added regex for issn also some code cleanup

includes/form.inc

@@ -344,7 +344,7 @@ function upei_roblib_ill_request_form($form, &$form_state) {
     '#rows' => 2,
     '#title' => t('Source Title'),
     '#default_value' => upei_roblib_ill_get_request_variable('title'),
-    '#description' => 'Journal or Book Title',
+    '#description' => 'Journal or Book Title (Required)',
     '#size' => 50,
     '#required' => FALSE,
   );

includes/utilities.inc

@@ -55,6 +55,10 @@ function upei_roblib_ill_get_request_variable($variable) {
     $last_name = isset($_REQUEST['aulast']) ? $_REQUEST['aulast'] : NULL;
     return !empty($last_name) ? $last_name . ',' . $initial : '';
   }
+  if ($variable == 'issn' && !empty($_REQUEST[$variable])) {
+    // ebsco sometimes sends garbage as issns verify this is a valid issn before displaying the value in the form.
+    return preg_match('/^\d{4}-?\d{3}[\dxX]$/', $_REQUEST[$variable]) ? $_REQUEST[$variable] : '';
+  }
   return isset($_REQUEST[$variable]) ? $_REQUEST[$variable] : '';
 }