New interface to upsert custom fields

app/models/concerns/has_custom_fields.rb

@@ -155,6 +155,20 @@ module HasCustomFields
     !@custom_fields || @custom_fields_orig == @custom_fields
   end
 
+  # `upsert_custom_fields` will only insert/update existing fields, and will not
+  # delete anything. It is safer under concurrency and is recommended when
+  # you just want to attach fields to things without maintaining a specific
+  # set of fields.
+  def upsert_custom_fields(fields)
+    fields.each do |k, v|
+      row_count = _custom_fields.where(name: k).update_all(value: v)
+      if row_count == 0
+        _custom_fields.create!(name: k, value: v)
+      end
+      custom_fields[k] = v
+    end
+  end
+
   def save_custom_fields(force = false)
     if force || !custom_fields_clean?
       dup = @custom_fields.dup

spec/components/concern/has_custom_fields_spec.rb

@@ -215,5 +215,31 @@ describe HasCustomFields do
       test_item.save_custom_fields(true)
       expect(test_item.reload.custom_fields).to eq(expected)
     end
+
+    describe "upsert_custom_fields" do
+      it 'upserts records' do
+        test_item = CustomFieldsTestItem.create
+        test_item.upsert_custom_fields('hello' => 'world', 'abc' => 'def')
+
+        # In memory
+        expect(test_item.custom_fields['hello']).to eq('world')
+        expect(test_item.custom_fields['abc']).to eq('def')
+
+        # Persisted
+        test_item.reload
+        expect(test_item.custom_fields['hello']).to eq('world')
+        expect(test_item.custom_fields['abc']).to eq('def')
+
+        # In memory
+        test_item.upsert_custom_fields('abc' => 'ghi')
+        expect(test_item.custom_fields['hello']).to eq('world')
+        expect(test_item.custom_fields['abc']).to eq('ghi')
+
+        # Persisted
+        test_item.reload
+        expect(test_item.custom_fields['hello']).to eq('world')
+        expect(test_item.custom_fields['abc']).to eq('ghi')
+      end
+    end
   end
 end