Merge Request Thread via API

DevSecOps
1

I’d like to use the Merge Request Discussions API to add a comment referencing a specific line of code on the branched side of the diff.

I’m using the python wrapper for the API, and my code looks something like:

file_to_comment = 'foo.py'
line_to_comment = 42

merge_request.discussions.create({
  'body': 'a comment',
  'position': {
    'base_sha': merge_request.diff_refs['base_sha'],
    'start_sha': merge_request.diff_refs['start_sha'],
    'head_sha': merge_request.diff_refs['head_sha'],
    'position': text,
    'new_path': file_to_comment,
    'new_line': line_to_comment,
    'old_path': file_to_comment,
    'old_line': line_to_comment,
  }
})

Depending on the situation, I’ll get an error response of:

line_code can’t be blank, must be a valid line code.

My understanding is that the old_path / old_line must match what gitlab computed as the values of that line on the left hand side of the diff. However, it’s unclear how I could even compute this given the APIs available in the Gitlab API.

Has anyone solved this or have ideas on how to approach it?