Sinatra, Mongoid, Heroku, MongoHQ: connecting to Mongodb - ruby

Question

Trying to get Mongoid up and running with Sinatra on Heroku (MongoHQ). Previous experience with Rails but first time with the stack and Sinatra.
Started with one of the simple examples on the web (app.rb):
require 'rubygems'
require 'sinatra'
require 'mongo'
require 'mongoid'
configure do
Mongoid.load!('mongoid.yml')
Mongoid.configure do |config|
if ENV['MONGOHQ_URL']
conn = Mongo::Connection.from_uri(ENV['MONGOHQ_URL'])
uri = URI.parse(ENV['MONGOHQ_URL'])
# problem happens here
config.master = conn.db(uri.path.gsub(/^\//, ''))
else
config.master = Mongo::Connection.from_uri("mongodb://localhost:27017").db('test')
end
end
end
# Models
class Counter
include Mongoid::Document
field :count, :type => Integer
def self.increment
c = first || new({:count => 0})
c.inc(:count, 1)
c.save
c.count
end
end
# Controllers
get '/' do
"Hello visitor n" + Counter.increment.to_s
end
For reference, mongoid.yml looks like:
development:
sessions:
default:
database: localhost
production:
sessions:
default:
uri: <%= ENV['MONGOHQ_URL'] %>
As per app.rb (# problem happens here), my logs say:
/app/app.rb:15:in `block (2 levels) in <top (required)>': undefined method `master=' for Mongoid::Config:Module (NoMethodError)
from /app/vendor/bundle/ruby/1.9.1/gems/mongoid-3.0.3/lib/mongoid.rb:112:in `configure'
from /app/app.rb:11:in `block in <top (required)>'
from /app/vendor/bundle/ruby/1.9.1/gems/sinatra-1.3.2/lib/sinatra/base.rb:1273:in `configure'
from /app/app.rb:8:in `<top (required)>'
I have also tried variants, including:
config.master = Mongo::Connection.from_uri(ENV['MONGOHQ_URL']).db('appXXXXX')
Mongoid.database = Mongo::Connection.from_uri(ENV['MONGOHQ_URL']).db('appXXXXXXX')
But get the same error:
undefined method `master` for Mongoid::Config:Module (NoMethodError)
or:
undefined method `database=` for Mongoid::Config:Module (NoMethodError)
What am I missing?

Answer 1

Shouldn't be
configure do
Mongoid.load!('mongoid.yml')
end
enough?
That's what the mongid docs are saying. The MONGOHQ_URL environment variable already contains every information to initialize the connection to the db.

Answer 2

So was using Mongoid 3.x ... which:
Doesn't use 10gen driver: uses Moped
Doesn't use config.master
The canonical sample code above which is all over the web works out of the box with Mongoid 2.x so have dropped back to that for the time being.
Thanks!