diff --git a/api/v3/Documents.php b/api/v3/Documents.php
index 06caeec..92b8eb6 100644
--- a/api/v3/Documents.php
+++ b/api/v3/Documents.php
@@ -19,7 +19,6 @@ function _civicrm_api3_documents_import_spec(array &$params) : void {
     'type' => CRM_Utils_Type::T_INT,
     'title' => E::ts('Custom Field ID'),
     'api.required' => 'TRUE',
-    'options' => get_custom_fields_ids_files(),
   ];
 }
 
@@ -30,6 +29,22 @@ function _civicrm_api3_documents_import_spec(array &$params) : void {
  * @return array
  */
 function civicrm_api3_documents_import(array $params) : array {
+
+  $customFieldId = $params['custom_field_id'];
+  try{
+    $custom_field = civicrm_api3('CustomField', 'getSingle', [
+      'id' => $customFieldId,
+      'api.CustomGroup.getSingle' => [],
+    ]);
+  }
+  catch(Exception $e){
+    return civicrm_api3_create_error("custom_field_id does not exists", $params);
+  }
+
+  if($custom_field['data_type'] != "File"){
+    return civicrm_api3_create_error("custom_field_id is not type File", $params);
+  }
+
   $custom_field = civicrm_api3('CustomField', 'getSingle', [
     'id' => $params['custom_field_id'],
     'api.CustomGroup.getSingle' => [],
@@ -68,8 +83,6 @@ function civicrm_api3_documents_import(array $params) : array {
     $filePath = Civi::paths()->getPath("[civicrm.files]/custom/{$file_ori['uri']}");
     $new_path = CRM_Utils_File::duplicate($filePath);
 
-    $file_ori['mime_type'];
-
     $repository = CRM_Documents_Entity_DocumentRepository::singleton();
     $document = new CRM_Documents_Entity_Document();
     $document->setSubject($params['subject']);
@@ -102,30 +115,5 @@ function civicrm_api3_documents_import(array $params) : array {
     $count++;
   }
   // ToDo better return of API
-  $values_imported = ['count' => $count];
-  return civicrm_api3_create_success($values_imported, $params, 'Documents', 'import');
+  return civicrm_api3_create_success(['count' => $count], $params, 'Documents', 'import');
 }
-
-/**
- * Get the custom fields avalibles to use
- *
- * @return array
- */
-function get_custom_fields_ids_files () : array {
-  $custom_fields_files = civicrm_api3('CustomField', 'get', [
-    'sequential' => 1,
-    'return' => ["id"],
-    'data_type' => "File",
-    'options' => ['limit' => 0],
-  ]);
-
-  if (!is_array($custom_fields_files['values'])) {
-    throw new API_Exception(E::ts('Not exist custom fields of type File.'));
-  }
-
-  $custom_fields_avalible = [];
-  foreach ($custom_fields_files['values'] as $custom_fields_files) {
-    $custom_fields_avalible[$custom_fields_files['id']] = $custom_fields_files['id'];
-  }
-  return $custom_fields_avalible;
-}
\ No newline at end of file