On May 24, 2007, at 5:34 PM, Brendan Arnold wrote:
>
> Hi there,
>
> I have a principal object (Person) with another group of objects
> (Address) grafted on through the properties={ 'addresses' :
> relation(Address, secondary = ...)} functions in the mappers
>
> I want to select all Person objects that have particular joined
> objects (i.e. select by joined object's 'id')
>
> If my principal object did not have the 'id' method I could just use
>
> results = model.People.select_by(id=3)
>
> However it does have the id property. I try
>
> query_address = model.Address()
> query_address.id = '13 Cemetary Road'
> results = model.People.select_by(addresses = query_address)
>
thats an interesting hack there. query_address is not persisted, i
dont exactly understand why youd want to go through the effort to
create an object that way, instead of
People.query().join('addresses').filter_by(id=='13 Cemetary
Road').list()
I just checked to see if you could also say:
People.query().join('addresses').select_by(id=='13 Cemetary Road')
but you cant, since select_by() is not looking that we already joined
to 'addresses' whereas filter_by() is. I think perhaps that should
be changed.
> However this only works if _all_ object properties match
>
> Finally I try
>
> results = model.People.select_by(model.address_table.c.id==3)
>
> But this (weirdly) returns _all_ People entries in my table regardless
> of what Address they have.
youre lacking the join between people/addresses and getting a
cartesian product. select_by's "autojoin" behavior only applies to
the string keyword arguments sent to its **kwargs, not the
ClauseElements sent to its *args.
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