Sqlalchemy: avoiding multiple inheritance and having abstract base class

Question

SQLAlchemy version 0.7.3 introduced the __abstract__ directive which is used for abstract classes that should not be mapped to a database table, even though they are subclasses of sqlalchemy.ext.declarative.api.Base. So now you create a base class like this:

Base = declarative_base()

class CommonRoutines(Base):
    __abstract__ = True

    id = Column(Integer, primary_key=True)

    def __init__(self):
        # ...

Notice how CommonRoutines doesn’t have a __tablename__ attribute. Then create subclasses like this:

class Foo(CommonRoutines):
    __tablename__ = 'foo'

    name = Column(...)

    def __init__(self, name):
        super().__init__()
        self.name = name
        # ...

This will map to the table foo and inherit the id attribute from CommonRoutines.

Source and more information: http://docs.sqlalchemy.org/en/rel_0_7/orm/extensions/declarative.html#abstract

Leave a Comment Cancel reply