unique rules, allow product id to be null in product photos

src/Model/Entity/ProductPhoto.php

@@ -10,7 +10,7 @@ use Cake\ORM\Entity;
  * ProductPhoto Entity
  *
  * @property string $id
- * @property string $product_id
+ * @property string|null $product_id
  * @property string|null $product_category_id
  * @property string|null $product_sku_id
  * @property string $photo_dir
@@ -55,6 +55,8 @@ class ProductPhoto extends Entity
         'deleted' => true,
 
         // entities
-        'product' => true,
+        'product' => false,
+        'product_sku' => false,
+        'product_category' => false,
     ];
 }

src/Model/Table/ProductCategoryAttributeOptionsTable.php

@@ -108,6 +108,7 @@ class ProductCategoryAttributeOptionsTable extends Table
     public function buildRules(RulesChecker $rules): RulesChecker
     {
         $rules->add($rules->existsIn(['product_category_attribute_id'], 'ProductCategoryAttributes'), ['errorField' => 'product_category_attribute_id']);
+        $rules->add($rules->isUnique(['attribute_value', 'product_category_attribute_id']));
 
         return $rules;
     }

src/Model/Table/ProductCategoryVariantOptionsTable.php

@@ -105,6 +105,7 @@ class ProductCategoryVariantOptionsTable extends Table
     public function buildRules(RulesChecker $rules): RulesChecker
     {
         $rules->add($rules->existsIn(['product_category_variant_id'], 'ProductCategoryVariants'), ['errorField' => 'product_category_variant_id']);
+        $rules->add($rules->isUnique(['variant_value', 'product_category_variant_id']));
 
         return $rules;
     }