On Feb 26, 2010, at 3:23 PM, Kent wrote:
> It *sounds* like exactly what I'm looking for, but when I try a simple
> example, it doesn't seem to work:
>
>>>>
>>>> ol=OrderDetail()
>>>> ol.productid = 'DININGCHAIR'
>>>> DBSession.query(Product).with_parent(ol).all()
> 15:21:57,688 INFO [sqlalchemy.engine.base.Engine.0x...d3d0] BEGIN
> 15:21:57,694 INFO [sqlalchemy.engine.base.Engine.0x...d3d0] SELECT
this is not the correct usage. the OrderDetail must be persistent, not
transient. When you say OrderDetail(), it has no primary key, and then ask
for the Product which is a parent, there is no such Product in the database
since there is no such OrderDetail.
In your case above, you have a productid already so I would think a simple
get() for product would suffice.
> products.productid AS products_productid, products.brand AS
> products_brand, products.vendorsku AS products_vendorsku,
> products.stockeditem AS products_stockeditem,
> products.packagesplittype AS products_packagesplittype,
> products.packagecomponent AS products_packagecomponent,
> products.productgroup AS products_productgroup, products.productfamily
> AS products_productfamily, products.productsubfamily AS
> products_productsubfamily, products.description AS
> products_description, products.regular AS products_regular,
> products.commissiontype AS products_commissiontype,
> products.replacementcost AS products_replacementcost, products.sale AS
> products_sale, products.onhand AS products_onhand, products.onorder AS
> products_onorder, products.imageurl AS products_imageurl,
> products.special AS products_special, products.featured AS
> products_featured, products.newproduct AS products_newproduct
> FROM products
> WHERE products.productid = %(param_1)s
> 15:21:57,694 INFO [sqlalchemy.engine.base.Engine.0x...d3d0]
> {'param_1': None}
> []
>>>>
>
>
> I had expected the bind variable param_1 to equal the fk of
> 'DININGCHAIR'
>
> What am I missing?
>
>
>
>
> On Feb 26, 2:50 pm, Michael Bayer <mike...@zzzcomputing.com> wrote:
>> On Feb 26, 2010, at 1:48 PM, Kent wrote:
>>
>>
>>
>>> I'm certain sqlalchemy's got a function call in its guts that I was
>>> about to recreate from scratch, so I'm hoping you can spare me the
>>> trouble.
>>
>>> I'm trying to construct the foreign key where clause and from clause
>>> needed to populate a relation.
>>
>>> I'd explain how I got here, but might take several days, so instead,
>>> is there a function call to help me?
>>
>>> In other words, I've got an object, for example an order:
>>
>>> ===================================
>>
>>> orderdetail_table = Table("orderdetails",metadata,
>>> Column("orderid", Unicode, ForeignKey('orders.orderid'),
>>> primary_key=True),
>>> Column("lineid", Integer, primary_key=True),
>>> Column("saleprice", Numeric, nullable=False),
>>> Column("productid", Unicode(255),
>>> ForeignKey('products.productid'), nullable=False)
>>> )
>>
>>> product_table = Table("products", metadata,
>>> Column("productid", Unicode(255), primary_key=True),
>>> Column("brand", Unicode(255),
>>> ...
>>> )
>>
>>> class Order(object):
>>> pass
>>
>>> class OrderDetail(object):
>>> pass
>>
>>> # ---------------------------- OrderDetail
>>> -------------------------------------------------------- #
>>> orderdetail_mapper = mapper(OrderDetail, orderdetail_table,
>>> allow_null_pks=False,
>>> properties=dict(product=relation(Product,
>>> cascade='refresh-expire,expunge', #don't save
>>> changes to Product
>>> lazy=False)))
>>
>>> =====================
>>
>>> Say the 'product' relation is not populated on a *transient*
>>> OrderDetail object that I will not be issuing a session flush() for
>>> (there are errors detected.. but that's the long story).
>>
>>> I want to populate the transient OrderDetails 'product' attribute with
>>> the detached product.
>>
>>> I assume there is no way a refresh of the 'product' attribute will
>>> accomplish this since the parent obj is transient (which would really
>>> be what I want), so I am also assuming I'll need to build the pk
>>> clause and issue a session.query.get().
>>
>>> Since this is dynamic code (accepting any sqla object), I need to
>>> dynamically construct that pk clause and from clause based on the
>>> mapper's RelationProperty. In other words, use _foreign_keys to
>>> construct this ?
>>
>>> But I imagine there is already a function call that will get me what I
>>> want.
>>
>>> In the end, for this example, I'd want to dynamically build
>>> session.query(Product).filter( * pk clause based on fks *)
>>
>>> Is there a function that can get me most everything I want (return the
>>> pk clause) or must I build that up myself, and if myself, do you
>>> recommend the RelationProperty's _foreign_keys attribute as the
>>> starting point?
>>
>>> Thanks in advance, again.
>>
>> are you perhaps looking for sess.query(Product).with_parent(someorder) ?
>> there's an example here:
>> http://www.sqlalchemy.org/docs/mappers.html#building-query-enabled-pr...
>>
>>
>>
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>>
>>
>
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