Thanks Fred and Robert and anyone else who has read this! I've had some more time to look at this and it appears there is no way in rails to modify a parent model's attributes from a child model during a transaction. I wrote a basic app to test it out.
Assume Parent has_many Children and Child belongs_to Parent. Also, Parent has a before_save filter (we'll look at what it does in a moment). Child also has a before_filter that updates an attribute in it's Parent. Version 1: In one example, the Parent's before_save filter *builds* three Children. Because it is a "build" and not a new or create, the child objects are saved when the parent is saved. In this case, the child's change to its parent attribute just disappears, although the Child is successfully instantiated. http://pastie.org/1106223 Version 2: Okay, then I tried the same thing, this time using create instead of build in the Parent's before_save filter. That generates an error, "You cannot call create unless the parent is saved." Which makes sense. Version 3: Same as Version 1, but make the Parent's filter after_save. In this case, the before_filter of the children is never called (and same result if the Child's filter is changed to an after_save, it just isn't called). Version 4: Same as Version 1, but remove the callback in the child and just call that method directly from the parent immediately after the build. You get a "undefined method" from the Child's method because the parent is nil at this point. Version 5: Like Version 4, but uses after_save instead of before_save. The results are just like Version 1, the Child's method is called, changes to the Parent aren't saved, but the children are saved. In these examples, I used Parent.create and p=Parent.new p.save and get the same results each time. The results are also in the pastie (http://pastie.org/1106223). So, if there are limitations on what you can do in a callback filter, we should probably documented it somewhere. However, I might even call it a bug. What do you think? d. -- You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en.
