Ruby on Rails模型/控制器访问

Question

I have two models, subject and page . I created a one-to-many association between them.

class Subject < ActiveRecord::Base
  has_many :pages
  attr_accessible :name
  attr_accessible :position
  attr_accessible :visible
  attr_accessible :created_at
end

and

class Page < ActiveRecord::Base
  belongs_to :subject

  attr_accessible :subject_id
  attr_accessible :name
  attr_accessible :permalink
  attr_accessible :position
  attr_accessible :visible
  attr_accessible :created_at
end

As mentioned above, I have two models, and I want to access all subject names which are in the Subject model to the page model/controller...

Answer 1

试试看：

Subject.select("subjects.name").joins(:pages).uniq

Answer 2

Below is how you can access subject's pages or page's subject.

s = Subject.create(<params>)
s.pages  # array of page objects

p = Page.create(<params>)
p.subject # subject object

Answer 3

If you want to get all the subjects saved in a subject model use:

Subject.pluck(:name)

or to access a subjects associated with particular page:

page = Page.first
page.subject  #subject object associated with the page