On Monday, November 5, 2018 at 12:55:57 PM UTC-8, Ben Alavi wrote: > > This gist shows the whole issue we're having: > https://gist.github.com/benalavi/35429576f87c1bd675e81bc19fb80174 > > It looks like when you create an object along w/ multiple related objects > via nested attributes through a one_to_many association validations are run > multiple times (which may be on purpose?) and the reciprocal association > cache on the to_many side is cleared before the 2nd validation (and before > any _save hooks). > > So if you reference the reciprocally associated object in a validation or > save hook it is then queried again for every associated object being saved, > which in our case ended up leading to a substantial performance issue > because we assumed the reciprocal association was preserved. > > Is this a bug? If so I can dig deeper and work on a patch (of course any > advice would be great :)) > > Or is there maybe an option somewhere to change this behavior? Or is this > simply expected behavior for nested attributes? (it doesn't seem to happen > when using adder methods). > > The output from that gist I get is (showing the object_id of the > reciprocal object): > > Creation w/ nested_attributes > Track validate 70306570765160 > Track validate > Track before_save > > Creation using adder w/ given reciprocal reference > Release id: 70306570435020 > Track validate 70306570435020 > Track before_save 70306570435020 >
First, thank you very much for the example you posted and your analysis. It made it very easy to see the problem. The underlying reason for the behavior is that nested_attributes has to validate the associated object during the primary object's validation phase. In general validating the associated object during the saving of the associated object should be skipped, and nested_attributes does do that in the cases where it is calling Model#save manually. However, when creating the associated object, it uses the add_* association method. The add_* association method does not support passing the :validate=>false option to #save, so there isn't a way to tell the object to not validate on save. It can't be added to the nested_attributes plugin, because the nested attributes plugin is generally only added into the classes that need it (the primary object's class), not the associated classes that would need it. To fix the issue you were having, we would have to do one of the following: 1) Add a new plugin that nested_attributes would load into associated classes. 2) Add a method to Sequel::Model itself to skipping validation in Model#save. I try to avoid adding methods to Sequel::Model itself, but in this case I think that's the best approach. This issue is not isolated to nested_attributes, any time you are validating the object before the save and the latter calling #save where you want to skip validating again could benefit from it. I've done a short test of that approach and it passes all existing tests and fixes your issue to avoid the unnecessary "SELECT * FROM `releases` WHERE `id` = ..." queries. I'll add some more tests for the behavior and try to get it committed later today. Thanks, Jeremy -- You received this message because you are subscribed to the Google Groups "sequel-talk" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/sequel-talk. For more options, visit https://groups.google.com/d/optout.
