[sqlalchemy] Re: joining to child, and using child in relation
Tested with trunk. Works, thanks.
On Jan 29, 6:42 am, Michael Bayer wrote:
> OK, well that was painful but we are stronger for the effort, thanks
> for bringing up the issue. r5740 of trunk will allow your original
> mapper(A.join(B))->mapper(B) to configure properly.
>
> On Jan 28, 2009, at 11:28 PM, Michael Bayer wrote:
>
>
>
> > a join is of the form:
>
> > table1.join(table2, onclause)
>
> > such as
>
> > subscriber_table.join(address_table,
> > and_(address_table.c.subscriber_id==subscriber.c.id,
> > address_table.c.type=='MAIN'))
>
> > but unfortunately current relation() code does not support a join of
> > X/
> > Y to Y, unless the join of X/Y is assembled via joined table
> > inheritance. As a workaround, you can wrap your join() in an
> > aliased select(). A fix may be available in the next 10 minutes or
> > maybe not.
>
> > You also could forego the complexity of mapping to a join and just
> > modify your Subscriber class to break up the "addresses" collection
> > amongst a proxy of the "MAIN" element and a list of the remaining
> > elements. an attribute_mapped_collection could help to accomplish
> > this nicely.
>
> > On Jan 28, 2009, at 7:22 PM, GHZ wrote:
>
> >> I have a subscriber and address table.
>
> >> a subscriber will have one and only one 'MAIN' address.
> >> I want the subscriber and MAIN address to be represented by one class
> >> 'Subscriber'. However, I want that class to have a collection
> >> 'addresses' which contains other addresses (e.g. old addresses) - (it
> >> can include the 'MAIN' address too .. or not.. I don't care)
>
> >> subscriber_table = Table('subscriber', metadata,
> >> Column('id', primary_key=True),
> >> autoload=True)
>
> >> address_table = Table('address',
> >> metadata,
> >> Column('subscriber_id', ForeignKey
> >> ('subscriber.id'), primary_key=True),
> >> Column('address_type', primary_key=True),
> >> autoload=True)
>
> >> subscriber_with_default_address = sql.join( subscriber_table.c.id
> >> == address_table.c.subscriber_id).??? <- something to say
> >> address_table.type is 'MAIN'
>
> >> mapper(Address, address_table)
>
> >> mapper(Subscriber, subscriber_and_address, properties={
> >> 'id':[subscriber_table.c.id, address_table.c.subscriber_id],
> >> 'addresses' : relation(Address, collection_class=Addresses,
> >> backref='customer')
> >> })
>
> >> a) I can't quite figure out how to say (address.type is default)
> >> b) even without this I get:
>
> >> sqlalchemy.exc.ArgumentError: Can't determine relation direction for
> >> relationshi
> >> p 'Subscriber.addresses' - foreign key columns are present in both
> >> the
> >> parent an
> >> d the child's mapped tables. Specify 'foreign_keys' argument.
>
> >> if I do specify foreign_keys parameter to the relation function, then
> >> I still get the same.
>
> >> Thanks
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[sqlalchemy] Re: joining to child, and using child in relation
OK, well that was painful but we are stronger for the effort, thanks
for bringing up the issue. r5740 of trunk will allow your original
mapper(A.join(B))->mapper(B) to configure properly.
On Jan 28, 2009, at 11:28 PM, Michael Bayer wrote:
>
>
> a join is of the form:
>
> table1.join(table2, onclause)
>
> such as
>
> subscriber_table.join(address_table,
> and_(address_table.c.subscriber_id==subscriber.c.id,
> address_table.c.type=='MAIN'))
>
> but unfortunately current relation() code does not support a join of
> X/
> Y to Y, unless the join of X/Y is assembled via joined table
> inheritance.As a workaround, you can wrap your join() in an
> aliased select(). A fix may be available in the next 10 minutes or
> maybe not.
>
> You also could forego the complexity of mapping to a join and just
> modify your Subscriber class to break up the "addresses" collection
> amongst a proxy of the "MAIN" element and a list of the remaining
> elements. an attribute_mapped_collection could help to accomplish
> this nicely.
