Question

I have a rails app that is tracking social data. The users are going to be able to create groups and add pages(ie. facebook fan pages) to their groups by the page’s social id. Since users could potentially be adding the page as someone else, I have it set up so that there is only one page per social id. I also have a pivot table called Catgorizations that links of the pages to the groups and users.

My model relationships are set up as follows:

User  
    has_many :groups

Group  
    belongs_to :user
    has_many :categorizations  
    has_many :pages, :through => :categorizations  

Page  
    has_many :categorizations  
    has_many :groups, :through => :categorizations

Categorization  
    belongs_to :group  
    belongs_to :page

Now when I create a new page and it saves, it is creating a new categorization. The problem I’m running into is that in the Categorization I need to set the user_id manually. I’ve tried:

@page.categorizations.user_id

But I get an undefined method user_id error. I may be approaching this from the wrong direction but how would I go about setting the user_id of a categorization through the page object?
Also if it matters, I’m using devise to handle my user management stuff.
Any help would be greatly appreciated.
Thanks

Answer 1

What you’re tring to do is to access something several levels deep in a ‘chained’ set of relationships.

In order to access an instance of the User model, given a page, you need to get its categorizations, pick one (how?), get its group, then see what the user_id is of that group.

Conceptually a page will actually have many users that might be in charge of categorizing it.

To get something to happen you could arbitrarily pick the first categorization and then do something with its user:

cat = @page.categorizations.first
user = cat.group.user

I don’t know what you mean about ‘setting’ the user id for the categorization – it doesn’t have a user, so I don’t know what you’ll then want to do with that information, sorry!