Avoid Pydantic serializer warnings for Chat

backend/app/models/chat.py

@@ -2,14 +2,14 @@
 from uuid import UUID
 from typing import Optional, Dict
 from pydantic import BaseModel
+from sqlalchemy.types import TypeDecorator, Integer
 from datetime import datetime
 
 from sqlmodel import (
     Field,
     Column,
     DateTime,
     JSON,
-    SmallInteger,
     Relationship as SQLRelationship,
 )
 
@@ -20,6 +20,31 @@ class ChatVisibility(int, enum.Enum):
     PRIVATE = 0
     PUBLIC = 1
 
+# Avoid Pydantic serializer warnings:
+# When fetching values from the database, SQLAlchemy provides raw integers (0 or 1), 
+# which leads to warnings during serialization because Pydantic requires the ChatVisibility enum type.
+
+# automatically handle the conversion between int and enum types
+class IntEnumType(TypeDecorator):
+    impl = Integer
+
+    def __init__(self, enum_class, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        self.enum_class = enum_class
+
+    def process_bind_param(self, value, dialect):
+        # enum -> int
+        if isinstance(value, self.enum_class):
+            return value.value
+        elif value is None:
+            return None
+        raise ValueError(f"Invalid value for {self.enum_class}: {value}")
+
+    def process_result_value(self, value, dialect):
+        # int -> enum
+        if value is not None:
+            return self.enum_class(value)
+        return None
 
 class Chat(UUIDBaseModel, UpdatableBaseModel, table=True):
     title: str = Field(max_length=256)
@@ -43,7 +68,8 @@ class Chat(UUIDBaseModel, UpdatableBaseModel, table=True):
     browser_id: str = Field(max_length=50, nullable=True)
     origin: str = Field(max_length=256, default=None, nullable=True)
     visibility: ChatVisibility = Field(
-        sa_column=Column(SmallInteger, default=ChatVisibility.PRIVATE, nullable=False)
+        # sa_column=Column(SmallInteger, default=ChatVisibility.PRIVATE, nullable=False)
+        sa_column=Column(IntEnumType(ChatVisibility), nullable=False, default=ChatVisibility.PRIVATE)
     )
 
     __tablename__ = "chats"