has_many association and parent_id

rubyonrails-talk
1

Rails 3.1.3

Hi everyone again.

I'm trying to develop a database and tables which have the association as follows.

Video 1 ----- 0..n Script

So, in 'script.rb'

class Script < ActiveRecord::Base   belongs_to :video ... end

and in 'video.rb'

class Video < ActiveRecord::Base   has_many :scripts end

Furthermore, in order to refer to the parent (in this case, 'Video'), I need to set video_id:integer for Script. Am I correct ?

in the migration file,

2

Furthermore, in order to refer to the parent (in this case, 'Video'), I need to set video_id:integer for Script. Am I correct ?

Yes.

how can I actually associate a new 'script' entry with its parent, 'video', in making a new 'Script' entry ?

For example, in 'index.html.erb' for NewScript page, I tried to put

<td><%= script.video_id %></td>

I don't understand. index.html.erb is for showing the list of something. What's "NewScript" got to do with it?

You may be on *almost* the right track though. Assuming you get to views/scripts/new.html.erb by clicking on something associated with a video, you can set the new script object's video_id in the controller, and add a hidden field to hold it (for submission to create).

@script.video = Video.where(:video_id)

That where-clause isn't going to work. It's just saying "where there's a valid video_id". Maybe you mean where :video_id => video.id (if there is a variable called video), or maybe video_id.

Anyway, more direct would be simply "@script.video_id = video_id". No searching needed. Assuming of course that you already have the video_id.

BTW, do you know the definition of "Where Clause"? It's a fat guy who dresses up in a red suit and gives out presents, when the moon is full. :wink:

-Dave

3

Thanks for your explanation. When I am confused, it is also difficult to explain what I understand and what I don't. But your guess is right.

"@script.video_id = video_id"

Well, this worked as I wished. It was simpler than I thought!

Thanks again.

soichi

4

It was simpler than I thought!

Rails often is. For example, a while back I was trying to do a simple timesheet system. Couldn't figure out how to force the newly entered entries into the right places. Came up with a hairy and fragile way, that duplicated a lot of what Rails was doing behind the scenes. Correct solution? Don't. Just let Rails do it. No problem. Now I use essentially the same technique in The Decider (http://thedecider.herokuapp.com), to let Rails keep track of which rating in the spreadsheet is for which alternative in which factor.

Thanks again.

You're welcome.

-Dave