Is dynamic schema supported like in SQLAlchemy?

[aghanti7]

First Check

• I added a very descriptive title to this issue.
• I used the GitHub search to find a similar issue and didn't find it.
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• 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.

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Example Code

Example code from the blog:

Base = declarative_base()

class MyTableClass(Base):
	__tablename__ = 'myTableName'
	myFirstCol = Column(Integer, primary_key=True)
	mySecondCol = Column(Integer, primary_key=True)


Base.metadata.create_table(engine)

attr_dict = {'__tablename__': 'myTableName',
	     'myFirstCol': Column(Integer, primary_key=True),
	     'mySecondCol': Column(Integer)}

Description

I am looking if SQLModel supports dynamic schema like SQLAlchemy does. Example: https://sparrigan.github.io/sql/sqla/2016/01/03/dynamic-tables.html

Operating System

macOS

Operating System Details

No response

SQLModel Version

0.0.4

Python Version

3.9.0

Additional Context

No response

[RobertRosca]

Would PR #43 solve this when merged?

[aghanti7]

I was able to achieve this with the below workaround.

class UserActivityBase(SQLModel):
    # One table per user
    # Created first time when a user logs in perhaps
    created_ts: datetime.datetime = Field(primary_key=True)
    activity_type: str
    activity_value: float


async def create_user_activity_model(uuid: str, engine: AsyncEngine):
    class UserActivity(UserActivityBase, table=True):
        __tablename__ = 'user_activity_' + uuid
        __table_args__ = {'schema': 'user_schema',
                                       'keep_existing': True}

    # Create the table if needed
    async with engine.begin() as conn:
        await conn.run_sync(SQLModel.metadata.create_all)
    return UserActivity


class UserActivityCrud(UserActivityBase):
    pass


async def get_user_activity_model(uuid: str):
    class UserActivityCrud(UserActivityBase, table=True):
        __tablename__ = 'user_activity_' + uuid
        __table_args__ = {'schema': 'user_schema',
                                       'keep_existing': True}

    return UserActivityCrud

UserActivityBase is the base SQLModel. When you want to create the table for a new user, you can call create_user_activity_model() with the user's uuid and the engine instance. Later, when you need to get the model for a particular user, just call get_user_activity_model(uuid=<uuid>).

The only thing I am facing is a warning. When you call get_user_activity_model more than once, the below warning is thrown.

/Users/ghanti/code/proj/venv/lib/python3.9/site-packages/sqlmodel/main.py:367: SAWarning: This declarative base already contains a class with the same class name and module name as app.models.UserActivityCrud, and will be replaced in the string-lookup table.

I feel this can be ignored. @tiangolo can you please confirm?