diff --git a/pdm.lock b/pdm.lock
index 1cb7186..bc0434c 100644
--- a/pdm.lock
+++ b/pdm.lock
@@ -5,7 +5,7 @@
 groups = ["default"]
 strategy = ["cross_platform", "inherit_metadata"]
 lock_version = "4.4.1"
-content_hash = "sha256:e5b52083ef7f859b75eea32132ef301095ac77b239a08c49229d4a37474b980b"
+content_hash = "sha256:68aec295b130841c79040d9aae40daa7c15c204a7b5756850923308c9460d5b4"
 
 [[package]]
 name = "annotated-types"
@@ -270,6 +270,21 @@ files = [
     {file = "pydantic_core-2.16.3.tar.gz", hash = "sha256:1cac689f80a3abab2d3c0048b29eea5751114054f032a941a32de4c852c59cad"},
 ]
 
+[[package]]
+name = "pydantic-mongo"
+version = "2.1.2"
+requires_python = ">=3.8"
+summary = "Document object mapper for pydantic and pymongo"
+groups = ["default"]
+dependencies = [
+    "pydantic<3.0.0,>=2.0.2",
+    "pymongo<5.0,>=4.3",
+]
+files = [
+    {file = "pydantic-mongo-2.1.2.tar.gz", hash = "sha256:3eb4db8f2eb5abb1e4af4d005c92a2ca0c386c3c8eff125a9174edfe4ffe6633"},
+    {file = "pydantic_mongo-2.1.2-py2.py3-none-any.whl", hash = "sha256:44cc02484eb87e812064cf85130e87b8e5e0fa660cd7188e46f153b7eaf58617"},
+]
+
 [[package]]
 name = "pymongo"
 version = "4.6.2"
diff --git a/pyproject.toml b/pyproject.toml
index 7ff6aa1..b617b11 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -14,6 +14,7 @@ dependencies = [
     "python-dotenv>=1.0.1",
     "motor>=3.3.2",
     "sentry-sdk>=1.42.0",
+    "pydantic-mongo>=2.1.2",
 ]
 requires-python = "==3.12.*"
 readme = "README.md"
diff --git a/simplylab/entity.py b/simplylab/entity.py
index 8eab3cd..b99d800 100644
--- a/simplylab/entity.py
+++ b/simplylab/entity.py
@@ -1,6 +1,6 @@
 import datetime
 from enum import Enum
-from typing import Optional, Annotated
+from typing import Optional, Annotated, Any
 
 from bson import ObjectId
 from pydantic import BaseModel, Field, BeforeValidator, ConfigDict
@@ -39,7 +39,26 @@ class GetChatStatusTodayOutput(BaseModel):
 
 # === mongodb documents start ===
 
-PyObjectId = Annotated[str, BeforeValidator(ObjectId)]
+
+from pydantic import (AfterValidator, GetPydanticSchema,
+                      PlainSerializer, WithJsonSchema)
+from pydantic_mongo import ObjectIdField as _objectIdField
+
+ObjectIdField = Annotated[
+    _objectIdField,
+    AfterValidator(lambda id: _objectIdField(id)),
+    PlainSerializer(lambda id: str(id), return_type=str, when_used='json-unless-none'),
+    WithJsonSchema({'type': 'string'}, mode='serialization'),
+    WithJsonSchema({'type': 'string'}, mode='validation'),
+    GetPydanticSchema(lambda _s, h: h(Any))
+]
+
+
+class Test(BaseModel):
+    id: ObjectIdField = Field(default_factory=ObjectIdField, alias='_id', title='_id')
+
+
+# ObjectIdField = Annotated[str, BeforeValidator(ObjectId)]
 
 
 class MessageRoleType(str, Enum):
@@ -48,13 +67,17 @@ class MessageRoleType(str, Enum):
 
 
 class User(BaseModel):
-    id: PyObjectId = Field(default_factory=PyObjectId, alias="_id")
+    id: ObjectIdField = Field(default_factory=ObjectIdField, alias="_id", title='_id')
     name: str = Field(min_length=3, max_length=100, description="user name")
     created_at: datetime.datetime = Field(default_factory=datetime.datetime.now)
     updated_at: Optional[datetime.datetime] = Field(default=None)
 
