Add :filename Modifier to Single File Upload Field

// adds :filename modifier to the single file upload field
add_filter( 'gform_merge_tag_filter', function ( $value, $merge_tag, $modifier, $field, $raw_value, $format ) {

   if ( $merge_tag != 'all_fields' && $field->type == 'fileupload' && $modifier == 'filename' ) {

      $value    = str_replace( ' ', '%20', $raw_value );
      $pathinfo = pathinfo( $value );
      $value    = rgar( $pathinfo, 'basename' );

   }

   return $value;

}, 10, 6 );

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