Allow embedded arrays to properly get updated atomically. Fixes #1593

CHANGELOG.md

@@ -47,6 +47,9 @@ For instructions on upgrading to newer versions, visit
 
 ### Resolved Issues
 
+* \#1593 Arrays on embedded documents now properly atomically update when
+  modified from original version.
+
 * \#1592 Don't swallow exceptions from index generation in the create_indexes
   rake task.
 

lib/mongoid/dirty.rb

@@ -131,7 +131,14 @@ def setters
             field = fields[name]
             key = embedded? ? "#{atomic_position}.#{name}" : name
             if field && field.resizable?
-              field.add_atomic_changes(self, key, modifications, new, old)
+              field.add_atomic_changes(
+                self,
+                name,
+                key,
+                modifications,
+                new,
+                old
+              )
             else
               modifications[key] = new
             end

lib/mongoid/fields/internal/array.rb

@@ -13,19 +13,20 @@ class Array
         #   field.add_atomic_changes(doc, "key", {}, [], [])
         #
         # @param [ Document ] document The document to add to.
-        # @param [ String ] key The name of the field.
+        # @param [ String ] name The name of the field.
+        # @param [ String ] key The atomic location of the field.
         # @param [ Hash ] mods The current modifications.
         # @param [ Array ] new The new elements to add.
         # @param [ Array ] old The old elements getting removed.
         #
         # @since 2.4.0
-        def add_atomic_changes(document, key, mods, new, old)
+        def add_atomic_changes(document, name, key, mods, new, old)
           pushes = (new || []) - (old || [])
           pulls = (old || []) - (new || [])
           if old.nil?
             mods[key] = pushes
           elsif !pushes.empty? && !pulls.empty?
-            mods[key] = document.attributes[key]
+            mods[key] = document.attributes[name]
           elsif !pushes.empty?
             document.atomic_array_pushes[key] = pushes
           elsif !pulls.empty?

lib/mongoid/fields/internal/foreign_keys/array.rb

@@ -14,19 +14,20 @@ class Array
           #   field.add_atomic_changes(doc, "key", {}, [], [])
           #
           # @param [ Document ] document The document to add to.
-          # @param [ String ] key The name of the field.
+          # @param [ String ] name The name of the field.
+          # @param [ String ] key The atomic location of the field.
           # @param [ Hash ] mods The current modifications.
           # @param [ Array ] new The new elements to add.
           # @param [ Array ] old The old elements getting removed.
           #
           # @since 2.4.0
-          def add_atomic_changes(document, key, mods, new, old)
+          def add_atomic_changes(document, name, key, mods, new, old)
             pushes = (new || []) - (old || [])
             pulls = (old || []) - (new || [])
             if old.nil?
               mods[key] = pushes
             elsif !pushes.empty? && !pulls.empty?
-              mods[key] = document.attributes[key]
+              mods[key] = document.attributes[name]
             elsif !pushes.empty?
               document.atomic_array_add_to_sets[key] = pushes
             elsif !pulls.empty?

spec/app/models/video.rb

@@ -3,6 +3,7 @@ class Video
   field :title, :type => String
   field :year, :type => Integer
   field :release_dates, :type => Set
+  field :genres, :type => Array
 
   embedded_in :person
   belongs_to :post

spec/functional/mongoid/relations/embedded/many_spec.rb

@@ -2686,4 +2686,58 @@
       end
     end
   end
+
+  context "when the embedded document has an array field" do
+
+    let!(:person) do
+      Person.create(:ssn => "673-11-2322")
+    end
+
+    let!(:video) do
+      person.videos.create
+    end
+
+    context "when saving the array on a persisted document" do
+
+      before do
+        video.genres = [ "horror", "scifi" ]
+        video.save
+      end
+
+      it "sets the value" do
+        video.genres.should eq([ "horror", "scifi" ])
+      end
+
+      it "persists the value" do
+        video.reload.genres.should eq([ "horror", "scifi" ])
+      end
+
+      context "when reloading the parent" do
+
+        let!(:loaded_person) do
+          Person.find(person.id)
+        end
+
+        let!(:loaded_video) do
+          loaded_person.videos.find(video.id)
+        end
+
+        context "when writing a new array value" do
+
+          before do
+            loaded_video.genres = [ "comedy" ]
+            loaded_video.save
+          end
+
+          it "sets the new value" do
+            loaded_video.genres.should eq([ "comedy" ])
+          end
+
+          it "persists the new value" do
+            loaded_video.reload.genres.should eq([ "comedy" ])
+          end
+        end
+      end
+    end
+  end
 end

spec/unit/mongoid/fields/internal/array_spec.rb

@@ -23,7 +23,7 @@
         before do
           person.aliases = [ "007", "008" ]
           field.add_atomic_changes(
-            person, "aliases", mods, [ "008" ], [ "009" ]
+            person, "aliases", "aliases", mods, [ "008" ], [ "009" ]
           )
         end
 
@@ -37,7 +37,7 @@
         before do
           person.aliases = [ "007", nil ]
           field.add_atomic_changes(
-            person, "aliases", mods, [ nil ], [ "008" ]
+            person, "aliases", "aliases", mods, [ nil ], [ "008" ]
           )
         end
 

spec/unit/mongoid/fields/internal/foreign_keys/array_spec.rb

@@ -42,7 +42,7 @@
 
       before do
         field.add_atomic_changes(
-          person, "preference_ids", mods, [ preference_three.id ], [ preference_two.id ]
+          person, "preference_ids", "preference_ids", mods, [ preference_three.id ], [ preference_two.id ]
         )
       end