declarative_base(metadata, model_classes=(<class 'gino.declarative.Model'>, ), name='Model')¶
Mark a class-level method as a factory of attribute.
This is intended to be used as decorators on class-level methods of a
Modelclass. When initializing the class as well as its subclasses, the decorated factory method will be called for each class, the returned result will be set on the class in place of the factory method under the same name.
@declared_attris implemented differently than
declared_attrof SQLAlchemy, but they are both more often used on mixins to dynamically declare indices or constraints (also works for column and
__table_args__, or even normal class attributes):
class TrackedMixin: created = db.Column(db.DateTime(timezone=True)) @db.declared_attr def unique_id(cls): return db.Column(db.Integer()) @db.declared_attr def unique_constraint(cls): return db.UniqueConstraint('unique_id') @db.declared_attr def poly(cls): if cls.__name__ == 'Thing': return db.Column(db.Unicode()) @db.declared_attr def __table_args__(cls): if cls.__name__ == 'Thing': return db.UniqueConstraint('poly'),
This doesn’t work if the model already had a