debian-mirror-gitlab/app/controllers/concerns/diff_for_path.rb

module DiffForPath
  extend ActiveSupport::Concern

  def render_diff_for_path(diffs)
    diff_file = diffs.diff_files.find do |diff|
      diff.file_identifier == params[:file_identifier]
    end

    return render_404 unless diff_file

    render json: { html: view_to_html_string('projects/diffs/_content', diff_file: diff_file) }
  end
end