How to add current date time by default on a table declaration? about sqlmodel

[JamesHutchison]

Just going to throw this out there - created at / updated at / soft deleted at are really common patterns and there might be a bit of value to just make them first class features

[FilipeMarch]

This is how I use updated_at:

from sqlmodel import SQLModel, Column, Field
from sqlalchemy import DateTime, func
from typing import Optional
import datetime


class Article(SQLModel, table=True):
    created_at: datetime.datetime = Field(
        default_factory=datetime.datetime.utcnow,
    )
    updated_at: Optional[datetime.datetime] = Field(
        sa_column=Column(DateTime(), onupdate=func.now())
    )

Some people might regard update_at as when a new version of the record was created rather than when the record is updated later on

Personally I believe this does not make much sense.

• When the record is created at 5PM, it was created_at 5PM.
• When the record is updated at 7PM, it was updated_at 7PM.

[FilipeMarch]

I do the same as @antont but without the lambda

from sqlmodel import SQLModel, Field
import datetime


class Article(SQLModel, table=True):
    created_at: datetime.datetime = Field(
        default_factory=datetime.datetime.utcnow,
    )

[firecube-oss]

This is the cleanest way I have found to do it

core_models.py

class SimpleIDModel(BaseModel):
    id: int


class UUIDIDModel(BaseModel):
    id: UUID = Field(default_factory=uuid4)


class TimestampModel(BaseModel):
    created_at: datetime = Field(default_factory=datetime.utcnow)
    updated_at: Optional[datetime]


class EventTimestamp(BaseModel):
    occured_at: Optional[datetime]

consuming.py

class Service(SimpleIDModel, TimestampModel, table=True):
    name: str = Field(nullable=False)
    description: str = Field(nullable=False)

I think having opinionated timestamping might not work.

Some people might regard update_at as when a new version of the record was created rather than when the record is updated later on

[PookieBuns]

It's common to delegate generating timestamps to the database rather than generating them in Python. Much like @FilipeMarch is showing in the update_at column.

In that case you would set the server_default attribute on the column. In the case of sqlalchemy it would look like this: time = db.Column(db.Time, server_default=sqlalchemy.func.now())

I agree it's worth having a firstclass feature for this.

I agree generating timestamp should be dealt with by the database. In this case, I currently use this

class Game(GameBase, table=True):
    created_at: datetime = Field(
        sa_column_kwargs={
            "server_default": text("CURRENT_TIMESTAMP"),
        }
    )

The advantage of this is I don’t need to refer to an actual sa_column, and using CURRENT_TIMESTAMP adheres to ansi sql standards

[antont]

lol I don't know why we had the useless lambda, i guess some mindless copy-paste, thanks, will get to clean those up.

[antont]

We've been doing it like this

from datetime import datetime
from sqlmodel import SQLModel, Field

(...)

created_at: datetime = Field(default_factory=lambda: datetime.now())

[speetpeet]

It's common to delegate generating timestamps to the database rather than generating them in Python. Much like @FilipeMarch is showing in the update_at column.

In that case you would set the server_default attribute on the column. In the case of sqlalchemy it would look like this:
time = db.Column(db.Time, server_default=sqlalchemy.func.now())

I agree it's worth having a firstclass feature for this.

[JamesHutchison]

Yes, I think a mixin might work. I do think it's worth having a discussion how created at / updated at / deleted at would fit with created by / updated by / deleted by (so user IDs, which may be an integer or string type) as well as versioned entities (does created / updated just get replaced with "updated", and "created" is implicit with version 1?)

[mj2068]

The advantage of this is I don’t need to refer to an actual sa_column, and using CURRENT_TIMESTAMP adheres to ansi sql standards

wow, amazing, this is works pretty good with alembic's --autogenerate

def upgrade() -> None:
    # ### commands auto generated by Alembic - please adjust! ###
    op.add_column(
        "users",
        sa.Column(
            "created_at",
            sa.DateTime(),
            server_default=sa.text("CURRENT_TIMESTAMP"),
            nullable=False,
        ),
    )

[antont]

Just going to throw this out there - created at / updated at / soft deleted at are really common patterns and there might be a bit of value to just make them first class features

How would you do it? Maybe a mixin in some library module, that one can use to add features to base SQLModel?

[rafalkrupinski]

Is the solution in #594 (comment) the answer? Can the issue be closed?

[danielqba]

This can be closed.