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Peter Knego
Peter Knego

Reputation: 80330

Jgit: how to show changed files in merge commit

I'd like to use jgit to get a list of files that were changed in a merge commit, similar to what git show --name-only does in git.

There are plenty of examples on how to get changed files for normal commits with one parent, but they do not work for merge commits with multiple parents.

Upvotes: 3

Views: 965

Answers (1)

Rüdiger Herrmann
Rüdiger Herrmann

Reputation: 20985

From my understanding you would simply need to combine the diffs of the parents of the merge commit with their respective parents.

The snippet below creates two commits with each one file added (main.txt and side.txt), the merge commit is then diffed as described above

public void diffMerge() throws Exception {
  RevCommit baseCommit = commitChanges();
  Ref sideBranch = git.branchCreate().setName( "side" ).call();
  File mainFile = new File( git.getRepository().getWorkTree(), "main.txt" );
  mainFile.createNewFile();
  RevCommit mainCommit = commitChanges();
  git.checkout().setName( sideBranch.getName() ).call();
  File sideFile = new File( git.getRepository().getWorkTree(), "side.txt" );
  sideFile.createNewFile();
  RevCommit sideCommit = commitChanges();
  git.checkout().setName( "refs/heads/master" ).call();
  ObjectId mergeCommitId = git.merge().include( sideCommit ).call().getNewHead();

  DiffFormatter diffFormatter = new DiffFormatter( NullOutputStream.INSTANCE );
  diffFormatter.setRepository( git.getRepository() );
  RevCommit mergeCommit = parseCommit( mergeCommitId );
  List<DiffEntry> mainEntries = diffFormatter.scan( parseCommit( mergeCommit.getParent( 0 ) ).getParent( 0 ), mergeCommit.getParent( 0 ) );
  List<DiffEntry> sideEntries = diffFormatter.scan( parseCommit( mergeCommit.getParent( 1 ) ).getParent( 0 ), mergeCommit.getParent( 1 ) );
  diffFormatter.close();

  mainEntries.forEach( entry -> System.out.println( entry.getNewPath() ) );
  sideEntries.forEach( entry -> System.out.println( entry.getNewPath() ) );
}

private RevCommit parseCommit( ObjectId commitId ) throws IOException {
  try( RevWalk revWalk = new RevWalk( git.getRepository() ) ) {
    return revWalk.parseCommit( commitId );
  }
}

private RevCommit commitChanges() throws GitAPIException {
  git.add().addFilepattern( "." ).call();
  return git.commit().setMessage( "commit message" ).call();
}

Note that the code blindly assumes the the parents of the merge commits aren't merges themselves.

Upvotes: 1

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