>
>
>
> On Jan 28, 2009, at 7:22 PM, GHZ wrote:
>
>>
>> I have a subscriber and address table.
>>
>> a subscriber will have one and only one 'MAIN' address.
>> I want the subscriber and MAIN address to be represented by one class
>> 'Subscriber'. However, I want that class to have a collection
>> 'addresses' which contains other addresses (e.g. old addresses) - (it
>> can include the 'MAIN' address too .. or not.. I don't care)
>>
>> subscriber_table = Table('subscriber', metadata,
>> Column('id', primary_key=True),
>> autoload=True)
>>
>> address_table = Table('address',
>> metadata,
>> Column('subscriber_id', ForeignKey
>> ('subscriber.id'), primary_key=True),
>> Column('address_type', primary_key=True),
>> autoload=True)
>>
>>
>>
>>subscriber_with_default_address = sql.join( subscriber_table.c.id
>> == address_table.c.subscriber_id).??? <- something to say
>> address_table.type is 'MAIN'
>>
>>mapper(Address, address_table)
>>
>> mapper(Subscriber, subscriber_and_address, properties={
>> 'id':[subscriber_table.c.id, address_table.c.subscriber_id],
>> 'addresses' : relation(Address, collection_class=Addresses,
>> backref='customer')
>> })
>>
>> a) I can't quite figure out how to say (address.type is default)
>> b) even without this I get:
>>
>> sqlalchemy.exc.ArgumentError: Can't determine relation direction for
>> relationshi
>> p 'Subscriber.addresses' - foreign key columns are present in both
>> the
>> parent an
>> d the child's mapped tables. Specify 'foreign_keys' argument.
>>
>> if I do specify foreign_keys parameter to the relation function, then
>> I still get the same.
>>
>> Thanks
>>
>>
>>>
>
>
> >
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[sqlalchemy] Re: joining to child, and using child in relation
a join is of the form:
table1.join(table2, onclause)
such as
subscriber_table.join(address_table,
and_(address_table.c.subscriber_id==subscriber.c.id,
address_table.c.type=='MAIN'))
but unfortunately current relation() code does not support a join of X/
Y to Y, unless the join of X/Y is assembled via joined table
inheritance.As a workaround, you can wrap your join() in an
aliased select(). A fix may be available in the next 10 minutes or
maybe not.
You also could forego the complexity of mapping to a join and just
modify your Subscriber class to break up the "addresses" collection
amongst a proxy of the "MAIN" element and a list of the remaining
elements. an attribute_mapped_collection could help to accomplish
this nicely.
On Jan 28, 2009, at 7:22 PM, GHZ wrote:
>
> I have a subscriber and address table.
>
> a subscriber will have one and only one 'MAIN' address.
> I want the subscriber and MAIN address to be represented by one class
> 'Subscriber'. However, I want that class to have a collection
> 'addresses' which contains other addresses (e.g. old addresses) - (it
> can include the 'MAIN' address too .. or not.. I don't care)
>
>subscriber_table = Table('subscriber', metadata,
>Column('id', primary_key=True),
>autoload=True)
>
>address_table = Table('address',
> metadata,
> Column('subscriber_id', ForeignKey
> ('subscriber.id'), primary_key=True),
> Column('address_type', primary_key=True),
> autoload=True)
>
>
>
> subscriber_with_default_address = sql.join( subscriber_table.c.id
> == address_table.c.subscriber_id).??? <- something to say
> address_table.type is 'MAIN'
>
> mapper(Address, address_table)
>
> mapper(Subscriber, subscriber_and_address, properties={
>'id':[subscriber_table.c.id, address_table.c.subscriber_id],
>'addresses' : relation(Address, collection_class=Addresses,
> backref='customer')
>})
>
> a) I can't quite figure out how to say (address.type is default)
> b) even without this I get:
>
> sqlalchemy.exc.ArgumentError: Can't determine relation direction for
> relationshi
> p 'Subscriber.addresses' - foreign key columns are present in both the
> parent an
> d the child's mapped tables. Specify 'foreign_keys' argument.
>
> if I do specify foreign_keys parameter to the relation function, then
> I still get the same.
>
> Thanks
>
>
> >
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