def reference_col(tablename, nullable=False, pk_name='id', **kwargs):
"""Column that adds primary key foreign key reference.
Usage: ::
category_id = reference_col('category')
category = relationship('Category', backref='categories')
"""
return db.Column(ForeignKey('{0}.{1}'.format(tablename, pk_name)),
nullable=nullable,
**kwargs)
class SurrogatePK(object):
"""A mixin that adds a surrogate integer 'primary key' column named ``id`` to any declarative-mapped class."""
__table_args__ = {'extend_existing': True}
id = db.Column(db.Integer, primary_key=True)
@classmethod
def get_by_id(cls, record_id):
"""Get record by ID."""
if any((isinstance(record_id, basestring)
and record_id.isdigit(), isinstance(record_id,
(int, float))), ):
return cls.query.get(int(record_id))
return None