Rails separate DB migration not working - ruby-on-rails

Question

I am trying to run a migration to a separate DB in Rails, using establish_connection. I have something like this in the migration file:
def change
ActiveRecord::Base.establish_connection("user_#{Rails.env}")
ActiveRecord::Base.initialize_schema_migrations_table
create_table "users", :force => true do |t|
t.string "email",
end
In the yml I have this config:
user_development:
adapter: postgresql
encoding: unicode
database: MyApp_user_development
pool: 5
host: localhost
username: xxx
password: xxx
Also I have defined the User Model like this:
class User < ActiveRecord::Base
establish_connection "user_#{Rails.env}"
[...]
end
Now, the DB exists but when running rake db:migrate I get this error:
== CreateUserOnSeparateDb: migrating =========================================
rake aborted!
An error has occurred, this and all later migrations canceled:
connection is closed
Does any of you have any idea what is going on?
I have also tried to move the establish_connection call into a connection method in the migration file. In this case the table is created on migrate but then I get the same error (so somehow failing on other migrations) and by the way it does not create the schema_migrations table...
Any help?

Answer 1

Resolved above issue by following below steps.
class AddCustomTbl < ActiveRecord::Migration
def connection
ActiveRecord::Base.establish_connection(Rails.env).connection
end
def up
# Connection with user_#{Rails.env}
oldEnv = Rails.env
Rails.env = "user_#{Rails.env}"
ActiveRecord::Base.establish_connection(Rails.env)
create_table "users", :force => true do |t|
t.string "email"
end
# Connection with Rails.env
Rails.env = oldEnv
ActiveRecord::Base.establish_connection ActiveRecord::Base.configurations[Rails.env]
end
def down
# Connection with user_#{Rails.env}
oldEnv = Rails.env
Rails.env = "user_#{Rails.env}"
ActiveRecord::Base.establish_connection(Rails.env).connection
drop_table :users
# Connection with Rails.env
Rails.env = oldEnv
ActiveRecord::Base.establish_connection ActiveRecord::Base.configurations[Rails.env]
end
end