Création d'une application multi-locataires utilisant les schémas et les Rails de PostgreSQL

Mettre À Jour Le 5 Décembre 2011

grâce à Brad Robertson et son équipe, il y a le Appartement gem . Il est très utile et fait beaucoup de levage lourd.

cependant, si vous devez bricoler des schémas, je suggère fortement de savoir comment cela fonctionne réellement. Familiarisez-vous avec Jerod Santo's walkthrough , de sorte que vous saurez ce que le joyau de L'appartement est plus ou moins de faire.

Update Aug 20, 2011 11: 23 GMT+8

Quelqu'un a créé un blog post et marche à travers tout ce processus assez bien.

Update May 11, 2010 11:26 GMT+8

depuis hier soir, j'ai pu obtenir une méthode de travail qui crée un nouveau schéma et charge le schéma.rb. Je ne sais pas si ce que je fais est correct (semble fonctionner bien, jusqu'à présent), mais c'est une étape de plus au moins. S'il y a un meilleur moyen, dites-le-moi.

  module SchemaUtils
   def self.add_schema_to_path(schema)
    conn = ActiveRecord::Base.connection
    conn.execute "SET search_path TO #{schema}, #{conn.schema_search_path}"
   end

   def self.reset_search_path
    conn = ActiveRecord::Base.connection
    conn.execute "SET search_path TO #{conn.schema_search_path}"
   end

   def self.create_and_migrate_schema(schema_name)
    conn = ActiveRecord::Base.connection

    schemas = conn.select_values("select * from pg_namespace where nspname != 'information_schema' AND nspname NOT LIKE 'pg%'")

    if schemas.include?(schema_name)
     tables = conn.tables
     Rails.logger.info "#{schema_name} exists already with these tables #{tables.inspect}"
    else
     Rails.logger.info "About to create #{schema_name}"
     conn.execute "create schema #{schema_name}"
    end

    # Save the old search path so we can set it back at the end of this method
    old_search_path = conn.schema_search_path

    # Tried to set the search path like in the methods above (from Guy Naor)
    # [METHOD 1]: conn.execute "SET search_path TO #{schema_name}"
    # But the connection itself seems to remember the old search path.
    # When Rails executes a schema it first asks if the table it will load in already exists and if :force => true. 
    # If both true, it will drop the table and then load it. 
    # The problem is that in the METHOD 1 way of setting things, ActiveRecord::Base.connection.schema_search_path still returns $user,public.
    # That means that when Rails tries to load the schema, and asks if the tables exist, it searches for these tables in the public schema.
    # See line 655 in Rails 2.3.5 activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
    # That's why I kept running into this error of the table existing when it didn't (in the newly created schema).
    # If used this way [METHOD 2], it works. ActiveRecord::Base.connection.schema_search_path returns the string we pass it.
    conn.schema_search_path = schema_name

    # Directly from databases.rake. 
    # In Rails 2.3.5 databases.rake can be found in railties/lib/tasks/databases.rake
    file = "#{Rails.root}/db/schema.rb"
    if File.exists?(file)
     Rails.logger.info "About to load the schema #{file}"
     load(file)
    else
     abort %{#{file} doesn't exist yet. It's possible that you just ran a migration!}
    end

    Rails.logger.info "About to set search path back to #{old_search_path}."
    conn.schema_search_path = old_search_path
   end
  end