Unique key for DataObject

_config/unique-id.yml

@@ -0,0 +1,6 @@
+---
+Name: unique-id
+---
+SilverStripe\Core\Injector\Injector:
+  SilverStripe\ORM\UniqueKey\UniqueKeyInterface:
+    class: SilverStripe\ORM\UniqueKey\UniqueKeyService

docs/en/02_Developer_Guides/01_Templates/10_Unique_Keys.md

@@ -0,0 +1,48 @@
+---
+title: Generating Unique Keys
+summary: Outputting unique keys in templates.
+icon: code
+---
+
+# Unique Keys
+
+There are several cases where you may want to generate a unique key. For example:
+
+* populate `ID` attribute in your HTML output
+* key for partial cache
+
+This can be done simply by including following code in your template:
+
+```ss
+$DataObject.UniqueKey
+```
+
+`getUniqueKey` method is available on `DataObject` so you can use it on many object types like pages and blocks.
+
+## Customisation
+
+The unique key generation can be altered in two ways:
+
+* you can provide extra data to be used when generating a key via an extension
+* you can inject over the key generation service and write your own custom code
+
+### Extension point
+
+`cacheKeyComponent` extension point is located in `DataObject::getUniqueKeyComponents`.
+Use standard extension flow to define the  `cacheKeyComponent` method on your extension which is expected to return a `string`.
+This value will be used when unique key is generated. Common cases are:
+
+* versions - object in different version stages needs to have different unique keys
+* locales - object in different locales needs to have different unique keys
+
+### Custom service
+
+`UniqueKeyService` is used by default but you can use injector to override it with your custom service. For example:
+
+```yaml
+SilverStripe\Core\Injector\Injector:
+  SilverStripe\ORM\UniqueKey\UniqueKeyService:
+    class: App\Service\MyCustomService
+```
+
+Your custom service has to implement `UniqueKeyInterface`.

src/ORM/DataObject.php

@@ -18,15 +18,15 @@
 use SilverStripe\i18n\i18n;
 use SilverStripe\i18n\i18nEntityProvider;
 use SilverStripe\ORM\Connect\MySQLSchemaManager;
-use SilverStripe\ORM\FieldType\DBClassName;
-use SilverStripe\ORM\FieldType\DBEnum;
 use SilverStripe\ORM\FieldType\DBComposite;
 use SilverStripe\ORM\FieldType\DBDatetime;
+use SilverStripe\ORM\FieldType\DBEnum;
 use SilverStripe\ORM\FieldType\DBField;
 use SilverStripe\ORM\Filters\SearchFilter;
 use SilverStripe\ORM\Queries\SQLDelete;
-use SilverStripe\ORM\Queries\SQLInsert;
 use SilverStripe\ORM\Search\SearchContext;
+use SilverStripe\ORM\UniqueKey\UniqueKeyInterface;
+use SilverStripe\ORM\UniqueKey\UniqueKeyService;
 use SilverStripe\Security\Member;
 use SilverStripe\Security\Permission;
 use SilverStripe\Security\Security;
@@ -3234,9 +3234,10 @@ public static function get(
      */
     public static function get_one($callerClass, $filter = "", $cache = true, $orderby = "")
     {
-        $SNG = singleton($callerClass);
+        /** @var DataObject $singleton */
+        $singleton = singleton($callerClass);
 
-        $cacheComponents = [$filter, $orderby, $SNG->extend('cacheKeyComponent')];
+        $cacheComponents = [$filter, $orderby, $singleton->getUniqueKeyComponents()];
         $cacheKey = md5(serialize($cacheComponents));
 
         $item = null;
@@ -4186,6 +4187,28 @@ public function mergeRelatedObjects($list, $items)
         return $added;
     }
 
+    /**
+     * Generate a unique key for data object
+     * the unique key uses the @see DataObject::getUniqueKeyComponents() extension point so unique key modifiers
+     * such as versioned or fluent are covered
+     * i.e. same data object in different stages or different locales will produce different unique key
+     *
+     * recommended use:
+     * - when you need unique key for caching purposes
+     * - when you need unique id on the front end (for example JavaScript needs to target specific element)
+     *
+     * @return string
+     * @throws Exception
+     */
+    public function getUniqueKey(): string
+    {
+        /** @var UniqueKeyInterface $service */
+        $service = Injector::inst()->get(UniqueKeyInterface::class);
+        $keyComponents = $this->getUniqueKeyComponents();
+
+        return $service->generateKey($this, $keyComponents);
+    }
+
     /**
      * Merge single object into a list, but ensures that existing objects are not
      * re-added.
@@ -4211,4 +4234,21 @@ protected function mergeRelatedObject($list, $added, $item)
             $this->mergeRelatedObject($list, $added, $joined);
         }
     }
+
+    /**
+     * Extension point to add more cache key components.
+     * The framework extend method will return combined values from DataExtension method(s) as an array
+     * The method on your DataExtension class should return a single scalar value. For example:
+     *
+     * public function cacheKeyComponent()
+     * {
+     *      return (string) $this->owner->MyColumn;
+     * }
+     *
+     * @return array
+     */
+    private function getUniqueKeyComponents(): array
+    {
+        return $this->extend('cacheKeyComponent');
+    }
 }

