um-cseg / chez-betty

        if start:

            r = r.filter(event.Event.timestamp>=start)

        if end:

            r = r.filter(event.Event.timestamp<end)

        return r.one().a or Decimal(0.0)

    # Get the total amount of discounts people have received for keeping

    # money in their account

    @classmethod

    def discounts(cls, start=None, end=None):

        r = DBSession.query(func.sum((cls.amount / (1-cls.discount)) - cls.amount).label('d'))\

                        .join(event.Event)\

                        .filter(cls.discount > 0)\

                        .filter(event.Event.deleted==False)

        if start:

            r = r.filter(event.Event.timestamp>=start)

        if end:

            r = r.filter(event.Event.timestamp<end)

        if distinct_on is None:

            raise NotImplementedError("required argument distinct_on missing")

        r = r.distinct(distinct_on)

        return r.count()

    @classmethod

    def total(cls, start=None, end=None):

        r = DBSession.query(func.sum(cls.amount).label('a'))\

                        .join(event.Event)\

                        .filter(event.Event.deleted==False)

        if start:

            r = r.filter(event.Event.timestamp>=start)

        if end:

            r = r.filter(event.Event.timestamp<end)

class PurchaseLineItem(SubTransaction):

    __mapper_args__ = {'polymorphic_identity': 'purchaselineitem'}

    price           = Column(Numeric)

    def __init__(self, transaction, amount, item, quantity, price, wholesale):

        SubTransaction.__init__(self, transaction, amount, item.id, quantity, wholesale)

        self.price = price

    @classmethod

    def quantity_by_period(cls, period, start=None, end=None):

        r = DBSession.query(cls.quantity.label('summable'), event.Event.timestamp)\

                     .join(Transaction)\

                     .join(event.Event)\

                     .filter(event.Event.deleted==False)\

                     .order_by(event.Event.timestamp)

        if start:

            r = r.filter(event.Event.timestamp>=start.replace(tzinfo=None))

        if end:

        if not trans_type:

            return DBSession.query(cls)\

                            .join(Transaction)\

                            .join(event.Event)\

                            .filter(event.Event.deleted==False)\

                            .order_by(desc(event.Event.timestamp))

        else:

            return DBSession.query(cls)\

                            .join(Transaction)\

                            .join(event.Event)\

                            .filter(cls.type==trans_type)\

                            .filter(event.Event.deleted==False)\

                            .order_by(desc(event.Event.timestamp))

class PurchaseLineItem(SubTransaction):

    __mapper_args__ = {'polymorphic_identity': 'purchaselineitem'}

    price           = Column(Numeric)

    def __init__(self, transaction, amount, item, quantity, price, wholesale):

    @limitable_all

    def all_item_events(cls, id):

        return DBSession.query(cls)\

                        .join(Transaction)\

                        .join(event.Event)\

                        .filter(cls.item_id == id)\

                        .filter(event.Event.deleted==False)\

                        .filter(or_(event.Event.type=="inventory", event.Event.type =="restock"))\

                        .order_by(desc(event.Event.timestamp))

    @classmethod

    @limitable_all

    def all(cls, trans_type=None):

        if not trans_type:

            return DBSession.query(cls)\

                            .join(Transaction)\

                            .join(event.Event)\

                            .filter(event.Event.deleted==False)\

    # Now get all cash deposits between that cash box empty and this one

    q = object_session(self).query(event.Deposit)\

            .filter(event.Event.timestamp < self.timestamp)\

            .order_by(asc(event.Event.timestamp))

    if previous_cb_empty:

        q = q.filter(event.Event.timestamp >= previous_cb_empty.timestamp)

    return q.all()

event.EmptyCashBox.relevant_cash_deposits = __relevant_cash_deposits

################################################################################

## Related Classes

################################################################################

class Purchase(Transaction):

    __mapper_args__ = {'polymorphic_identity': 'purchase'}

    discount = Column(Numeric)

        if start:

            r = r.filter(event.Event.timestamp>=start)

        if end:

            r = r.filter(event.Event.timestamp<end)

        return r.one().c

    @classmethod

    def distinct(cls, *, distinct_on=None, start=None, end=None):

        r = DBSession.query(cls).join(event.Event)\

                .filter(event.Event.deleted==False)

        if start:

            r = r.filter(event.Event.timestamp>=start)

        if end:

            r = r.filter(event.Event.timestamp<end)

        if distinct_on is None: