gistfile1.py

"""The application's model objects"""
import sqlalchemy as sa
from sqlalchemy import orm
import re
from central_library.model import meta

def init_model(engine):
    """Call me before using any of the tables or classes in the model"""

    sm = orm.sessionmaker(autoflush=True, autocommit=False, bind=engine)

    meta.engine = engine
    meta.Session = orm.scoped_session(sm)
    meta.Session.mapper(User, users_table, properties = {"loans": orm.relation(Loan, backref='user')})
    meta.Session.mapper(Entity, entities_table, properties = {"items": orm.relation(Item, backref='entity')})
    meta.Session.mapper(Item, items_table, properties = {"loans": orm.relation(Loan, backref='item')})
    meta.Session.mapper(Loan, loans_table)

users_table = sa.Table("users", meta.metadata,
    sa.Column("user_id", sa.types.Integer, primary_key=True),
    sa.Column("name", sa.types.Unicode(200), nullable=False),
    sa.Column("address", sa.types.UnicodeText, nullable=False),
    sa.Column("is_staff", sa.types.Boolean, nullable=False, default=False)
)

entities_table = sa.Table("entities", meta.metadata,
    sa.Column("entity_id", sa.types.Integer, primary_key=True),
    sa.Column("title", sa.types.Unicode(200), nullable=False),
    sa.Column("author", sa.types.Unicode(200), nullable=False),
    sa.Column("ean", sa.types.String(13), nullable=True, unique=True),
    sa.Column("pub_date", sa.types.Date, nullable=True),
    sa.Column("kind", sa.types.String(50), nullable=False),
)

items_table = sa.Table("items", meta.metadata,
    sa.Column("item_id", sa.types.Integer, primary_key=True),
    sa.Column("entity_id", sa.types.Integer, sa.ForeignKey("entities.entity_id"), nullable=False),
    sa.Column("acquired_date", sa.types.Date, nullable=False),
    sa.Column("condition_notes", sa.types.UnicodeText, nullable=True),
)

loans_table = sa.Table("loans", meta.metadata,
    sa.Column("user_id", sa.types.Integer, sa.ForeignKey("users.user_id"), primary_key=True),
    sa.Column("item_id", sa.types.Integer, sa.ForeignKey("items.item_id"), primary_key=True),
    sa.Column("due_date", sa.types.Date, primary_key=True),
)

class OrmObject(object):
    pass
    # def __init__(self, **kwargs):

class User(OrmObject):
    def __repr__(self):
        return "<User('%d', '%s', '%s', '%s')>" % (self.user_id, self.name, self.address, self.is_staff)

class Entity(OrmObject):
    @orm.validates('kind')
    def _validate_kind(self, key, kind):
        assert kind in ['book', "video", "audio", "software"]
        return kind
    @orm.validates('ean')
    def _validate_ean(self, key, ean):
        ean = re.sub(r"\D", "", ean)
        assert len(ean) == 13
        return ean
    
class Item(OrmObject):
    pass

class Loan(OrmObject):
    pass