Re: [sqlalchemy] Can't locate strategy for ... (('lazy', 'joined'),)
On 5/21/15 3:56 PM, Russ wrote: nope. I'd need a complete, self-contained and succinct example I can run, thanks Ok, thanks. This is a beefy one so that will be extremely tricky to extract. I had hoped that the combo of lazy+joined would have been a clear indicator since they are opposite loading strategies. the word lazy there is the name of the field. It is the internal equivalent to the lazy argument on relationship: http://docs.sqlalchemy.org/en/rel_1_0/orm/relationship_api.html?highlight=relationship#sqlalchemy.orm.relationship.params.lazy that said, here is exactly what will cause your error. Any of the attribute names defined_items, child_product or number are not in fact bound to a relationship(), and instead refer to a Column-mapped attribute. Looks a lot like number here is a Column. Is that the case? You can't call joinedload for a column attribute. -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To unsubscribe from this group and stop receiving emails from it, send an email to sqlalchemy+unsubscr...@googlegroups.com. To post to this group, send email to sqlalchemy@googlegroups.com. Visit this group at http://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout.
Re: [sqlalchemy] Can't locate strategy for ... (('lazy', 'joined'),)
Yes, 'number' is a column, as you surmised. When I drop that from the path it works fine. The only remaining problem is/was that this ends up loading in every field in the child_product table, and this includes a potentially massive BSON column (and more). After looking into this, I've now learned about deferred, defer, undefer, loadonly, etc. This seems to be the correct way to manage this, and it appears to be working fine: q = q.options(sa.orm .joinedload(defined_items) .joinedload(child_product) .load_only(number) ) Thanks for pointing me in the right direction! This page had the info I needed: http://docs.sqlalchemy.org/en/latest/orm/loading_columns.html Russ On Thursday, May 21, 2015 at 4:01:16 PM UTC-4, Michael Bayer wrote: On 5/21/15 3:56 PM, Russ wrote: nope. I'd need a complete, self-contained and succinct example I can run, thanks Ok, thanks. This is a beefy one so that will be extremely tricky to extract. I had hoped that the combo of lazy+joined would have been a clear indicator since they are opposite loading strategies. the word lazy there is the name of the field. It is the internal equivalent to the lazy argument on relationship: http://docs.sqlalchemy.org/en/rel_1_0/orm/relationship_api.html?highlight=relationship#sqlalchemy.orm.relationship.params.lazy that said, here is exactly what will cause your error. Any of the attribute names defined_items, child_product or number are not in fact bound to a relationship(), and instead refer to a Column-mapped attribute. Looks a lot like number here is a Column. Is that the case? You can't call joinedload for a column attribute. -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To unsubscribe from this group and stop receiving emails from it, send an email to sqlalchemy+unsubscr...@googlegroups.com. To post to this group, send email to sqlalchemy@googlegroups.com. Visit this group at http://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout.
Re: [sqlalchemy] Can't locate strategy for ... (('lazy', 'joined'),)
On 5/21/15 3:25 PM, Russ wrote:
I have a query I am running where sqlalchemy is throwing this exception:
Exception: can't locate strategy for class
'sqlalchemy.orm.properties.ColumnProperty' (('lazy', 'joined'),)
What causes this is the addition of this joinedload_all option to a
query (q):
q = q.options(sa.orm.joinedload_all(defined_items.child_product.number))
The intent of adding that is to try and avoid emitting sql when
accessing foo.defined_items[x].child_product.number, as there are many
defined_items.
There are several other joined loads on this query that don't have an
issue. Any ideas on what would be causing this particular problem?
nope. I'd need a complete, self-contained and succinct example I can
run, thanks.
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[sqlalchemy] Can't locate strategy for ... (('lazy', 'joined'),)
I have a query I am running where sqlalchemy is throwing this exception:
Exception: can't locate strategy for class
'sqlalchemy.orm.properties.ColumnProperty' (('lazy', 'joined'),)
What causes this is the addition of this joinedload_all option to a query
(q):
q = q.options(sa.orm.joinedload_all(defined_items.child_product.number))
The intent of adding that is to try and avoid emitting sql when accessing
foo.defined_items[x].child_product.number, as there are many defined_items.
There are several other joined loads on this query that don't have an
issue. Any ideas on what would be causing this particular problem?
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Re: [sqlalchemy] Can't locate strategy for ... (('lazy', 'joined'),)
nope. I'd need a complete, self-contained and succinct example I can run,
thanks
Ok, thanks. This is a beefy one so that will be extremely tricky to
extract. I had hoped that the combo of lazy+joined would have been a clear
indicator since they are opposite loading strategies.
Digging through the relationship definitions I thought it might be because
the child_product relationship is explicitly declared with lazy = True
('select') and (since I don't do that on other properties) I thought
perhaps that was conflicting with the later joinedload request and
confusing the strategy lookup. However, I see that True/select is the
default, and I explicitly request joinedload at query time on other
relationships/properties without issue, so that can't be it. I'm stumped
again.
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