Update associations on object delete

Resolves issue #467

Author: kkan

lib/dynamoid/associations/association.rb

@@ -58,6 +58,12 @@ def declaration_field_type
         :set
       end
 
+      def disassociate_source
+        Array(target).each do |target_entry|
+          target_entry.send(target_association).disassociate(source.hash_key) if target_entry && target_association
+        end
+      end
+
       private
 
       # The target class name, either inferred through the association's name or specified in options.

lib/dynamoid/associations/single_association.rb

@@ -28,7 +28,7 @@ def setter(object)
       # unsaved changes will be saved. Doesn't delete an associated model from
       # DynamoDB.
       def delete
-        target.send(target_association).disassociate(source.hash_key) if target && target_association
+        disassociate_source
         disassociate
         target
       end
@@ -90,7 +90,7 @@ def empty?
 
       # @private
       def associate(hash_key)
-        target.send(target_association).disassociate(source.hash_key) if target && target_association
+        disassociate_source
         source.update_attribute(source_attribute, Set[hash_key])
       end
 

lib/dynamoid/persistence.rb

@@ -801,9 +801,20 @@ def delete
 
       @destroyed = true
 
-      Dynamoid.adapter.delete(self.class.table_name, hash_key, options)
+      Dynamoid.adapter.delete(self.class.table_name, hash_key, options).tap { update_asociations }
     rescue Dynamoid::Errors::ConditionalCheckFailedException
       raise Dynamoid::Errors::StaleObjectError.new(self, 'delete')
     end
+
+    private
+
+    def update_asociations
+      self.class.associations.each do |name, options|
+        begin
+          send(name).disassociate_source
+        rescue Aws::DynamoDB::Errors::ResourceNotFoundException
+        end
+      end
+    end
   end
 end

spec/dynamoid/persistence_spec.rb

@@ -2597,6 +2597,38 @@ def log_message
         expect { a1.destroy }.to_not raise_error
       end
     end
+
+    context 'with associations' do
+      let!(:user) { User.create }
+      let!(:camel_case) { user.camel_case.create }
+      let!(:magazine) { user.books.create }
+      let!(:monthly) { user.monthly.create }
+      let!(:subscription) { user.subscriptions.create }
+
+      it 'updates belongs_to association' do
+        expect do
+          user.delete
+        end.to change { CamelCase.find(camel_case.id).users.target }.from([user]).to([])
+      end
+
+      it 'updates has_many association' do
+        expect do
+          user.delete
+        end.to change { Magazine.find(magazine.title).owner.target }.from(user).to(nil)
+      end
+
+      it 'updates has_one association' do
+        expect do
+          user.delete
+        end.to change { Subscription.find(monthly.id).customer.target }.from(user).to(nil)
+      end
+
+      it 'updates has_and_belongs_to_many association' do
+        expect do
+          user.delete
+        end.to change { Subscription.find(subscription.id).users.target }.from([user]).to([])
+      end
+    end
   end
 
   describe '.import' do