Connect two models through id - ruby-on-rails

Question

I have trailer model, and a movie model. When a movie is created, I look up all the available trailers and place each one of them in a record with the youtube link and the movie_id of the movie that's been added.
def index
trailer = Trailer.all
respond_to do |format|
format.json do
render :json => trailer.to_json(:only => [:id, :movie_id, :link])
end
end
end
And the json output,
[
{
"id":1,
"movie_id":"312221",
"link":"LsjX5dqHLuw"
},
{
"id":2,
"movie_id":"209112",
"link":"nIGtF3J5kn8"
},
{
"id":3,
"movie_id":"209112",
"link":"yViIi3gie2c"
},
{
"id":4,
"movie_id":"209112",
"link":"Onh7NbZ7F8o"
},
{
"id":5,
"movie_id":"290250",
"link":"1Vb32Kokbtg"
},
{
"id":6,
"movie_id":"290250",
"link":"1Vb32Kokbtg"
},
{
"id":7,
"movie_id":"27205",
"link":"8hP9D6kZseM"
},
{
"id":8,
"movie_id":"157336",
"link":"ePbKGoIGAXY"
},
{
"id":9,
"movie_id":"157336",
"link":"KlyknsTJk0w"
},
{
"id":10,
"movie_id":"157336",
"link":"nyc6RJEEe0U"
},
{
"id":11,
"movie_id":"157336",
"link":"Lm8p5rlrSkY"
},
{
"id":12,
"movie_id":"157336",
"link":"zSWdZVtXT7E"
}
]
Then I have my movie controller,
def index
#movie = Movie.all
respond_to do |format|
format.json do
render :json => #movie.to_json(include: :trailers)
end
end
end
The the json output,
[
{
"id":1,
"title":"Creed",
"release_date":"2016-01-21",
"image":"/xSE4NBFDzqedwa4AIj99r1Z7ljF.jpg",
"user_id":null,
"created_at":"2016-01-07T20:19:43.849Z",
"updated_at":"2016-01-07T20:19:43.849Z",
"movie_id":"312221",
"backdrop":"/nF4kmc4gDRQU4OJiJgk6sZtbJbl.jpg",
"crew":null,
"cast":null,
"trailers":[
]
},
{
"id":2,
"title":"Batman v Superman: Dawn of Justice",
"release_date":"2016-03-24",
"image":"/eJrlh2g9UGAd7R6mQAOQIIs329H.jpg",
"user_id":null,
"created_at":"2016-01-07T20:21:02.615Z",
"updated_at":"2016-01-07T20:21:02.615Z",
"movie_id":"209112",
"backdrop":"/15PbZtjRJ4zgQA8XS0otL70piQi.jpg",
"crew":null,
"cast":null,
"trailers":[
]
},
{
"id":3,
"title":"The Nice Guys",
"release_date":"2016-05-26",
"image":"/ecD35nDfjsxvDW5BtmK6YAaIkzF.jpg",
"user_id":null,
"created_at":"2016-01-07T20:22:05.960Z",
"updated_at":"2016-01-07T20:22:05.960Z",
"movie_id":"290250",
"backdrop":"/aEMBBMuK3BhKIuFu7iFSTXC41Bi.jpg",
"crew":null,
"cast":null,
"trailers":[
]
},
{
"id":4,
"title":"Inception",
"release_date":"2010-07-22",
"image":"/qmDpIHrmpJINaRKAfWQfftjCdyi.jpg",
"user_id":null,
"created_at":"2016-01-08T09:22:30.383Z",
"updated_at":"2016-01-08T09:22:30.383Z",
"movie_id":"27205",
"backdrop":"/s2bT29y0ngXxxu2IA8AOzzXTRhd.jpg",
"crew":null,
"cast":null,
"trailers":[
]
},
{
"id":5,
"title":"Interstellar",
"release_date":"2014-11-06",
"image":"/nBNZadXqJSdt05SHLqgT0HuC5Gm.jpg",
"user_id":null,
"created_at":"2016-01-08T09:22:39.120Z",
"updated_at":"2016-01-08T09:22:39.120Z",
"movie_id":"157336",
"backdrop":"/xu9zaAevzQ5nnrsXN6JcahLnG4i.jpg",
"crew":null,
"cast":null,
"trailers":[
]
}
]
Is there a way that I can look up all the trailers that have the same movie_id value as a movie and include them into the json render?
The disered result would be something like this,
{
"id":5,
"title":"Interstellar",
"release_date":"2014-11-06",
"image":"/nBNZadXqJSdt05SHLqgT0HuC5Gm.jpg",
"user_id":null,
"created_at":"2016-01-08T09:22:39.120Z",
"updated_at":"2016-01-08T09:22:39.120Z",
"movie_id":"157336",
"backdrop":"/xu9zaAevzQ5nnrsXN6JcahLnG4i.jpg",
"crew":null,
"cast":null,
"trailers":[
{
"id":8,
"movie_id":"157336",
"link":"ePbKGoIGAXY"
},
{
"id":9,
"movie_id":"157336",
"link":"KlyknsTJk0w"
},
{
"id":10,
"movie_id":"157336",
"link":"nyc6RJEEe0U"
},
{
"id":11,
"movie_id":"157336",
"link":"Lm8p5rlrSkY"
},
{
"id":12,
"movie_id":"157336",
"link":"zSWdZVtXT7E"
}
]
}

Answer 1

You can query for trailers by movie_id:
#movie = Movie.first
#trailers = Trailer.where(movie_id: #movie.id)
You might want to research Associations. If your Movie has_many Trailers then you can eventually just do:
#trailers = #movie.trailers
Ruby on Rails Guide: ActiveRecord Associations

Answer 2

You can try to show the trailers in movies
you wan to include trailers with movies in that json
def index
#movies = Movie.order('created_at desc')
respond_to do |format|
format.json do
render :json => #movies.to_json(:include => { :trailers => { :only => [:id, :movie_id, :link] } })
end
end
end
if you want to include particular trailers for movies
then in movie model
For rails > 4
has_many :trailers, -> { where(id: self.movie_id) }