fix(workflow): fetch user failed when workflow run in parallel mode (#20321)

Signed-off-by: -LAN- <laipz8200@outlook.com>

api/core/workflow/graph_engine/graph_engine.py

@@ -9,7 +9,7 @@ from copy import copy, deepcopy
 from datetime import UTC, datetime
 from typing import Any, Optional, cast
 
-from flask import Flask, current_app
+from flask import Flask, current_app, has_request_context
 
 from configs import dify_config
 from core.app.apps.base_app_queue_manager import GenerateTaskStoppedError
@@ -540,8 +540,21 @@ class GraphEngine:
         for var, val in context.items():
             var.set(val)
 
+        # FIXME(-LAN-): Save current user before entering new app context
+        from flask import g
+
+        saved_user = None
+        if has_request_context() and hasattr(g, "_login_user"):
+            saved_user = g._login_user
+
         with flask_app.app_context():
             try:
+                # Restore user in new app context
+                if saved_user is not None:
+                    from flask import g
+
+                    g._login_user = saved_user
+
                 q.put(
                     ParallelBranchRunStartedEvent(
                         parallel_id=parallel_id,