src/ORM/UniqueKey/UniqueKeyInterface.php

@@ -0,0 +1,23 @@
+<?php
+
+namespace SilverStripe\ORM\UniqueKey;
+
+use SilverStripe\ORM\DataObject;
+
+/**
+ * Interface UniqueKeyInterface
+ *
+ * Useful when you want to implement your own custom service and use it instead of the default one (@see UniqueKeyService)
+ * your custom service needs to implement this interface
+ */
+interface UniqueKeyInterface
+{
+    /**
+     * Generate a unique key for data object
+     *
+     * @param DataObject $object
+     * @param array $keyComponents
+     * @return string
+     */
+    public function generateKey(DataObject $object, array $keyComponents = []): string;
+}

src/ORM/UniqueKey/UniqueKeyService.php

@@ -0,0 +1,40 @@
+<?php
+
+namespace SilverStripe\ORM\UniqueKey;
+
+use Exception;
+use SilverStripe\Core\ClassInfo;
+use SilverStripe\Core\Injector\Injectable;
+use SilverStripe\ORM\DataObject;
+
+/**
+ * Class UniqueKeyService
+ *
+ * Generate a unique key for data object
+ *
+ * recommended use:
+ * - when you need unique key for caching purposes
+ * - when you need unique id on the front end (for example JavaScript needs to target specific element)
+ */
+class UniqueKeyService implements UniqueKeyInterface
+{
+    use Injectable;
+
+    /**
+     * @param DataObject $object
+     * @param array $keyComponents key components are expected to be strings (or at least scalar values)
+     * @return string
+     * @throws Exception
+     */
+    public function generateKey(DataObject $object, array $keyComponents = []): string
+    {
+        $id = $object->isInDB() ? (string) $object->ID : bin2hex(random_bytes(16));
+        $class = ClassInfo::shortName($object);
+        $keyComponents = json_encode($keyComponents);
+        $hash = md5($keyComponents . $object->ClassName . $id);
+
+        // note: class name and id are added just for readability as the hash already contains all parts
+        // needed to create a unique key
+        return sprintf('%s-%s-%s', $class, $id, $hash);
+    }
+}

tests/php/ORM/UniqueKey/ExtraKeysExtension.php

@@ -0,0 +1,14 @@
+<?php
+
+namespace SilverStripe\Tests\ORM\UniqueKey;
+
+use SilverStripe\Core\Extension;
+use SilverStripe\Dev\TestOnly;
+
+class ExtraKeysExtension extends Extension implements TestOnly
+{
+    public function cacheKeyComponent(): string
+    {
+        return 'extra-key';
+    }
+}

tests/php/ORM/UniqueKey/Mountain.php

@@ -0,0 +1,21 @@
+<?php
+
+namespace SilverStripe\Tests\ORM\UniqueKey;
+
+use SilverStripe\Dev\TestOnly;
+use SilverStripe\ORM\DataObject;
+
+class Mountain extends DataObject implements TestOnly
+{
+    /**
+     * @var string
+     */
+    private static $table_name = 'UniqueKeyTest_Mountain';
+
+    /**
+     * @var array
+     */
+    private static $db = [
+        'Title' => 'Varchar',
+    ];
+}

tests/php/ORM/UniqueKey/River.php

@@ -0,0 +1,21 @@
+<?php
+
+namespace SilverStripe\Tests\ORM\UniqueKey;
+
+use SilverStripe\Dev\TestOnly;
+use SilverStripe\ORM\DataObject;
+
+class River extends DataObject implements TestOnly
+{
+    /**
+     * @var string
+     */
+    private static $table_name = 'UniqueKeyTest_River';
+
+    /**
+     * @var array
+     */
+    private static $db = [
+        'Title' => 'Varchar',
+    ];
+}

tests/php/ORM/UniqueKey/ServiceTest.php

@@ -0,0 +1,56 @@
+<?php
+
+namespace SilverStripe\Tests\ORM\UniqueKey;
+
+use SilverStripe\Core\Injector\Injector;
+use SilverStripe\Dev\SapphireTest;
+use SilverStripe\ORM\DataObject;
+
+class ServiceTest extends SapphireTest
+{
+    /**
+     * @var array
+     */
+    protected static $extra_dataobjects = [
+        River::class,
+        Mountain::class,
+    ];
+
+    /**
+     * @param int $id
+     * @param string $class
+     * @param bool $extraKeys
+     * @param string $expected
+     * @dataProvider uniqueKeysProvider
+     */
+    public function testUniqueKey(int $id, string $class, bool $extraKeys, string $expected): void
+    {
+        if ($extraKeys) {
+            $class::add_extension(ExtraKeysExtension::class);
+        }
+
+        /** @var DataObject $object */
+        $object = Injector::inst()->create($class);
+        $object->ID = $id;
+
+        $this->assertEquals($expected, $object->getUniqueKey());
+
+        if ($extraKeys) {
+            $class::remove_extension(ExtraKeysExtension::class);
+        }
+    }
+
+    public function uniqueKeysProvider(): array
+    {
+        return [
+            [1, River::class, false, 'River-1-8d3310e232f75a01f5a0c9344655263d'],
+            [1, River::class, true, 'River-1-ff2ea6e873a9e28538dd4af278f35e08'],
+            [2, River::class, false, 'River-2-c562c31e5c2caaabb124b46e274097c1'],
+            [2, River::class, true, 'River-2-410c1eb12697a26742bbe4b059625ab2'],
+            [1, Mountain::class, false, 'Mountain-1-93164c0f65fa28778fb75163c1e3e2f0'],
+            [1, Mountain::class, true, 'Mountain-1-2daf208e0b89252e5d239fbc0464a517'],
+            [2, Mountain::class, false, 'Mountain-2-62366f2b970a64de6f2a8e8654f179d5'],
+            [2, Mountain::class, true, 'Mountain-2-a724046b14d331a1486841eaa591d109'],
+        ];
+    }
+}