Example #1
def _class_for_table(session, engine, selectable, base_cls, mapper_kwargs):
    selectable = expression._clause_element_as_expr(selectable)
    mapname = _selectable_name(selectable)
    # Py2K
    if isinstance(mapname, unicode): 
        engine_encoding = engine.dialect.encoding 
        mapname = mapname.encode(engine_encoding)
    # end Py2K

    if isinstance(selectable, Table):
        klass = TableClassType(mapname, (base_cls,), {})
        klass = SelectableClassType(mapname, (base_cls,), {})

    def _compare(self, o):
        L = list(self.__class__.c.keys())
        t1 = [getattr(self, k) for k in L]
            t2 = [getattr(o, k) for k in L]
        except AttributeError:
            raise TypeError('unable to compare with %s' % o.__class__)
        return t1, t2

    # python2/python3 compatible system of 
    # __cmp__ - __lt__ + __eq__

    def __lt__(self, o):
        t1, t2 = _compare(self, o)
        return t1 < t2

    def __eq__(self, o):
        t1, t2 = _compare(self, o)
        return t1 == t2

    def __repr__(self):
        L = ["%s=%r" % (key, getattr(self, key, ''))
             for key in self.__class__.c.keys()]
        return '%s(%s)' % (self.__class__.__name__, ','.join(L))

    def __getitem__(self, key):
        return self._query[key]

    for m in ['__eq__', '__repr__', '__lt__', '__getitem__']:
        setattr(klass, m, eval(m))
    klass._table = selectable
    klass.c = expression.ColumnCollection()
    mappr = mapper(klass,

    for k in mappr.iterate_properties:
        klass.c[k.key] = k.columns[0]

    klass._query = session.query_property()
    return klass
Example #2
from sqlalchemy.orm import relationship, backref, relation
from sqlalchemy.dialects import postgresql
from sqlalchemy import select, func, types, sql, update
import datetime
import os
import psycopg2
from wtforms import Form, BooleanField, TextField, PasswordField, validators

database_url = os.environ['DATABASE_URL']
engine = create_engine(database_url, echo=False)
session = scoped_session(sessionmaker(bind=engine, autocommit = False, autoflush = False))

Base = declarative_base()
Base.query = session.query_property()

### Class declarations 

class User(Base):
	__tablename__ = "users"
	id = Column(Integer, primary_key = True)
	user_name = Column(String(64), nullable=True)
	email = Column(String(64), nullable=True)
	password = Column(String(64), nullable=True)
	photos = relationship("Photo", backref="users", lazy="joined")
	# users are the parents of the photo children

class Photo(Base):
	__tablename__ = "photos"