Neo4j <=> RubyOnRails ::: example code for migrating functionality to java || how to pass the live embedded database handle down to java || as used in wikibrains || this example assumes the use of neo4j.rb

java_service_controller.rb

#this example uses the javable functionality you may find @ https://gist.github.com/giladmanor/7972127
require 'javable'

#example controller using a service from java to access the neo4j database
class JavaServiceController < ActionController::Base
  include Javable
  require_jar_folder
  
  def get_some_graph_data
    j_service = javable("com.wikibrains.core.SomeService")
    
    #note the passing of the embedded database instance from rhe ruby layer over to java
    # namely: Neo4j.started_db translates in java to: GraphDatabaseService
    render :json => j_service.loveMeSomeData(Neo4j.started_db,params[:ids]).to_a.map{|i| [i.key, i.value]}
  end
  
end
  
  

SomeService.java

// Java stateless service that extracts and orders a list of nodes

public class SomeService {
  
  // this would be an example implementation of a service that retrieves a given list of nodes by one property (i.e. name)
  // and ordering the list by another property (i.e. value) and returns it with the highest value first
  public static List loveMeSomeData(GraphDatabaseService service, String[] nodeNames) {
    //grabbing the nodes by the list of names
    HashMap<String, Integer> list = new HashMap<>();
    for (String name : nodeNames) {
      // not that is requires that you have an index called "Clue_exact". 
      //and you dont, so then either use node id's or use what you have instead
      clue = service.index().forNodes("Clue_exact").get("name", name).getSingle();
      list.put(clue.getProperty("name").toString(), Integer.valueOf(clue.getProperty("value")));
    }
    
    //Sorting by value (No Brainer)
    ArrayList<Map.Entry<String, Integer>> l = new ArrayList(list.entrySet());
    Collections.sort(l, new Comparator<Map.Entry<?, Integer>>() {
      @Override
      public int compare(Map.Entry<?, Integer> o1, Map.Entry<?, Integer> o2) {
        return o2.getValue().compareTo(o1.getValue());
      }
    });
    return l;
  }
}