HABTM duplicate records

Question

I have a 2 models Game & Theme and they have a has_and_belongs_to_many association. I have tried many solutions to prevent duplicate records in

Answer 1

Creating new Model GameTheme for validation purpose is not a good idea. We can validate itself in migration.

Theme Model:

class Theme < ActiveRecord::Base
  has_and_belongs_to_many :games,
    :association_foreign_key => 'theme_id',
    :class_name => 'Theme',
    :join_table => 'games_themes'
end

Game Model:

class Theme < ActiveRecord::Base
  has_and_belongs_to_many :games,
    :association_foreign_key => 'game_id',
    :class_name => 'Game',
    :join_table => 'games_themes'
end

games_themes migration: You can add uniqueness to join table, Have a look here for more detail.

class GamesThemesTable < ActiveRecord::Migration
  def self.up
    create_table :games_themes, :id => false do |t|
      t.references :game
      t.references :theme
    end

    add_index :games_themes, [:theme_id, :game_id], :unique => true

  end

  def self.down
    drop_table :games_themes
  end
end