Source code for sqlalchemy_utils.models

from datetime import datetime

import sqlalchemy as sa

[docs]class Timestamp: """Adds `created` and `updated` columns to a derived declarative model. The `created` column is handled through a default and the `updated` column is handled through a `before_update` event that propagates for all derived declarative models. :: import sqlalchemy as sa from sqlalchemy_utils import Timestamp class SomeModel(Base, Timestamp): __tablename__ = 'somemodel' id = sa.Column(sa.Integer, primary_key=True) """ created = sa.Column(sa.DateTime, default=datetime.utcnow, nullable=False) updated = sa.Column(sa.DateTime, default=datetime.utcnow, nullable=False)
@sa.event.listens_for(Timestamp, 'before_update', propagate=True) def timestamp_before_update(mapper, connection, target): # When a model with a timestamp is updated; force update the updated # timestamp. target.updated = datetime.utcnow() NOT_LOADED_REPR = '<not loaded>' def _generic_repr_method(self, fields): state = sa.inspect(self) field_reprs = [] if not fields: fields = state.mapper.columns.keys() for key in fields: value = state.attrs[key].loaded_value if key in state.unloaded: value = NOT_LOADED_REPR else: value = repr(value) field_reprs.append('='.join((key, value))) return '{}({})'.format(self.__class__.__name__, ', '.join(field_reprs))
[docs]def generic_repr(*fields): """Adds generic ``__repr__()`` method to a declarative SQLAlchemy model. In case if some fields are not loaded from a database, it doesn't force their loading and instead repesents them as ``<not loaded>``. In addition, user can provide field names as arguments to the decorator to specify what fields should present in the string representation and in what order. Example:: import sqlalchemy as sa from sqlalchemy_utils import generic_repr @generic_repr class MyModel(Base): __tablename__ = 'mymodel' id = sa.Column(sa.Integer, primary_key=True) name = sa.Column(sa.String) category = sa.Column(sa.String) session.add(MyModel(name='Foo', category='Bar')) session.commit() foo = session.query(MyModel).options(sa.orm.defer('category')).one(s) assert repr(foo) == 'MyModel(id=1, name='Foo', category=<not loaded>)' """ if len(fields) == 1 and callable(fields[0]): target = fields[0] target.__repr__ = lambda self: _generic_repr_method(self, fields=None) return target else: def decorator(cls): cls.__repr__ = lambda self: _generic_repr_method( self, fields=fields ) return cls return decorator