Rails: violates foreign key constraint

Question

I have three models: Book, genre, BookGenre, and here are relationships:

class BookGenre < ActiveRecord::Base
  bel         


        

Answer 1

Try this:

ActiveRecord::Base.connection.disable_referential_integrity do
    Book.destroy_all
    Genre.destroy_all
    # ...create data 
end

Answer 2

Add dependent: :destroy option to your has_many definitions.

Check docs

Yet better option to respect data integrity is to set the CASCADE DELETE on the database level: say, you have comments table and users table. User has many comments You want to add a foreign_key to table comments and set deleting the comment whenever the user is destroyed you would go with the following (the on_delete: :cascade option will ensure it):

add_foreign_key(
  :comments,
  :users,
  column:
  :user_id,
  on_delete: :cascade
)