I have been learning rails and building blogs site and introduced the like model for posts. I have created a like model for liking a blog post using polymorphic association with user user_id and blogs blog_id. and i want to have a like button for a comments on each blog post, and i don't know which way to do is better

1. can i have a comment_id on the same like model , will it be correct or may break polymorphic association
   or
   
2. Should i make a totally different like model for comments with user_id and comment_id as a foreign key

CodePudding user response：

You should use Polymorphic Association here. But I notice that you have the wrong understanding of Polymorphic Association in the above explanation because you are referencing Blog & Comment via blog_id & comment_id respectively in the Like model instead of referencing those through likeable(i.e., likeable_id & likeable_type). Follow the below steps for better understanding.

• Generate Like model

rails g model Like user:references likeable:references{polymorphic}

• Like model migration should look like this

class CreateLikes < ActiveRecord::Migration[6.1]
  def change
    create_table :likes do |t|
      t.references :user, null: false, foreign_key: true
      t.references :likeable, polymorphic: true, null: false

      t.timestamps
    end
  end
end

• Like model

class Like < ApplicationRecord
  belongs_to :user
  belongs_to :likeable, polymorphic: true
end

• Blog model

class Blog < ApplicationRecord
  has_many :likes, as: :likeable
end

• Comment model

class Comment < ApplicationRecord
  has_many :likes, as: :likeable
end

• Table entries of Like model should look similar to this

 => #<Like:0x00# id: 1, user_id: 1, likeable_id: 1, likeable_type: "Blog", created_at: <timestamp>, updated_at: <timestamp>>

 => #<Like:0x00# id: 2, user_id: 1, likeable_id: 2, likeable_type: "Comment", created_at: <timestamp>, updated_at: <timestamp>>