SQLModel Fails to Convert ISO 8601 Datetime Strings to Python datetime Objects

[munishkhatri720]

First Check

• I added a very descriptive title here.
• I used the GitHub search to find a similar question and didn't find it.
• I searched the SQLModel documentation, with the integrated search.
• I already searched in Google "How to X in SQLModel" and didn't find any information.
• I already read and followed all the tutorial in the docs and didn't find an answer.
• I already checked if it is not related to SQLModel but to Pydantic.
• I already checked if it is not related to SQLModel but to SQLAlchemy.

Commit to Help

• I commit to help with one of those options 👆

Example Code

from sqlmodel import SQLModel, Field, Relationship
from datetime import datetime, timezone
from typing import Optional, List
from sqlalchemy import JSON
from sqlalchemy.sql import func
import base64, uuid
import sqlalchemy

class Guild(SQLModel, table=True):
    __tablename__ = "guilds"
    id: int = Field(sa_column=sqlalchemy.Column(sqlalchemy.BigInteger , primary_key=True , index=True)
    )
    client_id: int = Field(
        sa_column=sqlalchemy.Column(sqlalchemy.BigInteger, index=True , primary_key=True)
    )
    blacklisted: bool = Field(default=False)
    prefix: Optional[str] = Field(default=None, nullable=True)
    embed_color: Optional[str] = Field(default=None, nullable=True)
    volume: int = Field(default=75)
    autoplay: bool = Field(default=False)
    buttons: bool = Field(default=True)
    announce: bool = Field(default=True)
    announce_channel: Optional[int] = Field(
        default=None,
        sa_column=sqlalchemy.Column(sqlalchemy.BigInteger, nullable=True),
    )
    leavecleanup: bool = Field(default=False)
    leaveempty: bool = Field(default=False)
    voicestatus: bool = Field(default=True)
    dj_commands: List[str] = Field(default_factory=list, sa_type=JSON)
    dj_role: Optional[int] = Field(
        default=None,
        sa_column=sqlalchemy.Column(sqlalchemy.BigInteger, nullable=True),
    )
    dj_temp: bool = Field(default=False)
    reconnect: bool = Field(default=False)
    text_channel: Optional[int] = Field(
        default=None,
        sa_column=sqlalchemy.Column(sqlalchemy.BigInteger, nullable=True),
    )
    voice_channel: Optional[int] = Field(
        default=None,
        sa_column=sqlalchemy.Column(sqlalchemy.BigInteger, nullable=True),
    )
    reconnect_vc: Optional[int] = Field(
        default=None,
        sa_column=sqlalchemy.Column(sqlalchemy.BigInteger, nullable=True),
    )
    request_channel: Optional[int] = Field(
        default=None,
        sa_column=sqlalchemy.Column(sqlalchemy.BigInteger, nullable=True),
    )
    request_message: Optional[int] = Field(
        default=None,
        sa_column=sqlalchemy.Column(sqlalchemy.BigInteger, nullable=True),
    )
    allowed_channels: List[int] = Field(default_factory=list, sa_type=JSON)
    blocked_channels: List[int] = Field(default_factory=list, sa_type=JSON)
    user_queue_limit: Optional[int] = Field(default=None, nullable=True)
    created_at: datetime = Field(
        default_factory=lambda: datetime.now(timezone.utc),
        sa_column=sqlalchemy.Column(
            sqlalchemy.DateTime(timezone=True), server_default=sqlalchemy.func.now()
        ),
    )
    updated_at: datetime = Field(
        default_factory=lambda: datetime.now(timezone.utc),
        sa_column=sqlalchemy.Column(
            sqlalchemy.DateTime(timezone=True),
            server_default=sqlalchemy.func.now(),
            onupdate=func.now(),
        ),
    )

    class Config:
        arbitrary_types_allowed = True

Description

• Initialized a Guild model with some sample data.
• Checked the type of updated_at and found it to be datetime before calling model_dump_json.
• Called the class method model_dump_json.
• Attempted to call model_validate_json to reconstruct the model from the JSON data.
• Checked the type of updated_at again, but this time, it was of type str.

guild = Guild(id=1, client_id=1)

print(f"Initial Type of Updated At: {type(guild.updated_at)}")

guild_dumped = guild.model_dump_json()

guild_reconstructed = Guild.model_validate_json(guild_dumped)

print(f"Final Type of Updated At: {type(guild_reconstructed.updated_at)}")

print(Guild.__annotations__)

Output:

Initial Type of Updated at : <class 'datetime.datetime'>
Final Type of Updated At : <class 'str'>
{'id': <class 'int'>, 'client_id': <class 'int'>, 'blacklisted': <class 'bool'>, 'prefix': typing.Optional[str], 'embed_color': typing.Optional[str], 'volume': <class 'int'>, 'autoplay': <class 'bool'>, 'buttons': <class 'bool'>, 'announce': <class 'bool'>, 'announce_channel': typing.Optional[int], 'leavecleanup': <class 'bool'>, 'leaveempty': <class 'bool'>, 'voicestatus': <class 'bool'>, 'dj_commands': 
typing.List[str], 'dj_role': typing.Optional[int], 'dj_temp': <class 'bool'>, 'reconnect': <class 'bool'>, 'text_channel': typing.Optional[int], 'voice_channel': typing.Optional[int], 'reconnect_vc': typing.Optional[int], 'request_channel': typing.Optional[int], 'request_message': typing.Optional[int], 'allowed_channels': typing.List[int], 'blocked_channels': typing.List[int], 'user_queue_limit': typing.Optional[int], 'created_at': <class 'datetime.datetime'>, 'updated_at': <class 'datetime.datetime'>}

Operating System

Windows

Operating System Details

Edition	Windows 10 Pro
Version	20H2
Installed on	‎3/‎4/‎2024
OS build	19042.685
Experience	Windows Feature Experience Pack 120.2212.551.0

SQLModel Version

0.0.22

Python Version

Python 3.11.8

Additional Context

No response

[munishkhatri720]

Pydantic version

pydantic-core==2.27.2
pydantic==2.10.4

[munishkhatri720]

If i don't pass table=True it works fine without any issue

from sqlmodel import SQLModel , Field
from datetime import datetime , timezone
from typing import Optional

class Test(SQLModel):
    id : int 
    updated_at : Optional[datetime] = Field(default_factory=lambda : datetime.now(timezone.utc))

t1 = Test(id=1)

print(f"Type of updated_at at the starting is : {type(t1.updated_at)}")

t1d = t1.model_dump_json()

print(t1d)

t2re = Test.model_validate_json(t1d)

print(f"Type of updated_at at the end is : {type(t2re.updated_at)}")

Output:

Type of updated_at at the starting is : <class 'datetime.datetime'>
{"id":1,"updated_at":"2024-12-22T08:06:42.264998Z"}
Type of updated_at at the end is : <class 'datetime.datetime'>

[monchin]

When you are using table=True, don't regard it as pydantic models.
See #1041 #52 #811 etc.
Also see the way to handle this issue by the author