Triggering a query within a loop

Rails
1

Any help with this would be very appreciated, I’m completely new to
rails. I’m building an application that’s looking to do the following:

First off i’m trying to convert my site from ColdFusion to RoR, this is
the site: http://www.walkenclips.com/

It’s one page that basically does this:

Query the db to get a list of movies (movies table)
Loop through the movies and output each movie to the browser
Query the db within the loop to get files names of movie quotes from
that specific movie (movie_files table)
Loop through the movie quote names and output each quote to the browser
Continue to the next movie, rinse and repeat till the end of the loop

I’m able to display the the movies fine with the following code:

Controller:
class HomeController < ApplicationController
def index
@movie = Movie.find(:all, :order => “title”)
end
end

Index.rhtml
<% for movies in @movie -%>

<%= movies.title %>
<% end %>

movie.rb
class Movie < ActiveRecord::Base
end

While I’m looping through the results in the index.rhtml, how can I tell
the controller I need the movie file names for that specific movie
within the “movie_files” table?

2

in the controller
@movie = Movie.find(:all, :order => “title”)
movie_filed = @movies.movie_files

Off course, you need to define the model first:
class MovieFile < ActiveRecord::Base
belongs_to :movie
end

class Movie < ActiveRecord::Base
has_many :movie_files
end

3

Hi Bill

Bill wrote:

How can I tell the controller I need the movie
file names for that specific movie within the
“movie_files” table?

In general, you’re going to do a find on the movie_files table for each
movie. What the find looks like depends on what your movie_files table
schema looks like.

The other thing you’ll need to address is the data structure to pass to
your
view. My personal preference would probably be to construct a hash of
hashes in the controller, but there are other ways. Share some more
info
and we can probably be of more help.

Best regards,
Bill

4

Bill W. wrote:

Hi Bill

Bill wrote:

How can I tell the controller I need the movie
file names for that specific movie within the
“movie_files” table?

In general, you’re going to do a find on the movie_files table for each
movie. What the find looks like depends on what your movie_files table
schema looks like.

The other thing you’ll need to address is the data structure to pass to
your
view. My personal preference would probably be to construct a hash of
hashes in the controller, but there are other ways. Share some more
info
and we can probably be of more help.

Best regards,
Bill

Thanks for the replies guys, here is my table schema:

movies table
field - type - extra

id - int - auto increment (priamry key)
title - varchar
picture - varchar
year - varchar
rating - varchar
played - varchar
director - varchar

movie_files table
field - type - extra

id - int - auto increment
movie_id - int
name - varchar
downloaded - int
played - int

5

Hi Frank,

Is movie_id declared as a foreign key? It should be. Once it is, you
can
do something like…

movies = Movie.find(:all)
movies.each {|this_movie|
clips = MovieFile.find_all_by_movie_id(this_movie.id)
}

As I noted before, however, you’re going to need to decide how you want
to
structure this data for use in your views. IMHO, there are three
obvious
approaches. 1) You could construct a hash of hashes. 2) You could name
each of the clips arrays so they’re ‘associated’ with some field in your
movies records. Either of these would work with your existing model.
The
hashes approach is cleaner (again IMHO) and there are, of course, other
approaches. The third option is the easiest. 3) De-normalize your
data.

Lest you want to invite the displeasure of the RoRing Gods, the one
thing
you don’t want to do (although it’s certainly possible) is to do the
clips
find in the view.

hth,
Bill

6

Thanks for such a quick response Bill. Since I’m such a newbie to RoR
I’m still a bit confused about method 1 you mentioned. How do I setup
the hashes and have them interact with the view?

7

Hi Frank,

Sorry for my delay in responding. I was out of the office all afternoon
yesterday. Will be again today so please don’t take offense if you have
a
follow-on that I don’t respond to til tomorrow.

I took another look at the models you posted and think perhaps I’ve
misunderstood your needs. My initial understanding was that you had
multiple quotes, and a clip associated with each one, that you wanted
to
output for each movie. In rereading your description, it seems that you
only want to output the quotes. If that’s true, then you don’t need a
hash
of hashes. A hash of arrays will do fine.

If my (new) understanding is correct, in an action in your controller…

@movie_quotes = Hash.new
@movies = Movie.find(:all)
@movies.each {|this_movie|
@movie_quotes[this_movie] =
MovieFile.find_all_by_movie_id(this_movie.id)
}

In your view…

<% @movie_quotes.each do |movie_name, quotes| %>
<%=h( movie_name )%>
<% quotes.each do |this_quote| %>
<%=h( this_quote )%>
<% end %>
<% end %>

hth,
Bill