On Nov 6, 2014, at 12:33 AM, Danny Sperry <danny.spe...@gmail.com> wrote:
> About a month ago I ran into a case where I needed to know if an AR object's > association exists dynamically. I was building a CMS Engine. > > I thought maybe this was a one off, but last week I found out my co-worker > also had a need for this in the CMS he was building. So I've come to the > community to see if this is something we think should be added into > ActiveRecord. > > I originally solved for this quite naively with the following solution > > def is_association?(attribute) > respond_to?(attribute) && !attribute_names.include?(attribute.to_s) > end > > and after trying to actually solve it in ActiveRecord I discovered > reflections. I think this is easily solved with something like the following > method inside lib/active_record/assocations.rb or > lib/active_record/relation.rb > > def has_association?(name) > reflections.include? name > end > > I'm new to contributing to open source and have been developing with Rails > for about a year so any and all questions, comments, criticism is welcome. > > Thanks! I’m not certain where this would be useful, since every time I’ve needed to check for an association’s existence it was as a warmup to actually doing something with the reflection object. As an example, this code: if has_association?(:foobar) refl = reflect_on_association(:foobar) … could just as well be written: refl = reflect_on_association(:foobar) if refl … Can you discuss why has_association? would be useful in your code? —Matt Jones
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