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POCan SQLAlchemy eager/joined loads be suppressed once set up?
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  1. POCan SQLAlchemy eager/joined loads be suppressed once set up?
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    copied!<p>I've got a case where most of the time the relationships between objects was such that pre-configuring an eager (joined) load on the relationship made sense. However now I've got a situation where I really don't want the eager load to be done.</p> <p>Should I be removing the joined load from the relationship and changing all relevant queries to join at the query location (ick), or is there some way to suppress an eager load in a query once it is set up?</p> <p>Below is an example where eager loading has been set up on the User->Address relationship. Can the query at the end of the program be configured to NOT eager load?</p> <pre><code>import sqlalchemy as sa from sqlalchemy.ext.declarative import declarative_base import sqlalchemy.orm as orm ##Set up SQLAlchemy for declarative use with Sqlite... engine = sa.create_engine("sqlite://", echo = True) DeclarativeBase = declarative_base() Session = orm.sessionmaker(bind = engine) class User(DeclarativeBase): __tablename__ = "users" id = sa.Column(sa.Integer, primary_key = True, autoincrement = True) name = sa.Column(sa.String, unique = True) addresses = orm.relationship("Address", lazy = "joined", #EAGER LOAD CONFIG IS HERE ) def __init__(self, Name): self.name = Name class Address(DeclarativeBase): __tablename__ = "addresses" id = sa.Column(sa.Integer, primary_key = True, autoincrement = True) address = sa.Column(sa.String, unique = True) FK_user = sa.Column(sa.Integer, sa.ForeignKey("users.id")) def __init__(self, Email): self.address = Email ##Generate data tables... DeclarativeBase.metadata.create_all(engine) ##Add some data... joe = User("Joe") joe.addresses = [Address("joe@example.com"), Address("joeyjojojs@example.net")] s1 = Session() s1.add(joe) s1.commit() ## Access the data for the demo... s2 = Session() #How to suppress the eager load (auto-join) in the query below? joe = s2.query(User).filter_by(name = "Joe").one() # &lt;-- HERE? for addr in joe.addresses: print addr.address </code></pre>
 

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