Rails 4 - destroying a HABTM record results in UndefinedTable

Question

I have a has_and_belongs_to_many relationship between Events and Users.

user.rb

class User < ActiveRecord::Base
  rolify
  has_and_belongs_to_many :events, join_table: :events_users
  after_create :assign_default_role

  devise :database_authenticatable, :registerable,
         :recoverable, :rememberable, :trackable, :validatable

   def assign_default_role
     add_role(:basic)
   end
end

event.rb

class Event < ActiveRecord::Base
  rolify
  has_and_belongs_to_many :users, join_table: :events_users
end

When I want to delete an Event I do two things:

1. remove all associations (from events_users table)
2. destroy the Event (from events table)

So I wrote this code to accomplish that:

events_controller.rb

  def destroy
    @event.users.clear #remove all associations
    @event.destroy #destroy event

    respond_to do |format|
      flash[:success] = 'Event was successfully deleted.'
      format.html { redirect_to events_url }
      format.json { head :no_content }
    end
  end

Clearing associations in the join table works fine (@event.users.clear).

I get an error when it tries to destroy the actual Event (@event.destroy).

  (0.7ms)  BEGIN
  SQL (0.4ms)  DELETE FROM "events_users" WHERE "events_users"."event_id" = $1  [["event_id", 13]]
PG::UndefinedTable: ERROR:  relation "events_roles" does not exist
LINE 5:                WHERE a.attrelid = '"events_roles"'::regclass
                                          ^
:               SELECT a.attname, format_type(a.atttypid, a.atttypmod),
                     pg_get_expr(d.adbin, d.adrelid), a.attnotnull, a.atttypid, a.atttypmod
                FROM pg_attribute a LEFT JOIN pg_attrdef d
                  ON a.attrelid = d.adrelid AND a.attnum = d.adnum
               WHERE a.attrelid = '"events_roles"'::regclass
                 AND a.attnum > 0 AND NOT a.attisdropped
               ORDER BY a.attnum

   (0.3ms)  ROLLBACK
ActiveRecord::StatementInvalid: PG::UndefinedTable: ERROR:  relation "events_roles" does not exist
LINE 5:                WHERE a.attrelid = '"events_roles"'::regclass
                                          ^
:               SELECT a.attname, format_type(a.atttypid, a.atttypmod),
                     pg_get_expr(d.adbin, d.adrelid), a.attnotnull, a.atttypid, a.atttypmod
                FROM pg_attribute a LEFT JOIN pg_attrdef d
                  ON a.attrelid = d.adrelid AND a.attnum = d.adnum
               WHERE a.attrelid = '"events_roles"'::regclass
                 AND a.attnum > 0 AND NOT a.attisdropped
               ORDER BY a.attnum

It appears to be looking for an "events_roles" table and I don't understand why.

(events_users makes sense, but events_roles is out of the blue)

Help is appreciated.

Answer 1

This will be related to the 'rolify' you have in your Event class.

class Event < ActiveRecord::Base
  rolify
  ...

This is the Rolify gem, which probably generates extra tables/fields in the DB.