On 13 January 2016 at 07:22, Lei Zhang <ray.zhang...@gmail.com> wrote: > I am going to implement a small and simple search feature in my project. But > got a question about the scenario I have right now. So hope to get some tips > from here. > > First of all, this is a rails app. > > There are two models, A and C. > > A has_many C. > > That's to say, it might have some situation like this: > > A1 related to C1, C2, C3, C4 > A2 related to C2, C3, C4, C5 > A3 related to C2, C3, C4, C8 > A4 related to C3, C4, C8, C9 > A5 related to C4, C8, C9, C20
For that you need A has_and_belongs_many C, or (my preferred solution) introduce a join model/table and use has_many through. You can't use has_many as that would require C belongs_to A which is not correct. > > Use C2, C3, C4 as keyword, I can get A1, A2, A3 > Use C4, C8, C9 as keyword, I can get A4, A5 > > I consider that this can be done by using something straightforward like > A.Cs.includes?(C2,C3,C4). > > But that requires an iteration of A. And I concern that it would have some > performance issue. > > Any advice or idea about this requirement ? I don't understand exactly what your requirement is. in particular what do you mean by "use C2, C3, C4 as keyword", when each of the Cs is a record in the db. If you are trying to get all the As related to records C2, C3 and C4 then that is something like (c2.as + c3.as +c4.as).uniq though that may not be the most efficient way. Colin -- You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To unsubscribe from this group and stop receiving emails from it, send an email to rubyonrails-talk+unsubscr...@googlegroups.com. To post to this group, send email to rubyonrails-talk@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/rubyonrails-talk/CAL%3D0gLs1x8Fpeth2BCuNaKWYVAzD6u30MQofK4TTJNKqd%3DnmMw%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
