GitLab MCP Code Review

Instructions

Fetch a GitLab merge request and its contents.

IMPORTANT: You MUST call fetch_code_review_rules BEFORE using this tool to understand 
the team's code review standards and guidelines.

Args:
    project_id: The GitLab project ID or URL-encoded path
    merge_request_iid: The merge request IID (project-specific ID)
Returns:
    XML string containing the merge request information

Implementation Reference

• server.py:211-320 (handler)

  The handler function decorated with @mcp.tool() that implements the core logic for fetching and processing GitLab merge request data, filtering changes, collecting commits and discussions, and formatting the output as XML.

  @mcp.tool()
  def fetch_merge_request(ctx: Context, project_id: str, merge_request_iid: str):
      """
      Fetch a GitLab merge request and its contents.
      
      IMPORTANT: You MUST call fetch_code_review_rules BEFORE using this tool to understand 
      the team's code review standards and guidelines.
      
      Args:
          project_id: The GitLab project ID or URL-encoded path
          merge_request_iid: The merge request IID (project-specific ID)
      Returns:
          XML string containing the merge request information
      """
      gl = ctx.request_context.lifespan_context
      project = gl.projects.get(project_id)
      mr = project.mergerequests.get(merge_request_iid)
  
      # 精简 merge_request 信息
      mr_data = mr.asdict()
      slim_mr = {
          "id": mr_data.get("id"),
          "iid": mr_data.get("iid"),
          "project_id": mr_data.get("project_id"),
          "title": mr_data.get("title"),
          "description": mr_data.get("description"),
          "state": mr_data.get("state"),
          "author": mr_data.get("author", {}).get("name"),
          "source_branch": mr_data.get("source_branch"),
          "target_branch": mr_data.get("target_branch"),
      }
  
      # 获取并过滤 changes
      original_changes_data = mr.changes()
      all_changes = original_changes_data.get("changes", [])
  
      exclude_patterns = config.get("exclude_patterns", [])
  
      filtered_changes_list = []
      for change in all_changes:
          file_path = change.get("new_path")
          if not is_path_excluded(file_path, exclude_patterns):
              slim_change = {
                  "new_path": change.get("new_path"),
                  "old_path": change.get("old_path"),
                  "new_file": change.get("new_file"),
                  "renamed_file": change.get("renamed_file"),
                  "deleted_file": change.get("deleted_file"),
                  "diff": change.get("diff")
              }
              filtered_changes_list.append(slim_change)
      
      # 创建一个只包含必要字段的精简版 changes 对象
      slim_changes_obj = {
          "diff_refs": original_changes_data.get("diff_refs"),
          "changes": filtered_changes_list
      }
  
      # 精简 commits
      commits = [
          {
              "id": c.id,
              "short_id": c.short_id,
              "title": c.title,
              "author_name": c.author_name,
          }
          for c in mr.commits(all=True)
      ]
  
      def slim_note(note):
          if not isinstance(note, dict):
              note = note.asdict()
          author = note.get("author", {})
          return {
              "id": note.get("id"),
              "type": note.get("type"),
              "body": note.get("body"),
              "system": note.get("system"),
              "author": author.get("name"),
              "position": note.get("position", {}),
          }
  
      # 精简 discussions 和其下的 notes
      all_discussions = mr.discussions.list(all=True)
  
      discussions = []
      for d in all_discussions:
          # d.attributes['notes'] 包含了该 discussion 下的所有 note 信息
          slim_notes_list = [slim_note(n) for n in d.attributes.get('notes', [])]
          discussions.append({
              "id": d.id,
              "individual_note": d.individual_note,
              "notes": slim_notes_list
          })
  
      # 构建最终的数据结构
      result_data = {
          "merge_request": slim_mr,
          "changes": slim_changes_obj,
          "commits": commits,
          "discussions": discussions,
      }
      
      # 转换为XML并返回
      xml_parts = ['<?xml version="1.0" encoding="utf-8"?>\n<merge_request_data>\n']
      for key, value in result_data.items():
          xml_parts.append(dict_to_xml_string(value, key, 1))
      xml_parts.append('</merge_request_data>\n')
      
      return "".join(xml_parts)

• server.py:173-209 (helper)

  Helper function used by fetch_merge_request to recursively convert the merge request data dictionary into an XML-formatted string.

  def dict_to_xml_string(data: Any, tag: str = "item", indent: int = 0) -> str:
      """
      Convert a dictionary or list to XML string format without escaping any characters.
      This output is intended for AI consumption, not for XML parser.
      
      Args:
          data: The data to convert (dict, list, or primitive type)
          tag: The tag name for the current element
          indent: Current indentation level
      Returns:
          The XML string
      """
      indent_str = "  " * indent
      result = []
      
      if isinstance(data, dict):
          result.append(f"{indent_str}<{tag}>\n")
          for key, value in data.items():
              if value is not None:
                  result.append(dict_to_xml_string(value, str(key), indent + 1))
          result.append(f"{indent_str}</{tag}>\n")
      elif isinstance(data, list):
          result.append(f"{indent_str}<{tag}>\n")
          for item in data:
              result.append(dict_to_xml_string(item, "item", indent + 1))
          result.append(f"{indent_str}</{tag}>\n")
      else:
          # Leaf node with text content - no escaping
          if data is None:
              text = ""
          elif isinstance(data, bool):
              text = "true" if data else "false"
          else:
              text = str(data)
          result.append(f"{indent_str}<{tag}>{text}</{tag}>\n")
      
      return "".join(result)

• server.py:66-74 (helper)

  Helper function used in fetch_merge_request to filter out excluded file paths from the merge request changes based on config patterns.

  def is_path_excluded(file_path: str, patterns: List[str]) -> bool:
      """Check if a file path matches any of the exclusion patterns."""
      for pattern in patterns:
          if pattern.endswith('/'):
              if file_path.startswith(pattern) or f"/{pattern}" in file_path:
                  return True
          elif fnmatch.fnmatch(file_path, pattern):
              return True
      return False