On Nov 15, 2010, at 8:06 AM, neurino wrote:
> So no advice?
>
> Are relationships and backref something more than attributes I can
> setup with a query?
>
> Thank you for your support.
what's not stated clearly here is what "Root" is. If that's not a class mapped
to a table, then you'd just need to use regular Python attributes and
descriptors to establish the in-python behavior you're looking for. Seems like
its essentially some kind of query object, so your query.all()/.parent =
some_root approach is what you'd go with, though it would appear that Root is a
singleton anyway, meaning this could be established on Area at the class level
instead of assigning to each instance.
Its not clear what other behavior of "relationship()" would apply here, since
Root has no database identity.
>
> On Nov 11, 9:45 am, neurino <neur...@gmail.com> wrote:
>> I have a tree structure
>>
>> Root
>> |
>> +--Area
>> | |
>> | +--SubArea
>> | | |
>> | | +--Item
>> | | |
>> | | +--Item
>> | |
>> | +--SubArea
>> | |
>> | +--Item
>> | |
>> | +--Item
>> |
>> +--Area
>> |
>> +--SubArea
>> | |
>> | +--Item
>> | |
>> | +--Item
>> |
>> +--SubArea
>> |
>> +--Item
>> |
>> +--Item
>>
>> The tree structure corresponds to slqalchemy db tables `areas`,
>> `subareas` and `items`.
>>
>> Something like this:
>>
>> mapper(Area, areas_table, properties={
>> 'subareas': relationship(SubArea, backref='parent'),
>> })
>> mapper(SubArea, subareas__table, properties={
>> 'items': relationship(Item, backref='parent'),
>> })
>> mapper(Item, items_table)
>>
>> so each Area instance will have a `subareas` list and each SubArea
>> will have a `items` list,
>>
>> also I easyly get a backref `parent` from Item to parent SubArea and
>> from
>> SubArea to parent Area.
>>
>> But this won't be for Root: it will not have a `areas` list in Root
>> nor its areas will have a parent reference to Root.
>>
>> The quick-and-dirty solution is to do this in Root:
>>
>> self.areas = query(Area).all()
>> for area in self.areas:
>> area.parent = self
>>
>> But it won't be the same thing as sqlalchemy `relationship` attributes
>> so:
>> are there alternative solutions more sqlalchemy-like?
>>
>> Any tip appreciated!
>>
>> Thank you for your support
>>
>> Greetings
>> neurino
>
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