CODEWITHSUNDEEP
ruby-on-railsruby
Sudeep Kaushik
Sudeep Kaushik

Reputation: 79

Setting options for create_join_table migration in Rails

I have some issues. I'm new to RoR

I'm trying to create a join table using Rails migration. Documentation of this is here... http://api.rubyonrails.org/classes/ActiveRecord/ConnectionAdapters/SchemaStatements.html#method-i-create_join_table

When I do... 

rails g migration CreateJoinTableUserOffer users offers

...it creates the following migration 

class CreateJoinTableUserOffer < ActiveRecord::Migration
 def change
   create_join_table:users, :offers  do |t|
         t.index [:user_id, :offer_id]
         t.index [:offer_id, :user_id]
      end       
    end
   end

and when I do...

rake db:migrate

it creates...

-- Table: offers_users

-- DROP TABLE offers_users;

CREATE TABLE offers_users
(
 user_id integer NOT NULL,
 offer_id integer NOT NULL
)
WITH (



OIDS=FALSE
);
ALTER TABLE offers_users
 OWNER TO sudeepkaushik;

-- Index: index_offers_users_on_offer_id_and_user_id

-- DROP INDEX index_offers_users_on_offer_id_and_user_id;

CREATE INDEX index_offers_users_on_offer_id_and_user_id
 ON offers_users
 USING btree
 (offer_id, user_id);

-- Index: index_offers_users_on_user_id_and_offer_id

-- DROP INDEX index_offers_users_on_user_id_and_offer_id;

CREATE INDEX index_offers_users_on_user_id_and_offer_id
 ON offers_users
 USING btree
 (user_id, offer_id);

What I want to do is that I first of all want the table name to be users_offers instead of offers_users, for this you can specify the :table_name in the create_join_table migration. I'm not able to get the syntax of setting this option correctly. Need help here!

2nd, I noticed that this migration doesn't create the foreign keys that I would expect with the Users and Offers tables. Need your comments here also. Do I need to manually create the foreign keys myself?

Upvotes: 4

Views: 3083

Answers (1)

Robin
Robin

Reputation: 8498

You can define your join tables name with the table_name option.

create_join_table :users, :offers, table_name: :users_offers

There is also an option for setting column options called column_options, but I only got it to work for indexes and not for foreign keys.

create_join_table :users, :offers, column_options: { index: true }

This will create the desired indexes, but it ignores foreign_key: true. So you need to create them separately.

add_foreign_key :users_offers, :users
add_foreign_key :users_offers, :offers

In your models you need to add the relation like this:

# user.rb
has_and_belongs_to_many :offers, join_table: :users_offers

And:

# offers.rb
has_and_belongs_to_many :users, join_table: :users_offers

Upvotes: 9

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