Comments on: SQLAlchemy: beware of backref http://pieces.openpolitics.com/2006/07/sqlalchemy-beware-of-backref/ Puzzlings on software development and other topics of interest Thu, 09 Feb 2012 01:00:49 +0000 hourly 1 http://wordpress.org/?v=3.3.1 By: mike bayer http://pieces.openpolitics.com/2006/07/sqlalchemy-beware-of-backref/comment-page-1/#comment-78 mike bayer Mon, 14 Aug 2006 05:04:17 +0000 http://pieces.openpolitics.com/2006/07/sqlalchemy-beware-of-backref/#comment-78 one thing that hasnt been documented, is that SQLAlchemy's backrefs actually have a similarity to Hibernate, in that one side of a bi-directional relationship likes to have a flag on it to indicate that fact, exactly in the same manner as Hibernate's 'inverse="true"' flag; except the flag is called "is_backref". normally, when using the regular "backref" keyword option, the "is_backref" flag is set up by the Backref object that is created. but if you are doing a "manual" backref like in this example, youll want to put "is_backref=True" on the side of the bi-directional relationship that youd like "ignored". also the issue of "cant append to a list without lazy loading its contents first" has been raised repeatedly on the mailing list; eventually i might get around to figuring something out with this one, although its a little involved (i.e., a list you can append() to, but it doesnt know about the rest of its contents...might go with hibernates "extra-lazy-loading" approach). one thing that hasnt been documented, is that SQLAlchemy’s backrefs actually have a similarity to Hibernate, in that one side of a bi-directional relationship likes to have a flag on it to indicate that fact, exactly in the same manner as Hibernate’s ‘inverse=”true”‘ flag; except the flag is called “is_backref”. normally, when using the regular “backref” keyword option, the “is_backref” flag is set up by the Backref object that is created. but if you are doing a “manual” backref like in this example, youll want to put “is_backref=True” on the side of the bi-directional relationship that youd like “ignored”.

also the issue of “cant append to a list without lazy loading its contents first” has been raised repeatedly on the mailing list; eventually i might get around to figuring something out with this one, although its a little involved (i.e., a list you can append() to, but it doesnt know about the rest of its contents…might go with hibernates “extra-lazy-loading” approach).

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