gistfile1.py

"""
sqlalchemy composite column example.
"""

from sqlalchemy import *
from sqlalchemy.orm import *

metadata = MetaData('sqlite://')

vertices = Table('vertices', metadata,
    Column('id', Integer, primary_key=True),
    Column('x1', Integer),
    Column('y1', Integer),
    Column('x2', Integer),
    Column('y2', Integer),
    )

class Point(object):
    def __init__(self, x, y):
        self.x = x
        self.y = y
    def __composite_values__(self):
        return [self.x, self.y]
    def __set_composite_values__(self, x, y):
        self.x = x
        self.y = y
    def __eq__(self, other):
        return other.x == self.x and other.y == self.y
    def __ne__(self, other):
        return not self.__eq__(other)

class Vertex(object):
    def __init__(self, start, end):
        self.start = start
        self.end = end

mapper(Vertex, vertices, properties={
    'start': composite(Point, vertices.c.x1, vertices.c.y1),
    'end': composite(Point, vertices.c.x2, vertices.c.y2)
})

metadata.drop_all()
metadata.create_all()

session = create_session()
v = Vertex(Point(3, 4), Point(5, 6))
session.add(v)
session.flush()

print session.query(Vertex).filter(Vertex.start == Point(3, 4)).all()