修复.to_dict()功能

Change-Id: I6e42cb9ecc915bc713e547b05f8bd3c2b53034c8
diff --git a/API/API-TRM/TRM/Back/app/models/users.py b/API/API-TRM/TRM/Back/app/models/users.py
index 2cd9871..0505e86 100644
--- a/API/API-TRM/TRM/Back/app/models/users.py
+++ b/API/API-TRM/TRM/Back/app/models/users.py
@@ -8,7 +8,18 @@
 class User(Base):
     __tablename__ = 'users'
 
-
+    def to_dict(self):
+        return {
+            'id': self.id,
+            'username': self.username if self.username else None,
+            'email': self.email if self.email else None,
+            'avatar': self.avatar if self.avatar else None,
+            'role': self.role if self.role else None,
+            'bio': self.bio if self.bio else None,
+            'status': self.status if self.status else None,
+            'created_at': self.created_at.isoformat() if self.created_at else None,
+            'updated_at': self.updated_at.isoformat() if self.updated_at else None
+        }