Automatically share validation errors

src/ServiceProvider.php

@@ -4,8 +4,10 @@
 
 use Illuminate\Http\Request;
 use Illuminate\Routing\Router;
+use Illuminate\Support\Collection;
 use Illuminate\Contracts\Http\Kernel;
 use Illuminate\Support\Facades\Blade;
+use Illuminate\Support\Facades\Session;
 use Illuminate\Support\ServiceProvider as BaseServiceProvider;
 
 class ServiceProvider extends BaseServiceProvider
@@ -21,6 +23,7 @@ public function boot()
         $this->registerRequestMacro();
         $this->registerRouterMacro();
         $this->registerMiddleware();
+        $this->shareValidationErrors();
     }
 
     protected function registerBladeDirective()
@@ -50,4 +53,25 @@ protected function registerMiddleware()
     {
         $this->app[Kernel::class]->pushMiddleware(Middleware::class);
     }
+
+    protected function shareValidationErrors()
+    {
+        if (Inertia::getShared('errors')) {
+            return;
+        }
+
+        Inertia::share('errors', function () {
+            if (! Session::has('errors')) {
+                return (object) [];
+            }
+
+            return (object) Collection::make(Session::get('errors')->getBags())->map(function ($bag) {
+                return (object) Collection::make($bag->messages())->map(function ($errors) {
+                    return $errors[0];
+                })->toArray();
+            })->pipe(function ($bags) {
+                return $bags->has('default') ? $bags->get('default') : $bags->toArray();
+            });
+        });
+    }
 }

tests/ControllerTest.php

@@ -28,7 +28,10 @@ public function test_controller_returns_an_inertia_response()
         $this->assertEquals([
             'page' => [
                 'component' => 'User/Edit',
-                'props' => ['user' => ['name' => 'Jonathan']],
+                'props' => [
+                    'user' => ['name' => 'Jonathan'],
+                    'errors' => (object) [],
+                ],
                 'url' => '',
                 'version' => null,
             ],

tests/ServiceProviderTest.php

@@ -2,12 +2,17 @@
 
 namespace Inertia\Tests;
 
+use Closure;
+use Inertia\Inertia;
 use Inertia\Middleware;
 use Illuminate\Http\Request;
+use Illuminate\Support\MessageBag;
 use Illuminate\Support\Facades\App;
+use Illuminate\Support\ViewErrorBag;
 use Illuminate\Contracts\Http\Kernel;
 use Illuminate\Support\Facades\Blade;
 use Illuminate\Support\Facades\Route;
+use Illuminate\Support\Facades\Session;
 
 class ServiceProviderTest extends TestCase
 {
@@ -49,4 +54,52 @@ public function test_middleware_is_registered()
 
         $this->assertTrue($kernel->hasMiddleware(Middleware::class));
     }
+
+    public function test_validation_errors_are_registered()
+    {
+        $this->assertInstanceOf(Closure::class, Inertia::getShared('errors'));
+    }
+
+    public function test_validation_errors_can_be_empty()
+    {
+        $errors = Inertia::getShared('errors')();
+
+        $this->assertIsObject($errors);
+        $this->assertEmpty(get_object_vars($errors));
+    }
+
+    public function test_validation_errors_are_not_registered_when_already_registered()
+    {
+        Inertia::share('errors', 'This is a validation error');
+
+        $this->assertSame('This is a validation error', Inertia::getShared('errors'));
+    }
+
+    public function test_validation_errors_are_returned_in_the_correct_format()
+    {
+        Session::put('errors', (new ViewErrorBag())->put('default', new MessageBag([
+            'name' => 'The name field is required.',
+            'email' => 'Not a valid email address.',
+        ])));
+
+        $errors = Inertia::getShared('errors')();
+
+        $this->assertIsObject($errors);
+        $this->assertSame('The name field is required.', $errors->name);
+        $this->assertSame('Not a valid email address.', $errors->email);
+    }
+
+    public function test_validation_errors_with_named_error_bags_are_scoped()
+    {
+        Session::put('errors', (new ViewErrorBag())->put('example', new MessageBag([
+            'name' => 'The name field is required.',
+            'email' => 'Not a valid email address.',
+        ])));
+
+        $errors = Inertia::getShared('errors')();
+
+        $this->assertIsObject($errors);
+        $this->assertSame('The name field is required.', $errors->example->name);
+        $this->assertSame('Not a valid email address.', $errors->example->email);
+    }
 }