Heroku: database configuration does not specify adapter - ruby

Question

I have an app deployed in heroku that uses postgresql as database. I have created a new model that will connect to a remote mysql database like the following:
# other_database.rb(apps/models/)
class OtherDatabase < ActiveRecord::Base
self.abstract_class = true
establish_connection "remote_#{Rails.env}"
end
# other_model.rb(apps/models/)
class OtherModel < OtherDatabase
self.table_name = "users"
end
i have also edited the database.yml file and added these entries:
remote_development:
adapter: mysql2
encoding: utf8
reconnect: false
database: app_development
pool: 5
username: root
password:
socket: /var/run/mysqld/mysqld.sock
remote_production:
adapter: mysql2
encoding: utf8
reconnect: true
database: app_production
pool: 40
username: root
password: secretpassword
socket: /var/run/mysqld/mysqld.sock
host: 12.34.56.78
The remote database uses mysql as its database.
It works fine in my local machine, but when I deploy it to heroku, it creates an error page so I looked up on the heroku logs, and I found this one out:
/app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.0.beta1/lib/active_record/connection_adapters/connection_specification.rb:52:in `resolve_hash_connection': database configuration does not specify adapter (ActiveRecord::AdapterNotSpecified)
from /app/vendor/bundle/ruby/2.0.0/gems/activerecord-4.0.0.beta1/lib/active_record/connection_adapters/connection_specification.rb:46:in `resolve_string_connection'
I am spent almost all my time searching for some answers but to no avail. Hope anyone can help out with this issue.
TIA.
Eralph

Answer 1

Heroku deletes and recreates the database.yml file. This means that what ever you put in your database.yml file will be totally ignored by heroku.
Pop your db credentials in your establish_connection method call like so:
establish_connection(
adapter: 'mysql2',
encoding: 'utf8',
reconnect: true,
database: 'app_production',
pool: 40,
username: 'root',
password: 'secretpassword',
socket: '/var/run/mysqld/mysqld.sock',
host: '12.34.56.78'
)
However it would be better to use a database URL and store it in an environment variable in heroku.
heroku config:set MYSQL_DB_URL=http://example.com/rest_of_the_url
then use
establish_connection(ENV['MYSQL_DB_URL'])
Example and docs for a url can be found here: http://forums.mysql.com/read.php?39,10734,10750