#389 Multitenancy with PostgreSQL pro

rails db
rails g model tenant subdomain
rake db:migrate
rails c
rails g migration add_sticky_to_topics sticky:boolean
rails g migration add_name_to_tenants name

t = Tenant.create! subdomain: "cheese"
c = t.connection
c.execute("create schema tenant1")
c.schema_search_path = "tenant1"
load 'db/schema.rb'
Post.all
Tenant.all
c.execute("drop table tenants")
c.schema_search_path = "tenant1, public"
Tenant.all
Post.all
Tenant.create! subdomain: "chunkybacon"

\dt
\dn
create schema foo;
create table foo.items ();
delete from items
delete from foo.items
show search_path;
set search_path to foo, public;
delete from items
drop schema foo cascade

after_create :create_schema

def create_schema
  connection.execute("create schema tenant#{id}")
  scope_schema do
    load Rails.root.join("db/schema.rb")
    connection.execute("drop table #{self.class.table_name}")
  end
end

def scope_schema(*paths)
  original_search_path = connection.schema_search_path
  connection.schema_search_path = ["tenant#{id}", *paths].join(",")
  yield
ensure
  connection.schema_search_path = original_search_path
end

around_filter :scope_current_tenant

private

def current_tenant
  @current_tenant ||= Tenant.find_by_subdomain!(request.subdomain)
end
helper_method :current_tenant

def scope_current_tenant(&block)
  current_tenant.scope_schema("public", &block)
end

<h1><%= current_tenant.name %> Forum</h1>

db_tasks = %w[db:migrate db:migrate:up db:migrate:down db:rollback db:forward]

namespace :multitenant do
  db_tasks.each do |task_name|
    desc "Run #{task_name} for each tenant"
    task task_name => %w[environment db:load_config] do
      Tenant.find_each do |tenant|
        puts "Running #{task_name} for tenant#{tenant.id} (#{tenant.subdomain})"
        tenant.scope_schema { Rake::Task[task_name].execute }
      end
    end
  end
end

db_tasks.each do |task_name|
  Rake::Task[task_name].enhance(["multitenant:#{task_name}"])
end