NEW Add new method TabSet::changeTabOrder().

src/Forms/TabSet.php

@@ -249,6 +249,39 @@ public function insertAfter($insertAfter, $field, $appendIfMissing = true)
         return parent::insertAfter($insertAfter, $field, $appendIfMissing);
     }
 
+    /**
+     * Change the order of tabs which are direct children of this TabSet by specifying an ordered list of
+     * tab names.
+     *
+     * This works well in conjunction with SilverStripe's scaffolding functions: take the scaffold, and
+     * shuffle the tabs around to the order that you want.
+     *
+     * Tab names should exclude prefixes. For example if this TabSet is "Root", include "Main" not "Root.Main"
+     */
+    public function changeTabOrder(array $tabNames): static
+    {
+        // Build a map of tabs indexed by their name. This will make the 2nd step much easier.
+        $existingTabs = [];
+        foreach ($this->children as $tab) {
+            $existingTabs[$tab->getName()] = $tab;
+        }
+
+        // Iterate through the ordered list of names, building a new array.
+        // While we're doing this, empty out $existingTabs so that we can keep track of leftovers.
+        // Unrecognised field names are okay; just ignore them.
+        $orderedTabs = [];
+        foreach ($tabNames as $tabName) {
+            if (isset($existingTabs[$tabName])) {
+                $orderedTabs[] = $existingTabs[$tabName];
+                unset($existingTabs[$tabName]);
+            }
+        }
+
+        // Add the leftover fields to the end of the ordered list.
+        $this->setTabs(FieldList::create([...$orderedTabs, ...$existingTabs]));
+        return $this;
+    }
+
     /**
      * Sets an additional default for $schemaData.
      * The existing keys are immutable. HideNav is added in this overriding method to ensure it is not ignored by

tests/php/Forms/TabSetTest.php

@@ -0,0 +1,37 @@
+<?php
+
+namespace SilverStripe\Forms\Tests;
+
+use SilverStripe\Dev\SapphireTest;
+use SilverStripe\Forms\FieldList;
+use SilverStripe\Forms\TabSet;
+
+class TabSetTest extends SapphireTest
+{
+    protected $usesDatabase = false;
+
+    public function testChangeTabOrder(): void
+    {
+        $tabSet = new TabSet('Root');
+        $fieldList = new FieldList([$tabSet]);
+        $fieldList->findOrMakeTab('Root.Main');
+        $fieldList->findOrMakeTab('Root.Next');
+        $fieldList->findOrMakeTab('Root.More');
+        $fieldList->findOrMakeTab('Root.Extra');
+        $fieldList->addFieldToTab('Root', new TabSet('SubTabSet'));
+        $fieldList->findOrMakeTab('Root.SubTabSet.Another');
+
+        // Reorder tabs - intentionally leaving some alone, which will be added to the end.
+        $tabSet->changeTabOrder([
+            'SubTabSet',
+            'More',
+            'Main',
+            'Non-Existent', // will be ignored
+            'Another', // will be ignored
+        ]);
+        // Order is correct
+        $this->assertSame(['SubTabSet', 'More', 'Main', 'Next', 'Extra'], $tabSet->getChildren()->column('Name'));
+        // Sub-tab is still there
+        $this->assertNotNull($fieldList->findTab('Root.SubTabSet.Another'));
+    }
+}