Lazy evaluation of ActiveRecord::Relation.

1 files changed, 13 insertions, 3 deletions

diff --git a/app/models/message.rb b/app/models/message.rb
index 742a9c1..ee267c6 100644
--- a/app/models/message.rb
+++ b/app/models/message.rb
@@ -81,13 +81,22 @@ class Message < ActiveRecord::Base
     transaction do
       create_update_helper(request, app_namespace, ressource_name, participant.id)
       save!
-      receivers_old = Participant.for_message(self).uniq
+      # NOTE Unit test doesn't pass if we are not explicitely accessing
+      # the ActiveRecord::Relation receivers_old and receivers_new, beacause
+      # of Rails's "lazy evaluation".
+      # ("MessageTest#test_update_receivers [/home/mb7/freelancer/projekte/ecs4/test/models/message_test.rb:56]")
+      # With accessing the ActiveRecord::Relation with #to_a we force an evaluation
+      # by converting ActiveRecord::Relation to an array of Model-Objects. We could 
+      # have done this # also by calling #load!, but would have get back still an
+      # ActiveRecord::Relation, which works also.
+      receivers_old = Participant.for_message(self).uniq.to_a
+      #puts "*** receivers_old: #{receivers_old.inspect}"
       MembershipMessage.de_populate_jointable(self)
       MembershipMessage.populate_jointable(self,
                                            request.headers["X-EcsReceiverMemberships"],
                                            request.headers["X-EcsReceiverCommunities"],
                                            participant)
-      receivers_new = Participant.for_message(self).uniq
+      receivers_new = Participant.for_message(self).uniq.to_a
       # TODO: if there are only the headers X-EcsReceiverMemberships and
       # X-EcsReceiverCommunities are updated, then we have to generate events only
       # for these new and removed receivers. To distinguish if the message body
@@ -127,7 +136,8 @@ class Message < ActiveRecord::Base
 
   # return first messages from fifo/lifo queue
   def self.fifo_lifo_rest(namespace, ressource, participant_id, options={:queue_type => :fifo})
-    m = all.readonly(false).select(:id).
+    m = all.
+        readonly(false).
         joins(:ressource, :membership_messages => { :membership => :participant }).
         where(:participants => { :id => participant_id },
               :ressources => { :namespace => namespace, :ressource => ressource }).