Add validation for step form

classes/local/form/form_step_instance.php

@@ -191,4 +191,22 @@ public function definition_after_data() {
         }
     }
 
+    /** Validate the form.
+     * @param array $data array of ("fieldname"=>value) of submitted data
+     * @param array $files array of uploaded files "element_name"=>tmp_file_path
+     * @return array of "element_name"=>"error_description" if there are errors,
+     *         or an empty array if everything is OK (true allowed for backwards compatibility too).
+     * @throws \coding_exception
+     */
+    public function validation($data, $files) {
+        $error = parent::validation($data, $files);
+        if (empty($data['instancename'])) {
+            $error['instancename'] = get_string('required');
+        }
+
+        $this->lib->extend_add_instance_form_validation($error, $data);
+
+        return $error;
+    }
+
 }

step/lib.php

@@ -134,6 +134,14 @@ public function extend_add_instance_form_definition($mform) {
     public function extend_add_instance_form_definition_after_data($mform, $settings) {
     }
 
+    /**
+     * This method can be overriden, to add additional data validation to the instance form.
+     * @param array $error Array containing all errors.
+     * @param array $data Data passed from the moodle form to be validated
+     */
+    public function extend_add_instance_form_validation(&$error, $data) {
+    }
+
     /**
      * This method can be overridden. It is called when a course and the
      * corresponding process get deleted.