CODEWITHSUNDEEP
ruby-on-railsassociations
twinturbotom
twinturbotom

Reputation: 1544

Rails belongs_to association returning "Undefined Method" error

I have an article model that should belong to a section. I'm having trouble making this connection work and I receive "Undefined Method" errors when attempting Section.article or Article.section in rails console.

How can I tie these models together to print all articles of a particular section and verify their connection?

I've implemented many solutions from answers and posts and may have mixed things up.

Thank you for your help!

Models (I've also had versions with a forgeign_key or reference entries):

class Article < ActiveRecord::Base
    belongs_to :section
end

class Section < ActiveRecord::Base
    has_many :articles
end

Migration to update tables:

class AddSectionRefToArticles < ActiveRecord::Migration
  def change
    add_reference :articles, :section, index: true
  end
end

Schema.rb

ActiveRecord::Schema.define(version: 20141107123935) do

  # These are extensions that must be enabled in order to support this database
  enable_extension "plpgsql"

  create_table "articles", force: true do |t|
    t.string   "title"
    t.string   "body"
    t.datetime "created_at"
    t.datetime "updated_at"
    t.integer  "section_id"
  end

  add_index "articles", ["section_id"], name: "index_articles_on_section_id", using: :btree

  create_table "sections", force: true do |t|
    t.string   "name"
    t.datetime "created_at"
    t.datetime "updated_at"
  end

end

Upvotes: 1

Views: 1351

Answers (2)

Matt
Matt

Reputation: 14038

What are you actually running on the command line? Section.article or Article.section will not work.

You need to run the relation methods on an instance, not the class itself.

section = Section.create(name: 'Section 1')
section.articles << Article.new(title: 'My article')

section.articles # returns an array of articles belonging to the Section 1 object
Article.last.section # returns the Section 1 object

Upvotes: 3

blelump
blelump

Reputation: 3243

You attempt to use class methods (Section.article or Article.section), whereas associations are defined as instance methods. So that, to call an association you have to call it on an object, e.g: Section.first.articles or Article.last.section

Upvotes: 1

Related Questions