Ruby on Rails：多态关联，关联表

Question

I'm working on polymorphic association, but how do I correctly call certain values in my database.

If I have these tables

Book table

 id | title            
  1 | give me something
  2 | more title names please

Author table

 id | name
  1 | Author Goods

Review table

 id | author_id | reviewable_id | reviewable_type | review
 1  |    1    |       1       |       Book        | Don't read this book
 2  |    2    |       2       |       Book        | This book is awesome
 3  |    2    |       1       |      Author       | Love this author

My controller looks like this:

@reviews = Review.where(user_id: current_user)

My html loops like this:

<% @reviews.each do |r| %>
  <%= r.author %> <!-- this will give me author information -->
<% end %>

With r.author , I can get information from author, but what if I'm trying to access information of author and book with reviewable_type? I can't do r.reviewable_type because, theres no id association. If I don't have the column book_id like author_id in my Review table, how do I get Book information if my only association through reviewable type is the name of the tables not the id?

I hope my explanation of my issue makes sense.

Answer 1

firstly u dont need author_id in Review if it is polymorphic.

your review.rb should look like

class Review < ActiveRecord::Base
    belongs_to :reviewable, polymorphic: true
end

and your book.rb

class Book < ActiveRecord::Base
    has_many :reviews, as: :reviewable, dependent: :destroy
end

similar should be for your author.rb also

now u dont need to query Review table directly , if u want all current_user reviews simply do

@reviews = current_user.reviews

it will fetch all records from reviews table which have reviewable_id == current_user.id and reviewable_type == "User"

u can similarly query for Books reviews also.