I am developing Rails v2.3 app with MySQL database and mysql2 gem. I faced a weird situation which is about changing the environment in rake task.

(all my setting and configurations for environment and database are correct, no problem for that.)

Here is my simple story :

I have a rake task like following:

namespace :db do
   task :do_something => :environment do
       #1. run under 'development' environment
       my_helper.run_under_development_env

       #2. change to 'custom' environment 
       RAILS_ENV='custom'

       Rake::Task['db:create']
       Rake::Task['db:migrate']

       #3. change back to 'development' environment
       RAILS_ENV='development'

       #4. But it still run in 'customer' environment, why?
       my_helper.run_under_development_env 
   end

end

The rake task is quite simple, what it does is:

1. Firstly, run a method from my_helper under "development" environment

2. Then, change to "custom" environment and run db:create and db:migrate

until now, everything is fine, the environment did change to "custom"

3. Then, change it back again to "development" environment

4. run helper method again under "development" environment

But, though I have changed the environment back to "development" in step 3, the last method still run in "custom" environment, why? and how to get rid of it?

--- P.S. ---

I have also checked a post with the similar situation here, and tried to use the solution there like (in step 2):

ActiveRecord::Base.establish_connection('custom')
Rake::Task['db:create']
Rake::Task['db:migrate']

to change the database connection instead of changing environment but, the db:create and db:migrate will still run under "development" database, though the linked post said it should run for "custom" database... weird