MAGETWO-84994: 8862: Can't emptying values by magento 2 api #916

 - Merge Pull Request magento-engcom/magento2ce#916 from RomaKis/magento2:8862
 - Merged commits:
   1. 1ef70f0

Author: Oleksii Korshenko

lib/internal/Magento/Framework/Webapi/ServiceInputProcessor.php

@@ -315,6 +315,10 @@ protected function _createDataObjectForTypeAndArrayValue($type, $customAttribute
      */
     public function convertValue($data, $type)
     {
+        if ($data === '') {
+            return $data;
+        }
+
         $isArrayType = $this->typeProcessor->isArrayType($type);
         if ($isArrayType && isset($data['item'])) {
             $data = $this->_removeSoapItemNode($data);
@@ -325,13 +329,7 @@ public function convertValue($data, $type)
             /** Complex type or array of complex types */
             if ($isArrayType) {
                 // Initializing the result for array type else it will return null for empty array
-                $result = is_array($data) ? [] : null;
-                $itemType = $this->typeProcessor->getArrayItemType($type);
-                if (is_array($data)) {
-                    foreach ($data as $key => $item) {
-                        $result[$key] = $this->_createFromArray($itemType, $item);
-                    }
-                }
+                $result = $this->getResultForArrayType($data, $type);
             } else {
                 $result = $this->_createFromArray($type, $data);
             }
@@ -385,4 +383,23 @@ protected function processInputError($inputError)
             }
         }
     }
+
+    /**
+     * @param mixed $data
+     * @param string $type
+     *
+     * @return array|null
+     */
+    private function getResultForArrayType($data, $type)
+    {
+        $result = is_array($data) ? [] : null;
+        $itemType = $this->typeProcessor->getArrayItemType($type);
+        if (is_array($data)) {
+            foreach ($data as $key => $item) {
+                $result[$key] = $this->_createFromArray($itemType, $item);
+            }
+        }
+
+        return $result;
+    }
 }

lib/internal/Magento/Framework/Webapi/Test/Unit/ServiceInputProcessorTest.php

@@ -569,4 +569,42 @@ public function invalidCustomAttributesDataProvider()
             ]
         ];
     }
+
+    /**
+     * Test if $data == '', then we have to get the same ''.
+     *
+     * @param string $data
+     * @param string $type
+     *
+     * @dataProvider convertValueWithEmptyValueDataProvider
+     */
+    public function testConvertValueWithEmptyValue($data, $type)
+    {
+        $actualData = $this->serviceInputProcessor->convertValue($data, $type);
+
+        $this->assertEquals($data, $actualData);
+    }
+
+    /**
+     * DataProvider for testConvertValueWithEmptyValue.
+     *
+     * @return array
+     */
+    public function convertValueWithEmptyValueDataProvider()
+    {
+        return [
+            [
+                '',
+                'string'
+            ],
+            [
+                '',
+                'int'
+            ],
+            [
+                '',
+                'float'
+            ],
+        ];
+    }
 }