Rails & Active Record: Complex SQL query

Question

A have 3 Models: Trailer, Movie, Release. Trailer belongs_to a Movie, and a Movie has_many releases and has_many trailers.

I want to render the first trailer of each movie that has a release.

My approach was to create a scope in Trailer.rb:

scope :released, -> {
    joins(:movie).
    where("trailers.movie_id = movies.id").
    joins(:release).
    where.not( :release => nil )
  }

So that I could then call Trailer.released but my query is not working, instead of returning a collection, it's returning an active record relation.

"instead of returning a collection, it's returning an active record relation." They're the same thing. — user229044
– user229044 ♦, Commented Feb 15, 2016 at 21:03
I guess what I'm meaning to say.. I'm expecting to receive an output of Trailer objects. But instead, I'm getting < AtiveRecord Relation #23232 > so I don't know where it's going wrong — Jackson Cunningham
– Jackson Cunningham, Commented Feb 15, 2016 at 21:20
@JacksonCunningham it most likely mean that your SQL is wrong. To make sure relation is valid, call first, for example, on it. It should spit out either the object or the error, saying what's wrong with the query — Andrey Deineko
– Andrey Deineko, Commented Feb 15, 2016 at 21:33

Andrey Deineko · Accepted Answer · 2016-02-15 21:08:01Z

1

scope :released, -> { joins(movie: :releases) }

would return all trailers, which movies have releases.

answered Feb 15, 2016 at 21:08

Andrey Deineko

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1 Comment

Wow, this looks simple. I'll make sure it works then accept, thanks!