Only load linkfield when object exists and move CMSFields to beforeUp…

…date hook

changelog.md

@@ -8,4 +8,9 @@ This file logs major changes for the SilverStripe System Mesages module.
 
 ## 1.0.1
 
-* Minor updates to readme and travis config
+* Minor updates to readme and travis config
+
+## 2.0.0
+
+* Upgrade to Silverstripe 4
+* Add ability to add a delay (in seconds) to the modal

src/model/SystemMessage.php

@@ -35,13 +35,17 @@ class SystemMessage extends DataObject
     );
 
     private static $has_one = array(
-        'Link'		=> Link::class
+        'Link'      => Link::class
     );
 
     private static $belongs_many_many = array(
         "ClosedBy" => Member::class
     );
 
+    private static $field_labels = array(
+        'Link' => 'Link to page or file'
+    );
+
     private static $summary_fields = array(
         "Content.Summary" => "Content",
         "StartDate"       => "Starts",
@@ -150,15 +154,29 @@ public function UseBootstrap()
 
     public function getCMSFields()
     {
-        $fields = parent::getCMSFields();
-
-        $fields->removeByName('LinkID');
-
-		$fields->addFieldToTab(
-            'Root.Main', 
-            LinkField::create('Link', 'Link to page or file', $this)
+        $self = $this;
+
+        $this->beforeUpdateCMSFields(
+            function ($fields) use ($self) {
+                $fields->removeByName('LinkID');
+
+                // Add description to delay field
+                $delay_field = $fields->dataFieldByName('Delay');
+                if (!empty($delay_field)) {
+                    $delay_field->setDescription(
+                        _t(__CLASS__ . ".DelayDescription", 'Delay in seconds to open this message')
+                    );
+                }
+
+                if ($self->exists()) {
+                    $fields->addFieldToTab(
+                        'Root.Main',
+                        LinkField::create('Link', $self->fieldLabel('Link'), $this)
+                    );
+                }
+            }
         );
 
-        return $fields;
+        return parent::getCMSFields();
     }
-}
+}