Hook Ordering

When to Use

Your implementation must run before or after another module's, or you must stop another module's implementation from running. Since 11.2.0 you declare this in attributes; hook_module_implements_alter() is on its way out.

Decision

Default order, from core/core.api.php (@defgroup hooks): module weight, then alphabetical by module name. Within one module, procedural implementations run before OOP implementations of the same hook (11.2.0, change record 3515207).

If you need...	Use...	Why
Your implementation first or last among all modules	`order: Order::First` or `order: Order::Last` on your `#[Hook]`	`FirstOrLast` operation moves your identifier to the array start or end
Yours before or after named modules	`order: new OrderBefore(modules: ['a', 'b'])` / `new OrderAfter(modules: [...])`	`BeforeOrAfter` splices yours immediately before the earliest, or after the latest, of the named modules
Yours before or after one specific class method	`new OrderAfter(classesAndMethods: [[Foo::class, 'method']])`	Same operation, finer target. Use `[ProceduralCall::class, 'function_name']` to target a procedural implementation
Another module's implementation moved, without touching that module	`#[ReorderHook(hook, class, method, order)]` on any class or method in your `src/Hook/`	Runs after every `#[Hook(order:)]` is applied (`core.api.php`, "ordering_other_module_hooks"). 11.2.0, change record 3497308
Another module's implementation removed	`#[RemoveHook(hook, class, method)]`	11.2.0, change record 3496786
Support for core before 11.2.0	Keep `hook_module_implements_alter()` and mark it `#[LegacyModuleImplementsAlter]`	On 11.2+ the attribute stops the procedural function from running so the attribute ordering wins. Without the attribute the function still runs but is deprecated 11.2.0, removed 12.0.0 (change record 3496788)

Pattern

order: on the implementation:

use Drupal\Core\Hook\Attribute\Hook;
use Drupal\Core\Hook\Order\Order;
use Drupal\Core\Hook\Order\OrderAfter;

#[Hook('entity_presave', order: Order::Last)]
public function entityPresaveLast(EntityInterface $entity): void {}

#[Hook('form_alter', order: new OrderAfter(modules: ['field_group']))]
public function formAlter(array &$form, FormStateInterface $form_state, string $form_id): void {}

Reordering another module, the example from change record 3497308:

use Drupal\Core\Hook\Attribute\ReorderHook;
use Drupal\Core\Hook\Order\OrderBefore;
use Drupal\content_moderation\Hook\ContentModerationHooks;

#[ReorderHook('entity_presave', class: ContentModerationHooks::class, method: 'entityPresave', order: new OrderBefore(modules: ['workspaces']))]
#[Hook('entity_presave')]
public function entityPresave(EntityInterface $entity): void {}

Removing another module's implementation:

use Drupal\Core\Hook\Attribute\RemoveHook;

#[RemoveHook('form_alter', class: OtherModuleHooks::class, method: 'formAlter')]
final class MyHooks {}

The attributes take effect wherever they sit inside src/Hook/; core recommends placing #[ReorderHook] on the implementation that needs the other one moved (change record 3497308).

Common Mistakes

Looking for a priority: parameter → there is none. Ordering is order: on #[Hook], #[ReorderHook], #[RemoveHook].
new OrderBefore() with no arguments → LogicException('Order must provide either modules or class-method pairs to order against.') (core/lib/Drupal/Core/Hook/Order/RelativeOrderBase.php).
Targeting a class-form implementation with method: 'someName' → the target method is '__invoke' when the #[Hook] sits on the class.
Ordering against a module that does not implement the hook → silent no-op. BeforeOrAfter::apply() returns without change when the reference identifier is absent.
Assuming Order::First on two modules gives a defined order → both move to the front; the last applied wins. Use OrderBefore against the other module instead.
Using order:, #[ReorderHook], or #[RemoveHook] in a theme → LogicException at container build. See Theme Hooks (OOP).

Hook Ordering

When to Use

Decision

Pattern

Common Mistakes

See Also