From eb18c4ae88cce5c8c5d75d0b4eaa5fd063979a6f Mon Sep 17 00:00:00 2001
From: Andrew Konchin <andry.konchin@gmail.com>
Date: Sun, 20 Aug 2023 23:24:31 +0300
Subject: [PATCH] Fix saving persisted model and delete item attributes with
 nil values if config.store_attribute_with_nil_value = false

---
 .../adapter_plugin/aws_sdk_v3/item_updater.rb | 19 ++++++++++-
 spec/dynamoid/persistence_spec.rb             | 32 +++++++++++++++++--
 2 files changed, 47 insertions(+), 4 deletions(-)

diff --git a/lib/dynamoid/adapter_plugin/aws_sdk_v3/item_updater.rb b/lib/dynamoid/adapter_plugin/aws_sdk_v3/item_updater.rb
index f711b086..cac53c6f 100644
--- a/lib/dynamoid/adapter_plugin/aws_sdk_v3/item_updater.rb
+++ b/lib/dynamoid/adapter_plugin/aws_sdk_v3/item_updater.rb
@@ -50,7 +50,20 @@ def delete(values)
         # Replaces the values of one or more attributes
         #
         def set(values)
-          @updates.merge!(sanitize_attributes(values))
+          values_sanitized = sanitize_attributes(values)
+
+          if Dynamoid.config.store_attribute_with_nil_value
+            @updates.merge!(values_sanitized)
+          else
+            # delete explicitly attributes if assigned nil value and configured
+            # to not store nil values
+            values_to_update = values_sanitized.select { |_, v| !v.nil? }
+            values_to_delete = values_sanitized.select { |_, v| v.nil? }
+
+            @updates.merge!(values_to_update)
+            @deletions.merge!(values_to_delete)
+          end
+
         end
 
         #
@@ -85,6 +98,10 @@ def attribute_updates
 
         private
 
+        # Keep in sync with AwsSdkV3.sanitize_item.
+        #
+        # The only difference is that to update item we need to track whether
+        # attribute value is nil or not.
         def sanitize_attributes(attributes)
           attributes.transform_values do |v|
             if v.is_a?(Hash)
diff --git a/spec/dynamoid/persistence_spec.rb b/spec/dynamoid/persistence_spec.rb
index 7ddeb5fc..26d57b25 100644
--- a/spec/dynamoid/persistence_spec.rb
+++ b/spec/dynamoid/persistence_spec.rb
@@ -2902,32 +2902,58 @@ def around_save_callback
       end
 
       context 'true', config: { store_attribute_with_nil_value: true } do
-        it 'keeps document attribute with nil' do
+        it 'keeps document attribute with nil when model is not persisted' do
           obj = klass.new(age: nil)
           obj.save
 
           expect(raw_attributes(obj)).to include(age: nil)
         end
+
+        it 'keeps document attribute with nil when model is persisted' do
+          obj = klass.create(age: 42)
+          obj.age = nil
+          obj.save
+
+          expect(raw_attributes(obj)).to include(age: nil)
+        end
       end
 
       context 'false', config: { store_attribute_with_nil_value: false } do
-        it 'does not keep document attribute with nil' do
+        it 'does not keep document attribute with nil when model is not persisted' do
           obj = klass.new(age: nil)
           obj.save
 
           # doesn't contain :age key
           expect(raw_attributes(obj).keys).to contain_exactly(:id, :created_at, :updated_at)
         end
+
+        it 'does not keep document attribute with nil when model is persisted' do
+          obj = klass.create!(age: 42)
+          obj.age = nil
+          obj.save
+
+          # doesn't contain :age key
+          expect(raw_attributes(obj).keys).to contain_exactly(:id, :created_at, :updated_at)
+        end
       end
 
       context 'by default', config: { store_attribute_with_nil_value: nil } do
-        it 'does not keep document attribute with nil' do
+        it 'does not keep document attribute with nil when model is not persisted' do
           obj = klass.new(age: nil)
           obj.save
 
           # doesn't contain :age key
           expect(raw_attributes(obj).keys).to contain_exactly(:id, :created_at, :updated_at)
         end
+
+        it 'does not keep document attribute with nil when model is persisted' do
+          obj = klass.create!(age: 42)
+          obj.age = nil
+          obj.save
+
+          # doesn't contain :age key
+          expect(raw_attributes(obj).keys).to contain_exactly(:id, :created_at, :updated_at)
+        end
       end
     end