Association Assistance

[seanf]

I'm looking for some assistance in defining the associations for a project I am working on and would be very grateful for some help. I have the following tables:

Reports
=============
id | name


Sections
=============
id | name


A report can have multiple sections and the user needs to be able to specify the order in which sections will appear in a report. Traditionally I would have added a third table as follows:

Reports_Sections
==================================
report_id | section_id | user_order


I can easily set this up using has_and_belongs_to_many, but how would I go about setting the user_order? Is this the correct association or should I be using a has_many :through? If so, how would I then go about setting the user_order?

Thanks

Sean

[vgarcia]

Use has_many :through. I'd rename the tables slightly though:

Reports
=============
id | name


Sections
=============
id | name


listings
==================================
report_id | section_id | user_order

Then your models:

class Report < ActiveRecord::Base
  has_many :listings, :dependent => true
  has_many :sections, :through => :listings
end

class Section < ActiveRecord::Base
  has_many :listings, :dependent => true
  has_many :reports, :through => :listings
end

class Listing < ActiveRecord::Base
  belongs_to :report
  belongs_to :section
end

Now to show a few examples:

#create sections and reports
home_section = Section.create(:name => 'home')
work_section = Section.create(:name => 'work')
tps_report = Report.create(:name => 'TPS Report')

#bind report to sections
Listing.create(:report => tps_report, :section => work_section, :user_order => 1)
Listing.create(:report => tps_report, :section => home_section, :user_order => 560)

# Access user order given report and section IDs
report = Report.find(1)
puts report.listings.find_by_section_id(1).user_order

#get a count of how many different sections this report is listed in
puts report.sections.size

[seanf]

Thanks Vinnie

Sean