Bài này dịch từ bài này ;)

Khi làm việc với laravel, chắc hẳn bạn dùng rất nhiều đoạn code này. Nó rất tiện lợi trong việc trả về một view sau khi controller thực thi các tác vụ liên quan đến business requirement.

return view('a/b/c.d.e.f', ['param' => $value]);

Tuy nhiên, nó làm việc thế nào, hơi bị ảo đúng không nhỉ? Cùng đào sâu tìm hiểu thử xem thế nào? :)

Đây là tài liệu từ laravel về views: https://laravel.com/docs/master/views

Nhưng mình nghĩ nó không đầy đủ lắm, đào sâu xem coi thử nó chạy sao nhỉ?

Đầu tiên, laravel có hàm view được viết trong file helpers.php. Đây là file helpers

Illuminate\Foundation\helpers.php

function view($view = null, $data = [], $mergeData = [])
    {
        $factory = app(ViewFactory::class);

        if (func_num_args() === 0) {
            return $factory;
        }

        return $factory->make($view, $data, $mergeData);
    }

Mình nghĩ ,có 2 thứ cần xem xét ở đây

1. $factory = app(ViewFactory::class);

2. return $factory->make($view, $data, $mergeData);

Đầu tiên (tiền đâu) là $factory = app(ViewFactory::class);

Thực ra, nó tạo ra một thực thể $factory (và được inject vào thực thể $app). Khi ứng dụng được khởi tạo thì nó sẽ gọi hàm registerCoreContainerAliases (github code).

Cùng xem thử hàm registerCoreContainerAliases xem sao nhé

/**
     * Register the core class aliases in the container.
     *
     * @return void
     */
    public function registerCoreContainerAliases()
    {
        $aliases = [
            'app'                  => ['Illuminate\Foundation\Application', 'Illuminate\Contracts\Container\Container', 'Illuminate\Contracts\Foundation\Application'],
            'auth'                 => ['Illuminate\Auth\AuthManager', 'Illuminate\Contracts\Auth\Factory'],
            'auth.driver'          => ['Illuminate\Contracts\Auth\Guard'],
            'blade.compiler'       => ['Illuminate\View\Compilers\BladeCompiler'],
            'cache'                => ['Illuminate\Cache\CacheManager', 'Illuminate\Contracts\Cache\Factory'],
            'cache.store'          => ['Illuminate\Cache\Repository', 'Illuminate\Contracts\Cache\Repository'],
            'config'               => ['Illuminate\Config\Repository', 'Illuminate\Contracts\Config\Repository'],
            'cookie'               => ['Illuminate\Cookie\CookieJar', 'Illuminate\Contracts\Cookie\Factory', 'Illuminate\Contracts\Cookie\QueueingFactory'],
            'encrypter'            => ['Illuminate\Encryption\Encrypter', 'Illuminate\Contracts\Encryption\Encrypter'],
            'db'                   => ['Illuminate\Database\DatabaseManager'],
            'db.connection'        => ['Illuminate\Database\Connection', 'Illuminate\Database\ConnectionInterface'],
            'events'               => ['Illuminate\Events\Dispatcher', 'Illuminate\Contracts\Events\Dispatcher'],
            'files'                => ['Illuminate\Filesystem\Filesystem'],
            'filesystem'           => ['Illuminate\Filesystem\FilesystemManager', 'Illuminate\Contracts\Filesystem\Factory'],
            'filesystem.disk'      => ['Illuminate\Contracts\Filesystem\Filesystem'],
            'filesystem.cloud'     => ['Illuminate\Contracts\Filesystem\Cloud'],
            'hash'                 => ['Illuminate\Contracts\Hashing\Hasher'],
            'translator'           => ['Illuminate\Translation\Translator', 'Symfony\Component\Translation\TranslatorInterface'],
            'log'                  => ['Illuminate\Log\Writer', 'Illuminate\Contracts\Logging\Log', 'Psr\Log\LoggerInterface'],
            'mailer'               => ['Illuminate\Mail\Mailer', 'Illuminate\Contracts\Mail\Mailer', 'Illuminate\Contracts\Mail\MailQueue'],
            'auth.password'        => ['Illuminate\Auth\Passwords\PasswordBrokerManager', 'Illuminate\Contracts\Auth\PasswordBrokerFactory'],
            'auth.password.broker' => ['Illuminate\Auth\Passwords\PasswordBroker', 'Illuminate\Contracts\Auth\PasswordBroker'],
            'queue'                => ['Illuminate\Queue\QueueManager', 'Illuminate\Contracts\Queue\Factory', 'Illuminate\Contracts\Queue\Monitor'],
            'queue.connection'     => ['Illuminate\Contracts\Queue\Queue'],
            'redirect'             => ['Illuminate\Routing\Redirector'],
            'redis'                => ['Illuminate\Redis\Database', 'Illuminate\Contracts\Redis\Database'],
            'request'              => ['Illuminate\Http\Request', 'Symfony\Component\HttpFoundation\Request'],
            'router'               => ['Illuminate\Routing\Router', 'Illuminate\Contracts\Routing\Registrar'],
            'session'              => ['Illuminate\Session\SessionManager'],
            'session.store'        => ['Illuminate\Session\Store', 'Symfony\Component\HttpFoundation\Session\SessionInterface'],
            'url'                  => ['Illuminate\Routing\UrlGenerator', 'Illuminate\Contracts\Routing\UrlGenerator'],
            'validator'            => ['Illuminate\Validation\Factory', 'Illuminate\Contracts\Validation\Factory'],
            'view'                 => ['Illuminate\View\Factory', 'Illuminate\Contracts\View\Factory'],
        ];
 
