fix: belongs_to field should use association primary_key

lib/avo/fields/belongs_to_field.rb

@@ -115,6 +115,13 @@ def options
         values_for_type
       end
 
+      def primary_key
+        @primary_key ||= reflection.association_primary_key
+        # Quick fix for "Polymorphic associations do not support computing the class."
+      rescue
+        nil
+      end
+
       def values_for_type(model = nil)
         resource = target_resource
         resource = Avo.resource_manager.get_resource_by_model_class model if model.present?
@@ -126,6 +133,7 @@ def values_for_type(model = nil)
         end
 
         query.all.limit(Avo.configuration.associations_lookup_list_limit).map do |record|
+          # to_param uses slug so checking primary_key is unnecessary
           [resource.new(record: record).record_title, record.to_param]
         end.tap do |options|
           options << t("avo.more_records_available") if options.size == Avo.configuration.associations_lookup_list_limit
@@ -212,14 +220,16 @@ def fill_field(record, key, value, params)
           if valid_model_class.blank? || id_from_param.blank?
             record.send(:"#{polymorphic_as}_id=", nil)
           else
-            record_id = target_resource(record:, polymorphic_model_class: value.safe_constantize).find_record(id_from_param).id
+            found_record = target_resource(record:, polymorphic_model_class: value.safe_constantize).find_record(id_from_param)
+
+            record_id = found_record&.send(primary_key.presence || :id)
 
             record.send(:"#{polymorphic_as}_id=", record_id)
           end
         else
-          record_id = value.blank? ? value : target_resource(record:).find_record(value).id
+          found_record = value.present? ? target_resource(record:).find_record(value) : nil
 
-          record.send(:"#{key}=", record_id)
+          record.send(:"#{key}=", found_record&.send(primary_key.presence || :id))
         end
 
         record

spec/features/avo/belongs_to_polymorphic_spec.rb

@@ -76,6 +76,17 @@
           expect(page.body).to have_text "Commentable"
           expect(field_element_by_resource_id("commentable", comment.id)).to have_link project.name, href: "/admin/resources/projects/#{project.id}"
         end
+
+        context "custom primary key (UUID) handling" do
+          let!(:uuid_project) { create :project, id: SecureRandom.uuid, name: "UUID Project" }
+          let!(:comment) { create :comment, commentable: uuid_project }
+
+          it "assigns the correct uuid to the polymorphic association" do
+            expect(comment.commentable_id).to eq(uuid_project.id)
+          end
+
+          # ToDo spec with relation belongs_to with primary_key
+        end
       end
     end
   end

spec/features/avo/belongs_to_spec.rb

@@ -83,6 +83,21 @@
       end
     end
 
+    context "custom primary key (UUID) handling" do
+      let!(:uuid_user) { create :user, id: SecureRandom.uuid }
+      let!(:post) { create :post, user: uuid_user }
+
+      it "displays the user link using the UUID and stores the correct foreign key" do
+        visit "/admin/resources/posts/#{post.slug}"
+
+        expect(page).to have_link uuid_user.name, href: "/admin/resources/users/#{uuid_user.slug}?via_record_id=#{post.slug}&via_resource_class=Avo%3A%3AResources%3A%3APost"
+
+        post.reload
+
+        expect(post.user_id).to eq(uuid_user.id)
+      end
+    end
+
     describe "with user attached" do
       let!(:post) { create :post, user: admin }
       let!(:second_user) { create :user }