this is just wild thinking -- and might not be possible.
I'm wondering if anyone has some ideas on creating a relationship where
only certain columns are queried during relationship loading.
I have a few relationships like this ( pseudocode )
class Tag2Posting:
tag_id INT
posting_id INT
tag = sa.relationship( Tag )
posting = sa.relationship( Posting )
class Tag:
id
name
to_postings = sa.relationship( Tag2Posting )
class Posting:
id INT
to_tags = sa.relationship( Tag2Posting )
accessing the relationship will pull the entire object.
posting_a.to_tags -->generates--> "SELECT tag_id , posting_id FROM
tag_2_posting"
I really only care about the "tag_id" , so I'd want to create a
relationship that generates this sql :
"SELECT tag_id FROM tag_2_posting"
that would probably create either an array of ids:
posting_a.tag_ids = [1,2,3]
a similar , but different, concept would be an object where certain columns
are Deferred when loaded through a relationship ( and normal otherwise ).
this is a bad example, because i'm using a 2 column association object.
but it makes a lot of sense when there's no association object and you end
up querying a ton of data that will not be used.
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