        foreach ($aliases as $key => $aliases) {
            foreach ($aliases as $alias) {
                $this->alias($key, $alias);
            }
        }
    }

Để ý rằng view là alias, bạn có thể đặt bất kỳ cái tên nào khác tùy ý (vd: myView, viewCuaTao, etc …)

Sau đó trong file Illuminate\View\ViewServiceProvider.php, xem thử hàm registerFactory

/**
     * Register the core class aliases in the container.
     *
     * @return void
     */
    public function registerCoreContainerAliases()
    {
        $aliases = [
            'app'                  => ['Illuminate\Foundation\Application', 'Illuminate\Contracts\Container\Container', 'Illuminate\Contracts\Foundation\Application'],
            'auth'                 => ['Illuminate\Auth\AuthManager', 'Illuminate\Contracts\Auth\Factory'],
            'auth.driver'          => ['Illuminate\Contracts\Auth\Guard'],
            'blade.compiler'       => ['Illuminate\View\Compilers\BladeCompiler'],
            'cache'                => ['Illuminate\Cache\CacheManager', 'Illuminate\Contracts\Cache\Factory'],
            'cache.store'          => ['Illuminate\Cache\Repository', 'Illuminate\Contracts\Cache\Repository'],
            'config'               => ['Illuminate\Config\Repository', 'Illuminate\Contracts\Config\Repository'],
            'cookie'               => ['Illuminate\Cookie\CookieJar', 'Illuminate\Contracts\Cookie\Factory', 'Illuminate\Contracts\Cookie\QueueingFactory'],
            'encrypter'            => ['Illuminate\Encryption\Encrypter', 'Illuminate\Contracts\Encryption\Encrypter'],
            'db'                   => ['Illuminate\Database\DatabaseManager'],
            'db.connection'        => ['Illuminate\Database\Connection', 'Illuminate\Database\ConnectionInterface'],
            'events'               => ['Illuminate\Events\Dispatcher', 'Illuminate\Contracts\Events\Dispatcher'],
            'files'                => ['Illuminate\Filesystem\Filesystem'],
            'filesystem'           => ['Illuminate\Filesystem\FilesystemManager', 'Illuminate\Contracts\Filesystem\Factory'],
            'filesystem.disk'      => ['Illuminate\Contracts\Filesystem\Filesystem'],
            'filesystem.cloud'     => ['Illuminate\Contracts\Filesystem\Cloud'],
            'hash'                 => ['Illuminate\Contracts\Hashing\Hasher'],
            'translator'           => ['Illuminate\Translation\Translator', 'Symfony\Component\Translation\TranslatorInterface'],
            'log'                  => ['Illuminate\Log\Writer', 'Illuminate\Contracts\Logging\Log', 'Psr\Log\LoggerInterface'],
            'mailer'               => ['Illuminate\Mail\Mailer', 'Illuminate\Contracts\Mail\Mailer', 'Illuminate\Contracts\Mail\MailQueue'],
            'auth.password'        => ['Illuminate\Auth\Passwords\PasswordBrokerManager', 'Illuminate\Contracts\Auth\PasswordBrokerFactory'],
            'auth.password.broker' => ['Illuminate\Auth\Passwords\PasswordBroker', 'Illuminate\Contracts\Auth\PasswordBroker'],
            'queue'                => ['Illuminate\Queue\QueueManager', 'Illuminate\Contracts\Queue\Factory', 'Illuminate\Contracts\Queue\Monitor'],
            'queue.connection'     => ['Illuminate\Contracts\Queue\Queue'],
            'redirect'             => ['Illuminate\Routing\Redirector'],
            'redis'                => ['Illuminate\Redis\Database', 'Illuminate\Contracts\Redis\Database'],
            'request'              => ['Illuminate\Http\Request', 'Symfony\Component\HttpFoundation\Request'],
            'router'               => ['Illuminate\Routing\Router', 'Illuminate\Contracts\Routing\Registrar'],
            'session'              => ['Illuminate\Session\SessionManager'],
            'session.store'        => ['Illuminate\Session\Store', 'Symfony\Component\HttpFoundation\Session\SessionInterface'],
            'url'                  => ['Illuminate\Routing\UrlGenerator', 'Illuminate\Contracts\Routing\UrlGenerator'],
            'validator'            => ['Illuminate\Validation\Factory', 'Illuminate\Contracts\Validation\Factory'],
            'view'                 => ['Illuminate\View\Factory', 'Illuminate\Contracts\View\Factory'],
        ];
 
