Made it possible to use Related together with another database for st…

…oring node data. #1

README.md

@@ -382,6 +382,37 @@ relationships on the same machine, making set operations on relationships
 a lot faster overall. But with the obvious drawback that the total size of
 your graph will be limited by that single machine.
 
+Using Related with another database
+-----------------------------------
+
+Related can easily be used together with other databases than Redis to store
+Node data. Relationships are always stored in Redis, but node data can often
+have characteristics that make Redis unsuitable (like large size).
+
+You can for example use Related together with the Ripple gem to store nodes
+in Riak:
+
+```ruby
+class CustomNode
+  include Ripple::Document
+  include Related::Node::QueryMethods
+
+  def query
+    Related::Node::Query.new(self)
+  end
+end
+```
+
+You can then use the `CustomNode` class as an ordinary Related graph Node and
+query the graph like usual:
+
+```ruby
+node1 = CustomNode.create
+node2 = CustomNode.create
+Related::Relationship.create(:friend, node1, node2)
+node1.shortest_path_to(node2).outgoing(:friend)
+```
+
 Development
 -----------
 

lib/related/node.rb

@@ -113,7 +113,7 @@ def map(&block)
       def to_a
         perform_query unless @result
         if @result_type == :nodes
-          Related::Node.find(@result, @options)
+          node_class.find(@result, @options)
         else
           Related::Relationship.find(@result, @options)
         end
@@ -134,7 +134,7 @@ def include?(entity)
         if @destination
           self.to_a.include?(entity)
         else
-          if entity.is_a?(Related::Node)
+          if entity.is_a?(node_class)
             @result_type = :nodes
             Related.redis.sismember(key, entity.to_s)
           elsif entity.is_a?(Related::Relationship)
@@ -147,7 +147,7 @@ def include?(entity)
       def find(node)
         if @result_type == :nodes
           if Related.redis.sismember(key, node.to_s)
-            Related::Node.find(node.to_s, @options)
+            node_class.find(node.to_s, @options)
           end
         else
           if id = Related.redis.get(dir_key(node))
@@ -217,6 +217,10 @@ def to_json(options = {})
 
     protected
 
+      def node_class
+        @node.class
+      end
+
       def page_start
         if @page.nil? || @page.to_i.to_s == @page.to_s
           @page && @page.to_i != 1 ? (@page.to_i * @limit.to_i) - @limit.to_i : 0

test/custom_node_test.rb

@@ -0,0 +1,46 @@
+require File.expand_path('test/test_helper')
+require 'pp'
+
+class CustomNodeTest < ActiveModel::TestCase
+
+  class CustomNode
+    include Related::Node::QueryMethods
+    attr_accessor :id
+    def self.flush
+      @database = {}
+    end
+    def self.create
+      n = self.new
+      n.id = Related.generate_id
+      @database ||= {}
+      @database[n.id] = n
+      n
+    end
+    def self.find(*ids)
+      ids.pop if ids.size > 1 && ids.last.is_a?(Hash)
+      ids.flatten.map do |id|
+        @database[id]
+      end
+    end
+    def to_s
+      @id
+    end
+    protected
+      def query
+        Related::Node::Query.new(self)
+      end
+  end
+
+  def setup
+    Related.redis.flushall
+    CustomNode.flush
+  end
+
+  def test_property_conversion
+    node1 = CustomNode.create
+    node2 = CustomNode.create
+    Related::Relationship.create(:friend, node1, node2)
+    assert_equal [node2], node1.shortest_path_to(node2).outgoing(:friend).nodes.to_a
+  end
+
+end