Sample configuration:
---------------------

config/database.yml

development:
  adapter: neo4j_rest
  host: localhost
  port: 7474

Check connection:
-----------------
$ rails c
Loading development environment (Rails 3.0.9)
irb(main):001:0> c = ActiveRecord::Base.connection
irb(main):002:0> c.neo_server.list_node_indexes
=> {"model_index"=>{"type"=>"exact", "template"=>"http://localhost:7474/db/data/index/node/model_index/{key}/{value}", "provider"=>"lucene"}}

For applications using multiple databases:
------------------------------------------

config/database.yml

development:
  adapter: mysql2
  host: localhost
  user: mysql
  password: mysql

graph_development:
  adapter: neo4j_rest
  host: localhost
  port: 7474

Some regular model:

class AdapterTest < ActiveRecord::Base

...

end

Model using neo4j_rest adapter (add establish_connection to corresponding entry in database.yml):

class AdapterTest < ActiveRecord::Base
  establish_connection "graph_#{Rails.env}"

  ...

end

In case the primary connection is non-neo4j_rest, migrations need to be modified a bit.

Sample migration:

class CreateAdapterTests < ActiveRecord::HybridDatabaseConnector::Migration
  connection_for AdapterTest

  def self.up
    create_table :adapter_tests, :class_name => AdapterTest.to_s do |t|
      t.timestamps
    end
  end

  def self.down
    drop_table :adapter_tests
  end
end

  - connection_for takes a class which could guide ActiveRecord::Migrator to use a neo4j_rest connection. In the above case, AdapterTest has an establish_connection with neo4j_rest adapter, hence "connection_for AdapterTest"
  - :class_name option in create_table ensures that model class name is stored on model super node. This would enable graph relationships across heterogenous data types.

Instantiating a model object from Graph
---------------------------------------
# Get a node with id 48
node = AdapterTest.connection.execute_gremlin 'g.v(48)'

adapter_instance = AdapterTest.load_from_graph node

# load_from_graph would accept a node hash or an array of hashes

Most AREL syntaxes shall work:
------------------------------

AdapterTest.select(:name).where(:id => [1,2,3,4])
AdapterTest.create(:name => 'Neo')
AdapterTest.where(:name => 'Neo').update_all :alias => 'Anderson'
AdapterTest.where(:name => 'Neo').destroy_all