[Sqlalchemy-tickets] [sqlalchemy] #2722: Unexpected JOIN order (left / right)

[sqlalchemy <mi...@zz...>]

#2722: Unexpected JOIN order (left / right)
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 Reporter:  rbu          |           Owner:  zzzeek
     Type:  defect       |          Status:  new
 Priority:  medium       |       Milestone:
Component:  cextensions  |        Severity:  no triage selected yet
 Keywords:               |  Progress State:  awaiting triage
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 We had quite a hard time figuring out the JOIN order as generated by a
 query(A).join(B) statement. All examples in the documentation have A as
 left and B as right side. Apparently though, when giving an explicit
 criterion as query(A).join(B.a), B will be the left side even when adding
 a select_from.

 Details:

 {{{
 # surprising
 >>> print DBSession.query(User.id).outerjoin(Track.user)
 SELECT user.id AS user_id
 FROM track LEFT OUTER JOIN user ON user.id = track.user_id

 # bug?
 >>> print DBSession.query(User.id).select_from(User).outerjoin(Track.user)
 SELECT user.iduser AS user_id
 FROM track LEFT OUTER JOIN user ON user.id = track.user_id

 # expected
 >>> print DBSession.query(User.id).outerjoin(User.tracks)
 SELECT user.iduser AS user_id
 FROM user LEFT OUTER JOIN track ON user.id = track.user_id
 }}}

 This magic ordering based on the explicit criterion given should be
 covered in the documentation, but we did not find such note.

-- 
Ticket URL: <http://www.sqlalchemy.org/trac/ticket/2722>
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