[2.x] Add initial Shared Prop Support for Initial Page Load

src/FirstLoad.php

@@ -0,0 +1,8 @@
+<?php
+
+namespace Inertia;
+
+interface FirstLoad
+{
+    //
+}

src/InitialProp.php

@@ -0,0 +1,20 @@
+<?php
+
+namespace Inertia;
+
+use Illuminate\Support\Facades\App;
+
+class InitialProp implements FirstLoad
+{
+    protected $callback;
+
+    public function __construct(callable $callback)
+    {
+        $this->callback = $callback;
+    }
+
+    public function __invoke()
+    {
+        return App::call($this->callback);
+    }
+}

src/Response.php

@@ -47,7 +47,7 @@ public function __construct(
         string $rootView = 'app',
         string $version = '',
         bool $encryptHistory = false,
-        ?Closure $urlResolver = null
+        ?Closure $urlResolver = null,
     ) {
         $this->component = $component;
         $this->props = $props instanceof Arrayable ? $props->toArray() : $props;
@@ -126,6 +126,7 @@ public function toResponse($request)
             $this->resolveMergeProps($request),
             $this->resolveDeferredProps($request),
             $this->resolveCacheDirections($request),
+            $this->resolveInitialProps($request),
         );
 
         if ($request->header(Header::INERTIA)) {
@@ -141,6 +142,7 @@ public function toResponse($request)
     public function resolveProperties(Request $request, array $props): array
     {
         $props = $this->resolvePartialProperties($props, $request);
+        $props = $this->filterInitialProps($props);
         $props = $this->resolveArrayableProperties($props, $request);
         $props = $this->resolveAlways($props);
         $props = $this->resolvePropertyInstances($props, $request);
@@ -296,6 +298,14 @@ public function resolvePropertyInstances(array $props, Request $request): array
         return $props;
     }
 
+    /**
+     * Filter initial properties from the props.
+     */
+    public function filterInitialProps(array $props): array
+    {
+        return array_filter($props, static fn ($prop) => ! $prop instanceof InitialProp);
+    }
+
     /**
      * Resolve the cache directions for the response.
      */
@@ -376,6 +386,19 @@ public function resolveDeferredProps(Request $request): array
         return $deferredProps->isNotEmpty() ? ['deferredProps' => $deferredProps->toArray()] : [];
     }
 
+    public function resolveInitialProps(Request $request): array
+    {
+        if ($request->header(Header::INERTIA)) {
+            return [];
+        }
+
+        $initialProps = collect($this->props)
+            ->filter(fn ($prop) => $prop instanceof InitialProp)
+            ->mapWithKeys(fn ($value, $key) => [$key => App::call($value)]);
+
+        return $initialProps->isNotEmpty() ? ['initialProps' => $initialProps->toArray()] : [];
+    }
+
     /**
      * Determine if the request is a partial request.
      */

src/ResponseFactory.php

@@ -35,9 +35,8 @@ class ResponseFactory
     /** @var Closure|null */
     protected $urlResolver;
 
-    /***
-     * @param string $name The name of the root view
-     * @return void
+    /**
+     * @param  string  $name  The name of the root view
      */
     public function setRootView(string $name): void
     {
@@ -128,6 +127,11 @@ public function optional(callable $callback): OptionalProp
         return new OptionalProp($callback);
     }
 
+    public function initial(callable $callback): InitialProp
+    {
+        return new InitialProp($callback);
+    }
+
     public function defer(callable $callback, string $group = 'default'): DeferProp
     {
         return new DeferProp($callback, $group);

tests/InitialPropTest.php

@@ -0,0 +1,73 @@
+<?php
+
+namespace Inertia\Tests;
+
+use Illuminate\Http\Request;
+use Illuminate\Session\Middleware\StartSession;
+use Illuminate\Support\Facades\Route;
+use Inertia\Inertia;
+use Inertia\InitialProp;
+use Inertia\Tests\Stubs\ExampleMiddleware;
+
+class InitialPropTest extends TestCase
+{
+    public function test_initial_props_accessibility()
+    {
+        Inertia::share([
+            'initial' => Inertia::initial(fn () => true),
+            'appName' => Inertia::initial(fn () => 'test'),
+        ]);
+
+        $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()
+    {
+        Inertia::share([
+            'initial' => Inertia::initial(fn () => true),
+            'appName' => Inertia::initial(fn () => 'test'),
+        ]);
+
+        $this->prepareMockEndpoint();
+
+        $response = $this->withoutExceptionHandling()->get('/', [
+            'X-Inertia' => 'true',
+        ]);
+
+        $response->assertSuccessful();
+        $response->assertJsonMissingPath('initialProps');
+    }
+
+    public function test_can_invoke(): void
+    {
+        $initialProp = new InitialProp(function () {
+            return 'A initial value';
+        });
+
+        $this->assertSame('A initial value', $initialProp());
+    }
+
+    public function test_can_resolve_bindings_when_invoked(): void
+    {
+        $initialProp = new InitialProp(function (Request $request) {
+            return $request;
+        });
+
+        $this->assertInstanceOf(Request::class, $initialProp());
+    }
+
+    private function prepareMockEndpoint(): \Illuminate\Routing\Route
+    {
+        return Route::middleware([StartSession::class, ExampleMiddleware::class])->get('/', function () {
+            return Inertia::render('User/Edit');
+        });
+    }
+}

tests/ResponseFactoryTest.php

@@ -15,6 +15,7 @@
 use Inertia\ComponentNotFoundException;
 use Inertia\DeferProp;
 use Inertia\Inertia;
+use Inertia\InitialProp;
 use Inertia\LazyProp;
 use Inertia\MergeProp;
 use Inertia\OptionalProp;
@@ -342,6 +343,16 @@ public function test_can_create_optional_prop(): void
         $this->assertInstanceOf(OptionalProp::class, $optionalProp);
     }
 
+    public function test_can_create_initial_prop(): void
+    {
+        $factory = new ResponseFactory;
+        $initialProp = $factory->initial(function () {
+            return 'An initial value';
+        });
+
+        $this->assertInstanceOf(InitialProp::class, $initialProp);
+    }
+
     public function test_can_create_always_prop(): void
     {
         $factory = new ResponseFactory;