Question

I have a problem in association between two classes, so i have a class table here named Post

Class CreatePosts < ActiveRecord::Migration
  def change
    create_table :posts do |t|
        t.string :post_type , null: false
        t.text :content , null: false
        t.integer :person_id
    end
    add_index :posts, :person_id
    add_index :posts, :group_id
  end
end

and the other one is called Action

class CreateActions < ActiveRecord::Migration
  def change
    create_table :actions do |t|
        t.string :target_type, null:false
            t.integer :target_id
        t.integer :upvote_count
      t.timestamps
    end
      add_index :actions,:target_id
  end
end

so the problem is i want to associate the target_is as the foreign key to the Post class so i did this

class Post < ActiveRecord::Base
    has_one :action
end
class Action < ActiveRecord::Base
    belongs_to :post , :class_name => 'Target', :foreign_key => 'target_id'
end

but is doesn’t work, which when i assign Action object to action method in Post object this error is appeared

Mysql2::Error: Unknown column 'actions.post_id' in 'where clause': SELECT  `actions`.* FROM `actions`  WHERE `actions`.`post_id` = 6 LIMIT 1

so any help?

Answer 1

I suppose you are trying to apply polymorphic association. Try this out.

class Post < ActiveRecord::Base
has_one :action, :as => :target
end

class Action < ActiveRecord::Base
belongs_to :target, :polymorphic => true
end