How to Use Multiple Databases in a Rails App Using the database.yml

Question

I've read up on the documentation on how to do this, but in practice, I am having problems. In my app, I have 2 different databases as described below in my database.yml file.

sqlite_test:
    adapter: sqlite3
    database: db/sqlite_test.sqlite3
    table: plots
    pool: 5
    timeout: 5000

development:
  adapter: mysql2
  encoding: utf8
  reconnect: false
  database: test
  pool: 5
  username: myname
  password: mypassword
  host: localhost

My application is a dynamic plotter that will plot the data in a (basic) database without having knowledge of whats in the database, or how its structured. Both of these databases contain different data. The SQLite database I created in a separate Rails app.

The current app I'm using is built around the MYSQL database, which I build externally. I copied the SQLite database into the /db directory. So in my main model, when I say:

  class Plot < ActiveRecord::Base

  establish_connection :development
  set_table_name "stock_test"
  set_primary_key :id

Everything works out just fine and dandy. However, when I change it to:

 establish_connection :sqlite_test
 set_table_name "plots"

and try to access that database via the Rails console, I get an error saying:

>>ActiveRecord::AdapterNotSpecified: database configuration does not specify adapter

I don't know why that is, since the database.yml file clearly does specify an adapter? When I do it by hand in my model though, everything works exactly as it should.

class Plot < ActiveRecord::Base
establish_connection(:adapter => "sqlite3", :database => "db/sqlite_test.sqlite3", :pool => 5 )

Why does it all work when I manually specify whats in the database.yml, but not when I just use the database.yml reference?

Thanks!

Answer 1

I tried to replicate and got it to work. It has to do with naming conventions: You're in development mode and AR will look for the development tag, which in your case does not exist for sqlite.

Here is my database.yml:

development:
  adapter: mysql2
  database: se_development
  username: root
  pool: 5
  timeout: 5000

sqlite_development:
  adapter: sqlite3
  database: db/development.sqlite3
  pool: 5
  timeout: 5000

Here is the model:

class Plot < ActiveRecord::Base
  establish_connection 'sqlite_' + Rails.env
end

Worked for me. Hope this helps.