8.30. SQLAlchemy Query About

8.30. SQLAlchemy Query About — Python

8.30.1. Query

https://docs.sqlalchemy.org/en/stable/orm/query.html#sqlalchemy.orm.Query.__init__

8.30.2. With Session

https://docs.sqlalchemy.org/en/stable/orm/query.html#sqlalchemy.orm.Query.with_session

8.30.3. Select Columns

https://docs.sqlalchemy.org/en/stable/orm/loading_columns.html#sqlalchemy.orm.defer
https://docs.sqlalchemy.org/en/stable/orm/loading_columns.html#sqlalchemy.orm.deferred
https://docs.sqlalchemy.org/en/stable/orm/loading_columns.html#sqlalchemy.orm.load_only

>>> from sqlalchemy.orm import defer
>>> from sqlalchemy.orm import undefer
>>>
>>> session.query(Book).options(
...     defer('*'), undefer('summary'), undefer('excerpt'))

A similar function is available with less verbosity by using the load_only() option. This is a so-called exclusionary option which will apply deferred behavior to all column attributes except those that are named:

>>> from sqlalchemy.orm import load_only
>>>
>>> session.query(Book).options(load_only(Book.summary, Book.excerpt))