MONGOID-5935 Fixed UnknownAttribute error with nested attributes (#6155)

Author: jamis

lib/mongoid/association/nested/many.rb

@@ -192,12 +192,14 @@ def update_nested_relation(parent, id, attrs)
           elsif association.embedded?
             raise Errors::DocumentNotFound.new(association.klass, id)
           elsif association.is_a?(Association::Referenced::HasAndBelongsToMany) || Mongoid.allow_reparenting_via_nested_attributes?
-            Mongoid::Warnings.warn_reparenting_via_nested_attributes if Mongoid.allow_reparenting_via_nested_attributes?
+            unless destroyable?(attrs)
+              Mongoid::Warnings.warn_reparenting_via_nested_attributes if Mongoid.allow_reparenting_via_nested_attributes?
 
-            # push existing document to association
-            doc = association.klass.unscoped.find(converted)
-            update_document(doc, attrs)
-            existing.push(doc) unless destroyable?(attrs)
+              # push existing document to association
+              doc = association.klass.unscoped.find(converted)
+              update_document(doc, attrs)
+              existing.push(doc)
+            end
           else
             raise Errors::DocumentNotFound.new(association.klass, { _id: id, association.foreign_key => parent.id })
           end

spec/mongoid/attributes/nested_spec.rb

@@ -189,6 +189,29 @@
             expect(person2.posts.map(&:title)).to eq([ 'Reparented!' ])
           end
         end
+
+        context 'when _destroy is true for a document not in the relation' do
+          config_override :allow_reparenting_via_nested_attributes, true
+
+          before do
+            Person.send(:undef_method, :posts_attributes=)
+            Person.accepts_nested_attributes_for :posts, allow_destroy: true
+          end
+
+          let(:person3) do
+            Person.create!(
+              posts_attributes: { '0' => { id: post.id, _destroy: '1' } }
+            )
+          end
+
+          it 'does not raise UnknownAttribute' do
+            expect { person3 }.not_to raise_error
+          end
+
+          it 'does not add the document to the relation' do
+            expect(person3.posts).to be_empty
+          end
+        end
       end
     end
 
@@ -225,6 +248,27 @@
           )
           expect(person.preferences.map(&:name)).to eq([ preference_name ])
         end
+
+        context 'when _destroy is true for a document not in the relation' do
+          before do
+            Person.send(:undef_method, :preferences_attributes=)
+            Person.accepts_nested_attributes_for :preferences, allow_destroy: true
+          end
+
+          let(:person) do
+            Person.new(
+              preferences_attributes: { 0 => { id: preference.id, _destroy: '1' } }
+            )
+          end
+
+          it 'does not raise UnknownAttribute' do
+            expect { person }.not_to raise_error
+          end
+
+          it 'does not add the document to the relation' do
+            expect(person.preferences).to be_empty
+          end
+        end
       end
     end