Merge pull request #181 from identity-research-lab/codes-leaking-from…

…-categories

Refactor Persona destroy as mechanism for reaping orphans

app/models/code.rb

@@ -23,6 +23,15 @@ def self.histogram(context)
     codes.inject({}) {|accumulator,code| accumulator[code.values[0]] ||= 0; accumulator[code.values[0]] += code.values[1]; accumulator}
   end
 
+  def self.orphans
+    query_as(:c).with('c, count{(c)-[:EXPERIENCES]-(:Persona)} AS ct').where('ct = 0').return('c, ct').map(&:first)
+  end
+
+  def self.reap_orphans
+    orphans = query_as(:c).with('c, count{(c)-[:EXPERIENCES]-(:Persona)} AS ct').where('ct = 0').return('c, ct').map(&:first)
+    orphans.each(&:destroy)
+  end
+
   private
 
   def sanitize

app/models/identity.rb

@@ -19,6 +19,15 @@ def self.histogram(context)
     identities.inject({}) {|accumulator,identity| accumulator[identity.values[0]] ||= 0; accumulator[identity.values[0]] += identity.values[1]; accumulator}
   end
 
+  def self.orphans
+    query_as(:i).with('i, count{(i)-[:IDENTIFIES_WITH]-(:Persona)} AS ct').where('ct = 0').return('i, ct').map(&:first)
+  end
+
+  def self.reap_orphans
+    orphans = query_as(:i).with('i, count{(i)-[:IDENTIFIES_WITH]-(:Persona)} AS ct').where('ct = 0').return('i, ct').map(&:first)
+    orphans.each(&:destroy)
+  end
+
   private
 
   def strip_whitespace

app/models/services/export_to_graph.rb

@@ -16,8 +16,6 @@ def initialize(case_id)
 		def perform
 			return false unless kase
 
-			# Destroy the existing persona so that neo4j will reap orphaned nodes like Codes and Identities.
-			Persona.find_or_initialize_by(case_id: kase.id).destroy
 			populate_codes
 			populate_identities
 			return true
@@ -41,6 +39,7 @@ def populate_codes
 				next if question.is_identity?
 
 				context = question.context.name
+				persona.codes = []
 
 				response.raw_codes.compact.uniq.each do |name|
 					if code = Code.find_or_create_by(name: name, context: context)
@@ -49,6 +48,9 @@ def populate_codes
 					end
 				end
 			end
+
+			# Clean up any Codes that are no longer associated with a Persona.
+			Code.reap_orphans
 		end
 
 		# Creates Identity nodes and connects them to the associated Persona.
@@ -58,6 +60,7 @@ def populate_identities
 				next unless question.is_identity?
 
 				context = question.context.name
+				persona.identities = []
 
 				response.raw_codes.compact.uniq.each do |name|
 					if identity = Identity.find_or_create_by(name: name.strip, context: context)
@@ -66,6 +69,9 @@ def populate_identities
 					end
 				end
 			end
+
+			# Clean up any Identities that are no longer associated with a Persona.
+			Identity.reap_orphans
 		end
 
 	end

spec/models/services/export_to_graph_spec.rb

@@ -8,10 +8,12 @@
 
 		allow(Persona).to receive(:find_or_create_by).and_return(persona)
 		allow(Persona).to receive(:find_or_initialize_by).and_return(persona)
-		allow(persona).to receive(:destroy)
 
 		allow(Identity).to receive(:find_or_create_by).and_return(identity)
+		allow(Identity).to receive(:reap_orphans)
+
 		allow(Code).to receive(:find_or_create_by).and_return(code)
+		allow(Code).to receive(:reap_orphans)
 
 		allow(response_1).to receive(:question).and_return(question_1)
 		allow(response_2).to receive(:question).and_return(question_2)