Relationships

rubyonrails-talk
1

Question: company_user belongs to user, and belongs to company. Then, document belongs to company.

I want to take a user, and grab all of the companies he belongs to, and also grab all of the documents of those companies.

So I want to take user_id, grab the corrosponding company_users, then from there use the company_users' company_id to grab the companies, then from there use the company_id in documents to match up with those companies and grab them.

How do I do that?

Thanks for your time! Ben Lisbakken

2

First off you want

class Company < ActiveRecord::Base has_and_belongs_to_many :users # ... end

class User < ActiveRecord::Base has_and_belongs_to_many :companies # ... end

user = User.find(params[:id]) # assuming a request companies = user.companies user_documents = {} companies.each { |company|   user_documents[company.name] = company.documents # use whatever key is convenient for you }

3

Question: company_user belongs to user, and belongs to company. Then, document belongs to company.

I assume you have models that look something like this.

class User < ActiveRecord::Base   has_many :company_users   has_many :companies, :through => :company_users end

class Company < ActiveRecord::Base   has_many :company_users   has_many :users, :through => :company_users   has_many :documents end

class CompanyUser < ActiveRecord::Base   belongs_to :user   belongs_to :company end

class Document < ActiveRecord::Base   belongs_to :company end

I want to take a user, and grab all of the companies he belongs to, and also grab all of the documents of those companies.

If you have a user, you should be able to simply do the following.

companies = user.companies

if companies.nil?   # deal with the case where no companies were found else   for company in companies     documents = company.documents    # Do whatever with documents.   end end

-- James

4

I haven't read your responses, but here are my models. I'll read them in just a sec... thanks for the quick and great feedback!

class User < ActiveRecord::Base   has_many :company_users end

class CompanyUser < ActiveRecord::Base   belongs_to :company   belongs_to :user end

class Company < ActiveRecord::Base   has_many :company_users   has_many :documents end

class Document < ActiveRecord::Base   belongs_to :company end

-Ben

5

Cool I read both of yours... James yours is more like what I did. I was trying to see if this could be done in one sql statement to grab alllll of it.

Brian, would you suggest I get rid of the company_users table? What fields would I need to add to companies and users?

Thanks again guys! Ben

6

Oops I was confused. Leaving company_users in, and using :through. Can I do habtm :through?

7

errr no… don’t get rid of the company_user table. You need it.

has_and_belongs_to_many is used for pure join tables where it contains just two foreign keys

has_many :through is for join tables that contain additional data, i.e. it’s intended to be used as another full-fledged model

Don’t think in terms of SQL anymore. Let rails handle it. The associations are what let rails automagically generate the SQL statements for you. If you tail -f your development.log you’ll see.

8

You need the table. What you might not need to do is explicitly define the model. That's the main difference between Brian's code and the code I posted. If companies_users stores only the appropriate foreign keys, then use Brian's method. If you need to store more info for a user-company relationship, then my way will work.

-- James

9

It can. Using either Brian's or James' setup, you can do:

user.companies.find(:all, :include => :documents)

Pete Yandell