Relationships

Rails
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 L.

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

On 9/21/06, Ben L. [email protected] wrote:

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

On 22/09/2006, at 8:03 AM, Ben L. wrote:

I
was trying to see if this could be done in one sql statement to grab
alllll of it.

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

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

Pete Y.

9

On 9/21/06, Ben L. [email protected] wrote:

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

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