feat: Add afterCreateUsing callback to Repeater for relationship items

packages/forms/docs/12-repeater.md

@@ -439,6 +439,28 @@ Repeater::make('qualifications')
 
 <UtilityInjection set="formFields" version="4.x" extras="Data;;array<string, mixed>;;$data;;The data that is being saved by the repeater.">You can inject various utilities into the function passed to `mutateRelationshipDataBeforeSaveUsing()` as parameters.</UtilityInjection>
 
+### Running code after creating a related item
+
+You may run code after a new related item is created in the database using the `afterCreateUsing()` method. This method accepts a closure that receives the current item's data in a `$data` variable and the newly created record in a `$record` variable. This is useful when you need the record's ID to perform additional operations, such as attaching pivot data:
+
+```php
+use Filament\Forms\Components\Repeater;
+use Illuminate\Database\Eloquent\Model;
+
+Repeater::make('variants')
+    ->relationship()
+    ->schema([
+        // ...
+    ])
+    ->afterCreateUsing(function (array $data, Model $record): void {
+        if (isset($data['attributes'])) {
+            $record->attributes()->attach($data['attributes']);
+        }
+    })
+```
+
+<UtilityInjection set="formFields" version="5.x" extras="Data;;array<string, mixed>;;$data;;The data that was used to create the record.||Record;;Illuminate\Database\Eloquent\Model;;$record;;The newly created record.">You can inject various utilities into the function passed to `afterCreateUsing()` as parameters.</UtilityInjection>
+
 ### Modifying related records after retrieval
 
 You may filter or modify the related records of a repeater after they are retrieved from the database using the `modifyRecordsUsing` argument. This method accepts a function that receives a `Collection` of related records. You should return the modified collection.

packages/forms/src/Components/Repeater.php

@@ -102,6 +102,8 @@ class Repeater extends Field implements CanConcealComponents, HasExtraItemAction
 
     protected ?Closure $mutateRelationshipDataBeforeSaveUsing = null;
 
+    protected ?Closure $afterCreateUsing = null;
+
     /**
      * @var array<string, mixed> | null
      */
@@ -1003,6 +1005,7 @@ public function relationship(string | Closure | null $name = null, ?Closure $mod
                 }
 
                 $record = $relationship->save($record);
+                $component->afterCreate($itemData, $record);
                 $item->model($record)->saveRelationships();
                 $existingRecords->push($record);
             }
@@ -1353,6 +1356,30 @@ public function mutateRelationshipDataBeforeSave(array $data, Model $record): ?a
         return $data;
     }
 
+    public function afterCreateUsing(?Closure $callback): static
+    {
+        $this->afterCreateUsing = $callback;
+
+        return $this;
+    }
+
+    public function afterCreate(array $data, Model $record): void
+    {
+        if ($this->afterCreateUsing instanceof Closure) {
+            $this->evaluate(
+                $this->afterCreateUsing,
+                namedInjections: [
+                    'data' => $data,
+                    'record' => $record,
+                ],
+                typedInjections: [
+                    Model::class => $record,
+                    $record::class => $record,
+                ],
+            );
+        }
+    }
+
     public function canConcealComponents(): bool
     {
         return $this->isCollapsible();