Ruby on Rails

On Wednesday, January 13, 2016 at 2:22:51 AM UTC-5, Lei Zhang 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

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.

If you want to load matching As without instantiating the Cs, you could do something like:

A.where(id: C.where(code: params[:codes]).pluck(:a_id))

If you are going to instantiate all As and Cs found anyway, you could just use eager loading:

found_c = C.where(code: params[:codes]).includes(:a)

found_a = found_c.collect(&:a).uniq

Jim