Using multiple PostgreSQL schemas with Rails models

72
votes

I have a PostgreSQL database for my Rails application. In the schema named 'public' the main Rails models tables are stored etc. I have created a 'discogs' schema which will have tables with names that are sometimes the same as in the 'public' schema - which is one of the reasons that I'm using schemas to organize this.

How would I setup models from the 'discogs' schema in my app? I will be using Sunspot to let Solr index these models as well. I'm unsure of how you would do this.

6
ruby-on-railspostgresqlmodelsdatabase-schemaschema-design
How does one create the non 'public' schema when setting up the database through the db:create rake task? Adding the schema to the template1 database is a possibility. But is there a way to do it as part of the normal rails/rake development process? - TsenYing
@TsenYing There is pg_power gem for that as one option. Its home is here. It hasn't been updated for 2 yrs though. Another option might be to write create rake task in db namespace and add your stuff there. - mlt

6 Answers

111
votes

PostgreSQL adapter schema_search_path in database.yml does solve your problem?

development:
  adapter: postgresql
  encoding: utf-8
  database: solidus
  host: 127.0.0.1
  port: 5432
  username: postgres
  password: postgres
  schema_search_path: "discogs,public"

Or, you can to specify different connections for each schema:

public_schema:
  adapter: postgresql
  encoding: utf-8
  database: solidus
  host: 127.0.0.1
  port: 5432
  username: postgres
  password: postgres
  schema_search_path: "public"

discogs_schema:
  adapter: postgresql
  encoding: utf-8
  database: solidus
  host: 127.0.0.1
  port: 5432
  username: postgres
  password: postgres
  schema_search_path: "discogs"

After each connection defined, create two models:

class PublicSchema < ActiveRecord::Base
  self.abstract_class = true
  establish_connection :public_schema
end

class DiscoGsSchema < ActiveRecord::Base
  self.abstract_class = true
  establish_connection :discogs_schema
end

And, all your models inherit from the respective schema:

class MyModelFromPublic < PublicSchema
  set_table_name :my_table_name
end

class MyOtherModelFromDiscoGs < DiscoGsSchema
  set_table_name :disco
end

I hope it helps.

16
votes

The correct one for rails 4.2 is as:

class Foo < ActiveRecord::Base
  self.table_name = 'myschema.foo'
end

More info -http://api.rubyonrails.org/classes/ActiveRecord/ModelSchema/ClassMethods.html#method-i-table_name-3D

12
votes

In migrations:

class CreateUsers < ActiveRecord::Migration
  def up
    execute 'CREATE SCHEMA settings'
    create_table 'settings.users' do |t|
      t.string :username
      t.string :email
      t.string :password

      t.timestamps null: false
    end
  end

  def down
    drop_table 'settings.users'
    execute 'DROP SCHEMA settings'
  end

end

Optional in model

class User < ActiveRecord::Base
  self.table_name 'settings.users'
end
11
votes

Because set_table_name was removed, and it was replaced by self.table_name.

I think you should code follow as:

class Foo < ActiveRecord::Base
  self.table_name =  'myschema.foo'
end
11
votes

Just do 

class Foo < ActiveRecord::Base
  self.table_name = 'myschema.foo'
end
3
votes

method set_table_name has been remove. self.table_name works fine.