gistfile2.txt

models.py

from sqlalchemy import create_engine
from sqlalchemy import Table, Column, Integer, String
from sqlalchemy import ForeignKey, Boolean
from sqlalchemy.orm import relationship, backref
from sqlalchemy.ext.declarative import declarative_base

engine = create_engine('sqlite:////tmp/bunsen.db', echo=False)

Base = declarative_base()
metadata = Base.metadata

# association table(s)                                                         
dept_insts = Table('department_instructors', metadata,
                   Column('dept_id', String, ForeignKey('department.abbrv')),
                   Column('inst_id', Integer, ForeignKey('instructor.id'))
                   )

class Hasher(object):
    def hash(self):
        raise NotImplemented

class Dept(Base,Hasher):
    __tablename__ = 'department'

    abbrv = Column(String, primary_key=True)
    name  = Column(String)

    def __init__(self, abbrv, name):
        self.abbrv = abbrv
	self.name = name

    def hash(self):
        return {u"abbreviation": self.abbrv, u"name": self.name}

    def __repr__(self):
	return "<Dept('%(abbreviation)s','%(name)s')>" % \
            self.hash()

class Inst(Base,Hasher):
    __tablename__ = 'instructor'

    id    = Column(String, primary_key=True)
    fname = Column(String)
    lname = Column(String)

    departments = relationship('Dept', secondary=dept_insts,
                               backref='instructor')

    def __init__(self, id, fname, lname, depts=None):
	self.id = id
        self.fname = fname
	self.lname = lname
	if not depts:
            self.departments = []
        else:
            self.departments = depts

    def hash(self):
        return {u'fname': self.fname, u'lname': self.lname,
                u'id': self.id,
                u'departments': [d.hash() for d in self.departments]}

    def __repr__(self):
        return "<Inst('%(id)s', '%(fname)s', '%(lname)s')>" % \
            self.hash()

class Class(Base,Hasher):
    __tablename__ = 'classes'

    id   = Column(Integer, primary_key=True)
    dept = Column(Integer, ForeignKey('department.abbrv'), primary_key=True)
    name = Column(String,  nullable=False)

    prereq = None # Needs to be a list of Class refs.                         

    def hash(self):
        return {u'name': self.name, u'id': [self.dept, self.id],
                u'prerequisites': [c.hash() for c in self.prereq]}

    def __repr__(self):
        return "<Class('%(name)s', '%(id)s'>" % \
            self.hash()