link shown below of the updated patch file

We can create and add inter diff for adding new modification for an existing patch file in an issue in Drupal.org, if the changes are not in the latest version of the module. For this,

  • Apply the existing patch to the latest version of module
  • Add your changes to the module
  • Create a new patch from git diff using git diff > [issue-description]-[issue-number]-[comment-number].patch
  • Create an inter diff from the old and new patches as:
    interdiff old-file.patch new-file.patch > interdiff-[issue_id]-[old_comment_number]-[new_comment_number].txt
  • Upload the newly created patch and the inter diff to the created issue in Drupal.org.

An interdiff file tells you what new changes are there with the existing patch and newly created patch. It provides the information of the changes in patch files. So we can make the file as test free using 'do not test' option in the issues itself. So for interdiff to be ignored by the testbot, we can name the interdiff file as:

interdiff-[issue_id]-[old_comment_number]-[new_comment_number]-do-not-test.diff

Hope this information helps in your patch creation.

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