[2.x] Add initial props resolver for Initial Page Load

src/Inertia.php

@@ -14,6 +14,7 @@
  * @method static void version(\Closure|string|null $version)
  * @method static string getVersion()
  * @method static void resolveUrlUsing(\Closure|null $urlResolver = null)
+ * @method static void resolveInitialProps(\Closure|null $initialPropsResolver = null)
  * @method static \Inertia\OptionalProp optional(callable $callback)
  * @method static \Inertia\LazyProp lazy(callable $callback)
  * @method static \Inertia\DeferProp defer(callable $callback, string $group = 'default')

src/Middleware.php

@@ -75,6 +75,16 @@ public function urlResolver()
         return null;
     }
 
+    /**
+     * Defines the initial props that are shared by default.
+     *
+     * @return \Closure|null
+     */
+    public function initialPropsResolver()
+    {
+        return null;
+    }
+
     /**
      * Handle the incoming request.
      *
@@ -93,6 +103,10 @@ public function handle(Request $request, Closure $next)
             Inertia::resolveUrlUsing($urlResolver);
         }
 
+        if ($initialPropsResolver = $this->initialPropsResolver()) {
+            Inertia::resolveInitialPropsUsing($initialPropsResolver);
+        }
+
         $response = $next($request);
         $response->headers->set('Vary', Header::INERTIA);
 

src/Response.php

@@ -81,6 +81,11 @@ class Response implements Responsable
      */
     protected ?Closure $urlResolver = null;
 
+    /**
+     * The initial props resolver callback.
+     */
+    protected ?Closure $initialPropsResolver = null;
+
     /**
      * Create a new Inertia response instance.
      *
@@ -92,7 +97,8 @@ public function __construct(
         string $rootView = 'app',
         string $version = '',
         bool $encryptHistory = false,
-        ?Closure $urlResolver = null
+        ?Closure $urlResolver = null,
+        ?Closure $initialPropsResolver = null,
     ) {
         $this->component = $component;
         $this->props = $props;
@@ -101,6 +107,7 @@ public function __construct(
         $this->clearHistory = session()->pull('inertia.clear_history', false);
         $this->encryptHistory = $encryptHistory;
         $this->urlResolver = $urlResolver;
+        $this->initialPropsResolver = $initialPropsResolver;
     }
 
     /**
@@ -188,6 +195,7 @@ public function toResponse($request)
             $this->resolveMergeProps($request),
             $this->resolveDeferredProps($request),
             $this->resolveCacheDirections($request),
+            $this->resolveInitialProps($request),
         );
 
         if ($request->header(Header::INERTIA)) {
@@ -508,6 +516,26 @@ public function resolveDeferredProps(Request $request): array
         return $deferredProps->isNotEmpty() ? ['deferredProps' => $deferredProps->toArray()] : [];
     }
 
+    /**
+     * Resolve initial props.
+     *
+     * @return array<string, mixed>
+     */
+    public function resolveInitialProps(Request $request): array
+    {
+        if ($request->header(Header::INERTIA)) {
+            return [];
+        }
+
+        if ($this->initialPropsResolver === null) {
+            return [];
+        }
+
+        $initialProps = App::call($this->initialPropsResolver, ['request' => $request]);
+
+        return empty($initialProps) ? [] : ['initialProps' => $initialProps];
+    }
+
     /**
      * Determine if the request is a partial request.
      */

src/ResponseFactory.php

@@ -61,6 +61,13 @@ class ResponseFactory
      */
     protected $urlResolver;
 
+    /**
+     * The initial props resolver callback.
+     *
+     * @var Closure|null
+     */
+    protected $initialPropsResolver;
+
     /**
      * Set the root view template for Inertia responses. This template
      * serves as the HTML wrapper that contains the Inertia root element
@@ -149,6 +156,14 @@ public function resolveUrlUsing(?Closure $urlResolver = null): void
         $this->urlResolver = $urlResolver;
     }
 
+    /**
+     * Set the initial props resolver.
+     */
+    public function resolveInitialPropsUsing(?Closure $initialPropsResolver = null): void
+    {
+        $this->initialPropsResolver = $initialPropsResolver;
+    }
+
     /**
      * Clear the browser history on the next visit.
      */
@@ -262,6 +277,7 @@ public function render(string $component, $props = []): Response
             $this->getVersion(),
             $this->encryptHistory ?? config('inertia.history.encrypt', false),
             $this->urlResolver,
+            $this->initialPropsResolver,
         );
     }
 

tests/InitialPropTest.php

@@ -0,0 +1,44 @@
+<?php
+
+namespace Inertia\Tests;
+
+use Illuminate\Session\Middleware\StartSession;
+use Illuminate\Support\Facades\Route;
+use Inertia\Inertia;
+use Inertia\Tests\Stubs\CustomInitialPropsResolverMiddleware;
+use Inertia\Tests\Stubs\ExampleMiddleware;
+
+class InitialPropTest extends TestCase
+{
+    public function test_initial_props_accessibility(): void
+    {
+        $this->prepareMockEndpoint();
+
+        $response = $this->withoutExceptionHandling()->get('/');
+
+        $response->assertSuccessful();
+        $this->assertSame(
+            '<div id="app" data-page="{&quot;component&quot;:&quot;User\/Edit&quot;,&quot;props&quot;:{&quot;errors&quot;:{}},&quot;url&quot;:&quot;\/&quot;,&quot;version&quot;:&quot;&quot;,&quot;clearHistory&quot;:false,&quot;encryptHistory&quot;:false,&quot;initialProps&quot;:{&quot;initial&quot;:true,&quot;appName&quot;:&quot;test&quot;}}"></div>',
+            $response->content(),
+        );
+    }
+
+    public function test_initial_props_are_not_accessible(): void
+    {
+        $this->prepareMockEndpoint();
+
+        $response = $this->withoutExceptionHandling()->get('/', [
+            'X-Inertia' => 'true',
+        ]);
+
+        $response->assertSuccessful();
+        $response->assertJsonMissingPath('initialProps');
+    }
+
+    private function prepareMockEndpoint(): \Illuminate\Routing\Route
+    {
+        return Route::middleware([StartSession::class, ExampleMiddleware::class, CustomInitialPropsResolverMiddleware::class])->get('/', function () {
+            return Inertia::render('User/Edit');
+        });
+    }
+}

tests/Stubs/CustomInitialPropsResolverMiddleware.php

@@ -0,0 +1,24 @@
+<?php
+
+namespace Inertia\Tests\Stubs;
+
+use Illuminate\Http\Request;
+use Illuminate\Routing\ResponseFactory;
+use Inertia\Middleware;
+use PHPUnit\Framework\Assert;
+
+class CustomInitialPropsResolverMiddleware extends Middleware
+{
+    public function initialPropsResolver(): callable
+    {
+        return function ($request, ResponseFactory $otherDependency) {
+            Assert::assertInstanceOf(Request::class, $request);
+            Assert::assertInstanceOf(ResponseFactory::class, $otherDependency);
+
+            return [
+                'initial' => true,
+                'appName' => 'test',
+            ];
+        };
+    }
+}