I have content type ‘Document’ and added the ‘Upload document’ field with type ‘File’ I want to replace file and update the node. I’m using below code
function custom_file_upload_form_alter(&$form, $form_state, $form_id) {   if($form_id == "test_node_form") {     $form['#submit'][] = 'custom_fileupload_submit';   } }  function custom_fileupload_submit(&$form, &$form_state) {  $file = file_save_upload('field_document', array(     'file_validate_extensions' => array('pdf'), // Validate extensions.     'public://', FILE_EXISTS_REPLACE   ));   if ($file) {     // Move the file, into the Drupal file system     if ($file = file_move($file, 'public://', FILE_EXISTS_REPLACE)) {       // Save the file for use in the submit handler.       $form_state['storage']['file'] = $file;     }     else {       form_set_error('file', t('Failed to write the uploaded file the site's file folder.'));     }   }   else {     form_set_error('file', t('No file was uploaded.'));   } } 
Here file_save_upload() not working. I have debug the $file variable but it’s print nothing.