diff --git a/functions/func.parserequest.php b/functions/func.parserequest.php
index 197396f..afa9c29 100644
--- a/functions/func.parserequest.php
+++ b/functions/func.parserequest.php
@@ -294,8 +294,10 @@ function request_get_condition_sql_string($id)
 		$document_fields = get_document_fields($document_id);
 
 		// ToDo
-		if (! is_array($document_fields[$field_id]))
-			$field_id = intval($document_fields[$field_id]);
+        if (isset($document_fields[$field_id]) && !is_array($document_fields[$field_id]))
+        {
+            $field_id = intval($document_fields[$field_id]);
+        }
 
 		if (empty($document_fields[$field_id]))
 			return '';
diff --git a/inc/query_variants/original_files/functions/func.parserequest.php b/inc/query_variants/original_files/functions/func.parserequest.php
index aa22e93..f837f01 100644
--- a/inc/query_variants/original_files/functions/func.parserequest.php
+++ b/inc/query_variants/original_files/functions/func.parserequest.php
@@ -271,8 +271,10 @@
 		$document_fields = get_document_fields($document_id);
 
 		// ToDo
-		if (! is_array($document_fields[$field_id]))
-			$field_id = intval($document_fields[$field_id]);
+        if (isset($document_fields[$field_id]) && !is_array($document_fields[$field_id]))
+        {
+            $field_id = intval($document_fields[$field_id]);
+        }
 
 		if (empty($document_fields[$field_id]))
 			return '';
diff --git a/inc/query_variants/safe_files/functions/func.parserequest.php b/inc/query_variants/safe_files/functions/func.parserequest.php
index 197396f..afa9c29 100644
--- a/inc/query_variants/safe_files/functions/func.parserequest.php
+++ b/inc/query_variants/safe_files/functions/func.parserequest.php
@@ -294,8 +294,10 @@ function request_get_condition_sql_string($id)
 		$document_fields = get_document_fields($document_id);
 
 		// ToDo
-		if (! is_array($document_fields[$field_id]))
-			$field_id = intval($document_fields[$field_id]);
+        if (isset($document_fields[$field_id]) && !is_array($document_fields[$field_id]))
+        {
+            $field_id = intval($document_fields[$field_id]);
+        }
 
 		if (empty($document_fields[$field_id]))
 			return '';