feat: Add groupBy as a new feature in repository

docs-v2/content/en/api/repositories.md

@@ -819,3 +819,14 @@ public static $withs = ['posts'];
 `withs` is not a typo. Laravel uses the `with` property on models, on repositories we use `$withs`, it's not a typo.
 
 </alert>
+
+## Group by
+
+The group by filter is useful when you want to group the results by a certain column.
+
+```php
+class PostRepository extends Repository
+{
+    public static array $groupBy = ['user_id'];
+}
+```

src/Http/Requests/RestifyRequest.php

@@ -77,4 +77,9 @@ public function filters(): array
             ? $this->input('filters', [])
             : (json_decode(base64_decode($this->input('filters')), true) ?? []);
     }
+
+    public function groupBy(): ?string
+    {
+        return $this->input('group_by');
+    }
 }

src/Repositories/Repository.php

@@ -91,6 +91,11 @@ class Repository implements JsonSerializable, RestifySearchable
      */
     public static array $sort;
 
+    /**
+     * The list of fields that can be used for grouping.
+     */
+    public static array $groupBy = [];
+
     /**
      * Attribute that should be used for displaying single model.
      */

src/Services/Search/RepositorySearchService.php

@@ -43,6 +43,8 @@ public function search(RestifyRequest $request, Repository $repository): Builder
 
         $query = $this->applyFilters($request, $repository, $query);
 
+        $query = $this->applyGroupBy($request, $repository, $query);
+
         $ordersBuilder = $this->prepareOrders($request, $query);
 
         return tap(
@@ -217,6 +219,29 @@ protected function applyFilters(RestifyRequest $request, Repository $repository,
         return $query;
     }
 
+    protected function applyGroupBy(RestifyRequest $request, Repository $repository, $query)
+    {
+        if (! $request->has('group_by')) {
+            return $query;
+        }
+
+        $model = $query->getModel();
+        $groupByColumns = explode(',', $request->input('group_by'));
+
+        foreach ($groupByColumns as $column) {
+            if (! in_array($column, $repository::$groupBy)) {
+                abort(422, sprintf(
+                    'The column [%s] is not allowed for grouping. Allowed columns are: %s',
+                    $column,
+                    implode(', ', $repository::$groupBy)
+                ));
+            }
+            $query->groupBy($model->qualifyColumn($column));
+        }
+
+        return $query;
+    }
+
     public static function make(): static
     {
         return new static;

tests/Feature/RepositoryGroupByTest.php

@@ -0,0 +1,57 @@
+<?php
+
+namespace Binaryk\LaravelRestify\Tests\Feature;
+
+use Binaryk\LaravelRestify\Tests\Fixtures\User\User;
+use Binaryk\LaravelRestify\Tests\Fixtures\User\UserRepository;
+use Binaryk\LaravelRestify\Tests\IntegrationTestCase;
+
+class RepositoryGroupByTest extends IntegrationTestCase
+{
+    public function test_it_can_group_by_the_results(): void
+    {
+        User::factory(4)->create([
+            'name' => 'John Doe',
+        ]);
+
+        User::factory(4)->create([
+            'name' => 'Second John Doe',
+        ]);
+
+        UserRepository::$groupBy = ['name'];
+
+        $this->getJson(UserRepository::route(query: ['group_by' => 'name']))->assertJsonCount(2, 'data');
+    }
+
+    public function test_it_can_group_by_the_results_multiple_columns(): void
+    {
+        User::factory(3)->create([
+            'name' => 'John Doe',
+            'avatar' => 'image.jpg',
+        ]);
+
+        User::factory(1)->create([
+            'name' => 'Another John Doe',
+            'avatar' => 'image.jpg',
+        ]);
+
+        UserRepository::$groupBy = ['name', 'avatar'];
+
+        $this->getJson(UserRepository::route(query: ['group_by' => 'name,avatar']))->assertJsonCount(2, 'data');
+    }
+
+    public function test_it_can_not_group_by_the_results_because_wrong_column(): void
+    {
+        User::factory(4)->create([
+            'name' => 'John Doe',
+        ]);
+
+        User::factory(4)->create([
+            'name' => 'Second John Doe',
+        ]);
+
+        UserRepository::$groupBy = ['email'];
+
+        $this->getJson(UserRepository::route(query: ['group_by' => 'name']))->assertUnprocessable();
+    }
+}