read_database + Sqlalchemy2 = 'ChunkedIteratorResult' object has no attribute 'cursor' when using the ORM

[WilliamStam]

read_database + Sqlalchemy2 = 'ChunkedIteratorResult' object has no attribute 'cursor' when using the ORM

[deanm0000]

What about session.connection() does that work?

[deanm0000]

What about if you pass it the engine instead of the season?

[WilliamStam]

passing the engine in works!

df = polars.read_database(query, connection=engine)

i really thought i was being clever with this issue :P but alas...

---

with engine however, we loose some stuff by letting polars handle the session. in my use-case i set the schema session.execute(text(f"ALTER SESSION SET CURRENT_SCHEMA = MY_SCHEMA")) for oracle and log connections. im guessing you also wont be able to use connection pools then?

seems self.result._metadata.keys works for both as well tho.

[WilliamStam]

got to love sqlalchemy <3 like a billion things for slightly different purposes but essentially very similar

session.connection() works!!

import polars

from sqlalchemy import create_engine, text, String, Integer, select
from sqlalchemy.orm import sessionmaker, mapped_column, Mapped, DeclarativeBase


class Base(DeclarativeBase):
    pass

class SourceTable(Base):
    __tablename__ = "TABLE"


    UPD_SEQ: Mapped[int] = mapped_column(Integer, primary_key=True)
    UPD_VERS1: Mapped[str] = mapped_column(String(2), nullable=True)
    UPD_VERS2: Mapped[str] = mapped_column(String(2), nullable=True)
    UPD_VERS3: Mapped[str] = mapped_column(String(2), nullable=True)


engine = create_engine('oracle+oracledb://***:***@***/***',echo=True)
session_maker = sessionmaker(bind=engine)
session = session_maker()

session.execute(text(f"ALTER SESSION SET CURRENT_SCHEMA = ***"))

query = select(*[
    SourceTable.UPD_SEQ,
    SourceTable.UPD_VERS1,
    SourceTable.UPD_VERS2,
])
query = query.limit(10).offset(0)
query = query.filter(SourceTable.UPD_SEQ > 10)

df = polars.read_database(query, connection=session.connection())
print(df)

the type for connection shows as wrong (it did the same with just session. but was happy with engine)

Expected type 'BasicConnection | BasicCursor | Cursor | Engine | str', got 'Connection' instead

dudethem.. you rock!

[alexander-beedie]

I'll look at handling this more gracefully so it "just works".
Will re-open and assign myself as a reminder ;)

[deanm0000]

session.connection() works!!

Thanks for the feedback. It's always appreciated when people let me know my suggestions work and are helpful.

[alexander-beedie]

@WilliamStam: your query should work in the next release without any modification (keep an eye out for the imminent 0.20.10) 👌