make a media api, encapsulate the original S3 bucket address

there are 3 parts, from back to head, url inside the bucket -> url of backend media api -> backend domain, only the last part is spliced by frontend, the other two parts are spliced with sqlalchemy

app/graphql/types.py

@@ -4,15 +4,19 @@ from datetime import datetime
 from strawberry.types import Info
 
 from app.utils.format import get_image_url
+from app.models.user import User
 
 @strawberry.type
 class UserType:
     id: str
     email: str
     name: str
-    avatar: str
     handle: Optional[str]
     
+    @strawberry.field
+    def avatar(self, root: User) -> Optional[str]:
+        return root.avatar_url
+    
     # 互动统计字段
     following_count: int
     follower_count: int