On Tue, May 12, 2009 at 07:47:10PM -0400, Andrew Peace wrote:
> class Item(SQLObject):
> """An item definition (e.g. 'The Life of Brian DVD')"""
> name = StringCol(length=15, alternateID=True)
> attributes = MultipleJoin('ItemAttribute')
>
> class Attribute(SQLObject):
> """An attribute definition (e.g. ISBN is a String)"""
> #columns
> name = StringCol(length=10, alternateID=True)
> title = StringCol(length=20)
> dataType = IntCol(length=1)
>
> class ItemAttribute(SQLObject):
> """An attribute instantiation (e.g. ISBN='abcd1234')"""
> item = ForeignKey('Item', cascade=True)
> attribute = ForeignKey('Attribute')
> value = StringCol(length=50)
>
> SELECT item.*
> FROM item
> LEFT JOIN item_attribute as item_attribute0 ON item.id =
> item_attribute0.item_id
> LEFT JOIN attribute as attribute0 on attribute0.id =
> item_attribute0.attribute_id
> LEFT JOIN item_attribute as item_attribute1 ON item_attribute0.item_id
> = item_attribute1.item_id
> LEFT JOIN attribute as attribute1 on attribute1.id =
> item_attribute1.attribute_id
> WHERE 1
> AND attribute0.name = 'price'
> AND item_attribute0.value = '19.99'
> AND attribute1.name = 'isbn'
> AND item_attribute1.value = 'life123';
from sqlobject.sqlbuilder import Alias, LEFTJOINOn
attribute0 = Alias(Attribute, 'attribute0')
item_attribute0 = Alias(ItemAttribute, 'item_attribute0')
item_attribute1 = Alias(ItemAttribute, 'item_attribute1')
and then something like this:
Item.select(
join=[
LEFTJOINOn(None, item_attribute0, Item.q.id == item_attribute0.q.itemID),
LEFTJOINOn(None, attribute0, attribute0.q.id ==
item_attribute0.q.attributeID),
... other left joins ...
],
clause = (
(attribute0.q.name == 'price') &&
(item_attribute0.q.value == 19.99) &&
... other where clauses ...
)
)
Or, if you prefer this form
clause = AND(
(attribute0.q.name == 'price'),
(item_attribute0.q.value == 19.99),
... other where clauses ...
)
Oleg.
--
Oleg Broytmann http://phd.pp.ru/ p...@phd.pp.ru
Programmers don't die, they just GOSUB without RETURN.
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