migrated to n:m relation, solved #28

app/models/paper.rb

@@ -1,5 +1,5 @@
 class Paper < ActiveRecord::Base
-  belongs_to :author
+  has_and_belongs_to_many :authors
   validates :title, presence: true
   validates :venue, presence: true
   validates :year, presence: true,  numericality: { only_integer: true }

db/migrate/20171109163613_create_papers.rb

@@ -4,7 +4,7 @@ def change
       t.string :title
       t.string :venue
       t.integer :year
-      t.references :author, index: true, foreign_key: true
+
 
       t.timestamps null: false
     end

db/migrate/20171109193956_join_papers_and_authors.rb

@@ -0,0 +1,5 @@
+class JoinPapersAndAuthors < ActiveRecord::Migration
+  def change
+  	create_join_table :authors, :papers
+  end
+end

db/schema.rb

@@ -11,7 +11,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20171109163613) do
+ActiveRecord::Schema.define(version: 20171109193956) do
 
   create_table "authors", force: :cascade do |t|
     t.string   "first_name"
@@ -21,15 +21,17 @@
     t.datetime "updated_at", null: false
   end
 
+  create_table "authors_papers", id: false, force: :cascade do |t|
+    t.integer "author_id", null: false
+    t.integer "paper_id",  null: false
+  end
+
   create_table "papers", force: :cascade do |t|
     t.string   "title"
     t.string   "venue"
     t.integer  "year"
-    t.integer  "author_id"
     t.datetime "created_at", null: false
     t.datetime "updated_at", null: false
   end
 
-  add_index "papers", ["author_id"], name: "index_papers_on_author_id"
-
 end