has_many, :through => :multiple

Question

I would like a relationship along the lines of

has_many :foos, :through => :multiple

models

Site:

has_many :pages
has_many :files

Page:

belongs_to :site
has_many :legacy_url_redirects, as: :redirect_resourceable

File:

belongs_to :site
has_many :legacy_url_redirects, as: :redirect_resourceable

LegacyUrlRedirects

belongs_to :redirect_resourceable, :polymorphic => true

What I would like to do is in the Site model add something like:

has_many :legacy_url_redirects, :through => [:pages, :files]

Or an equally good alternative.

Thanks.

EDIT:

Here is what i did: Site model:

def legacy_url_redirects(options = {})
  file_where = {"files.site_id" => self.id}.merge(options)
  page_where = {"pages.site_id" => self.id}.merge(options)

  LegacyUrlRedirect.includes(:file).where(file_where) + LegacyUrlRedirect.includes(:page).where(page_where) 
end

I also added the :pages and :files relationships to the LegacyUrlRedirects model with help from: https://stackoverflow.com/a/16124295/1141264

SECOND EDIT:

I refactored the fix a little so that its a manually written LEFT OUTER JOIN between the three tables. Also not specifying the select part of the query when doing a join implies @readonly = true on the records returned.

it looks like your files and pages should be subclasses of a more general model. After which you can put the :through => ... pointing to the superclass of both the page and file. — Enermis, Dec 12 '13 at 11:48
Maybe this other answer helps you: http://stackoverflow.com/a/15489963/1022165 — Thyago B. Rodrigues, Dec 12 '13 at 11:54
@Enermis Good idea, but apart from this relationship and a url its the only thing they will share, not sure it warrants a superclass. — DickieBoy, Dec 12 '13 at 12:02
@Thayago B. Rodrigues eager loading the relationship brings up an ActiveRecord::EagerLoadPolymorphicError — DickieBoy, Dec 12 '13 at 12:08
oh no, why would you do that? just create two `has_many` relations. — phoet, Dec 12 '13 at 13:30

has_many, :through => :multiple

0 Answers0