     model_config = ConfigDict(
         populate_by_name=True,
+        # json_encoders={
+        #     ObjectId: str,
+        #     datetime: lambda dt: dt.isoformat()
+        # },
         json_schema_extra={
             "example": {
                 "_id": "xxx",
@@ -67,15 +90,15 @@ class User(BaseModel):
 
 
 class Message(BaseModel):
-    id: PyObjectId = Field(default_factory=PyObjectId, alias="_id")
-    conversation_id: PyObjectId = Field()
-    user_id: PyObjectId = Field()
+    id: ObjectIdField = Field(default_factory=ObjectIdField, alias="_id", title='_id')
+    conversation_id: ObjectIdField = Field()
+    user_id: ObjectIdField = Field()
     type: MessageRoleType = Field()
     text: str = Field()
     created_at: datetime.datetime = Field(default_factory=datetime.datetime.now)
-    created_by: PyObjectId = Field()
+    created_by: ObjectIdField = Field()
     updated_at: Optional[datetime.datetime] = Field(default=None)
-    updated_by: Optional[PyObjectId] = Field(default=None)
+    updated_by: Optional[ObjectIdField] = Field(default=None)
 
     model_config = ConfigDict(
         populate_by_name=True,
@@ -96,13 +119,13 @@ class Message(BaseModel):
 
 
 class Conversation(BaseModel):
-    id: PyObjectId = Field(default_factory=PyObjectId, alias="_id")
-    user_id: PyObjectId = Field()
+    id: ObjectIdField = Field(default_factory=ObjectIdField, alias="_id", title='_id')
+    user_id: ObjectIdField = Field()
     title: str = Field()
     created_at: datetime.datetime = Field(default_factory=datetime.datetime.now)
-    created_by: PyObjectId = Field()
+    created_by: ObjectIdField = Field()
     updated_at: Optional[datetime.datetime] = Field(default=None)
-    updated_by: Optional[PyObjectId] = Field(default=None)
+    updated_by: Optional[ObjectIdField] = Field(default=None)
 
     model_config = ConfigDict(
         populate_by_name=True,
@@ -119,18 +142,19 @@ class Conversation(BaseModel):
         },
     )
 
+
 # === mongodb documents end ===
 
 
 class UserConversationMessages(BaseModel):
-    user_id: PyObjectId = Field()
+    user_id: ObjectIdField = Field()
     user_name: str = Field()
-    conversation_id: PyObjectId = Field()
+    conversation_id: ObjectIdField = Field()
     title: str = Field()
     created_at: datetime.datetime = Field(default_factory=datetime.datetime.now)
-    created_by: PyObjectId = Field()
+    created_by: ObjectIdField = Field()
     updated_at: Optional[datetime.datetime] = Field(default=None)
-    updated_by: Optional[PyObjectId] = Field(default=None)
+    updated_by: Optional[ObjectIdField] = Field(default=None)
     messages: list[Message]
 
 
diff --git a/simplylab/main.py b/simplylab/main.py
index 675bf19..f4adb31 100644
--- a/simplylab/main.py
+++ b/simplylab/main.py
@@ -48,6 +48,14 @@ def shutdown_db_client():
     logger.info("Disconnected to the MongoDB database!")
 
 
+@app.exception_handler(Exception)
+async def exception_handler(request: Request, exc: Error):
+    return JSONResponse(
+        status_code=500,
+        content={"message": str(exc)}
+    )
+
+
 @app.exception_handler(Error)
 async def error_handler(request: Request, exc: Error):
     return JSONResponse(
diff --git a/simplylab/providers/user.py b/simplylab/providers/user.py
index 9cf3d01..87d976a 100644
--- a/simplylab/providers/user.py
+++ b/simplylab/providers/user.py
@@ -14,5 +14,6 @@ class UserProvider:
         user = await self.db.user.find_one({"name": user_name})
         if not user:
             user = User(name=user_name)
-            user = await self.db.user.insert_one(user.model_dump())
+            res = await self.db.user.insert_one(user.model_dump())
+            user = await self.db.user.find_one({"_id": res.inserted_id})
         return user