diff --git a/src/Generator/IndexDocumentGenerator.php b/src/Generator/IndexDocumentGenerator.php
index d09a59f..43ba9ec 100644
--- a/src/Generator/IndexDocumentGenerator.php
+++ b/src/Generator/IndexDocumentGenerator.php
@@ -94,11 +94,6 @@ protected function populateIndexDocument(
             $dataTransformerOptions = $documentDefinitionOptions['data_transformer'];
             $transformedData = $this->dispatchResourceFieldTransformer($dataTransformerOptions, $resourceScaffolderName, $resourceContainer);
 
-            if ($transformedData === null) {
-                // no error: transformer is allowed to refuse data
-                continue;
-            }
-
             $optionFieldContainer = new OptionFieldContainer($fieldName, $transformedData);
             $indexDocument->addOptionField($optionFieldContainer);
         }
@@ -133,11 +128,6 @@ protected function processDocumentDataTransformerField(
 
         $transformedData = $this->dispatchResourceFieldTransformer($dataTransformerOptions, $resourceScaffolderName, $resourceContainer);
 
-        if ($transformedData === null) {
-            // no error: transformer is allowed to refuse data
-            return;
-        }
-
         if ($fieldType === 'pre_process_definition') {
 
             $documentDefinition->setCurrentLevel($fieldDefinitionOptions['level']);
@@ -202,6 +192,10 @@ protected function dispatchResourceFieldTransformer(array $options, string $disp
                 sprintf('Error while transform field resource with service "%s": %s', $fieldTransformerName, $e->getMessage()));
         }
 
+        if ($transformedData === '') {
+            return null;
+        }
+
         return $transformedData;
     }
 
@@ -226,10 +220,6 @@ protected function dispatchIndexTransformer(ContextDefinitionInterface $contextD
             );
         }
 
-        if ($indexFieldData === null) {
-            return null;
-        }
-
         return $indexFieldData;
     }