magento/magento2#87588: Fix json encoded attribute backend type to not encode attribute value multiple times magento#13551

Author: p-bystritsky

app/code/Magento/Eav/Model/Entity/Attribute/Backend/JsonEncoded.php

@@ -41,7 +41,7 @@ public function beforeSave($object)
     {
         // parent::beforeSave() is not called intentionally
         $attrCode = $this->getAttribute()->getAttributeCode();
-        if ($object->hasData($attrCode) && !is_string($object->getData($attrCode))) {
+        if ($object->hasData($attrCode) && !$this->isJsonEncoded((string)$object->getData($attrCode))) {
             $object->setData($attrCode, $this->jsonSerializer->serialize($object->getData($attrCode)));
         }
         return $this;
@@ -61,4 +61,22 @@ public function afterLoad($object)
         $object->setData($attrCode, $this->jsonSerializer->unserialize($object->getData($attrCode) ?: '{}'));
         return $this;
     }
+
+    /**
+     * Returns true if given param is a valid json value else false.
+     *
+     * @param string $value
+     * @return bool
+     */
+    private function isJsonEncoded(string $value): bool
+    {
+        $result = true;
+        try {
+            $this->jsonSerializer->unserialize($value);
+        } catch (\InvalidArgumentException $e) {
+            $result =  false;
+        }
+
+        return $result;
+    }
 }