CSV Editor

Instructions

Implementation Reference

• src/csv_editor/tools/transformations.py:171-216 (handler)

  Core handler function that performs column selection on the session's pandas DataFrame, including validation, operation recording, and response generation.

  async def select_columns(
      session_id: str, 
      columns: List[str], 
      ctx: Context = None
  ) -> Dict[str, Any]:
      """
      Select specific columns from the dataframe.
      
      Args:
          session_id: Session identifier
          columns: List of column names to keep
          ctx: FastMCP context
          
      Returns:
          Dict with success status and selected columns
      """
      try:
          manager = get_session_manager()
          session = manager.get_session(session_id)
          
          if not session or session.df is None:
              return {"success": False, "error": "Invalid session or no data loaded"}
          
          df = session.df
          
          # Validate columns exist
          missing_cols = [col for col in columns if col not in df.columns]
          if missing_cols:
              return {"success": False, "error": f"Columns not found: {missing_cols}"}
          
          session.df = df[columns].copy()
          session.record_operation(OperationType.SELECT, {
              "columns": columns,
              "columns_before": df.columns.tolist(),
              "columns_after": columns
          })
          
          return {
              "success": True,
              "selected_columns": columns,
              "columns_removed": [col for col in df.columns if col not in columns]
          }
          
      except Exception as e:
          logger.error(f"Error selecting columns: {str(e)}")
          return {"success": False, "error": str(e)}

• src/csv_editor/server.py:220-227 (registration)

  Registers the 'select_columns' tool using the FastMCP @mcp.tool decorator, delegating execution to the imported handler function.

  @mcp.tool
  async def select_columns(
      session_id: str,
      columns: List[str],
      ctx: Context = None
  ) -> Dict[str, Any]:
      """Select specific columns from the dataframe."""
      return await _select_columns(session_id, columns, ctx)