Ruby on Rails连接到正确的Postgres DB

Question

I have developed a website using RoR + Postgresql, migrated it to Heroku using Git. All works well.

Then I imported the website and the databases from Heroku back to local (on another computer). All went well too.

However, I now have 4 databases locally:

myapp myapp_test myapp_development myapp_production

When testing my app locally, it turns out it is communicating with myapp_development.

But all my data is in the DB myapp .

How do I instruct RoR to use the DB myapp ?

Answer 1

If I understand you correct - I can provide next solution. Here is example of config/database.yml

login: &login
  adapter: postgresql
  encoding: utf8
  host: localhost
  username: user_name
  password: password

development:
  <<: *login
  database: db_name_development

test:
  <<: *login
  database: db_name_test

production:
  <<: *login
  database: db_name_production

Try to replace:

development:
  <<: *login
  database: db_name_development

With:

development:
  <<: *login
  database: myapp_development

I hope it will help you.

Answer 2

Rails uses database configuration from two sources - ENV['DATABASE_URL'] and config/database.yml .

ENV['DATABASE_URL'] is an env var that is set in the shell, operating system or when involking the process.

For an example setting ENV['DATABASE_URL'] to:

postgresql://localhost/myapp

Would connect to the correct database via postgres. This is how Heroku sets which database your production app connects to.

config/database.yml is just a YAML file that is read by ActiveRecord when setting up the database. It contains a hash of hashes - which key is used is determined by Rails.env (which is set via ENV['RAILS_ENV'] ).

common: &common
  adapter: postgresql
  encoding: utf8
  host: localhost

development:
  <<: *common # this is YAML syntax to merge this hash with &common
  database: myapp

The values in ENV['DATABASE_URL'] are merged with those from config/database.yml but ENV['DATABASE_URL'] has preceedence.

A friendly tip:

• Just set the bare minimum in config/database.yml - everything such as usernames, passwords etc should be set via ENV['DATABASE_URL'] for security reasons and to avoid developer wars.