        foreach ($aliases as $key => $aliases) {
            foreach ($aliases as $alias) {
                $this->alias($key, $alias);
            }
        }
    }

Như đã đề cập ở trên, tên view này có thể là bất kỳ thứ quái gì, miễn là bạn đặt cùng tên trong 3 files (helpers.php, Application.php,ViewServiceProvider.php)

Thứ 2: return $factory->make($view, $data, $mergeData);

Cùng xem thử hàm make xem sao nào?

/**
     * Register the core class aliases in the container.
     *
     * @return void
     */
    public function registerCoreContainerAliases()
    {
        $aliases = [
            'app'                  => ['Illuminate\Foundation\Application', 'Illuminate\Contracts\Container\Container', 'Illuminate\Contracts\Foundation\Application'],
            'auth'                 => ['Illuminate\Auth\AuthManager', 'Illuminate\Contracts\Auth\Factory'],
            'auth.driver'          => ['Illuminate\Contracts\Auth\Guard'],
            'blade.compiler'       => ['Illuminate\View\Compilers\BladeCompiler'],
            'cache'                => ['Illuminate\Cache\CacheManager', 'Illuminate\Contracts\Cache\Factory'],
            'cache.store'          => ['Illuminate\Cache\Repository', 'Illuminate\Contracts\Cache\Repository'],
            'config'               => ['Illuminate\Config\Repository', 'Illuminate\Contracts\Config\Repository'],
            'cookie'               => ['Illuminate\Cookie\CookieJar', 'Illuminate\Contracts\Cookie\Factory', 'Illuminate\Contracts\Cookie\QueueingFactory'],
            'encrypter'            => ['Illuminate\Encryption\Encrypter', 'Illuminate\Contracts\Encryption\Encrypter'],
            'db'                   => ['Illuminate\Database\DatabaseManager'],
            'db.connection'        => ['Illuminate\Database\Connection', 'Illuminate\Database\ConnectionInterface'],
            'events'               => ['Illuminate\Events\Dispatcher', 'Illuminate\Contracts\Events\Dispatcher'],
            'files'                => ['Illuminate\Filesystem\Filesystem'],
            'filesystem'           => ['Illuminate\Filesystem\FilesystemManager', 'Illuminate\Contracts\Filesystem\Factory'],
            'filesystem.disk'      => ['Illuminate\Contracts\Filesystem\Filesystem'],
            'filesystem.cloud'     => ['Illuminate\Contracts\Filesystem\Cloud'],
            'hash'                 => ['Illuminate\Contracts\Hashing\Hasher'],
            'translator'           => ['Illuminate\Translation\Translator', 'Symfony\Component\Translation\TranslatorInterface'],
            'log'                  => ['Illuminate\Log\Writer', 'Illuminate\Contracts\Logging\Log', 'Psr\Log\LoggerInterface'],
            'mailer'               => ['Illuminate\Mail\Mailer', 'Illuminate\Contracts\Mail\Mailer', 'Illuminate\Contracts\Mail\MailQueue'],
            'auth.password'        => ['Illuminate\Auth\Passwords\PasswordBrokerManager', 'Illuminate\Contracts\Auth\PasswordBrokerFactory'],
            'auth.password.broker' => ['Illuminate\Auth\Passwords\PasswordBroker', 'Illuminate\Contracts\Auth\PasswordBroker'],
            'queue'                => ['Illuminate\Queue\QueueManager', 'Illuminate\Contracts\Queue\Factory', 'Illuminate\Contracts\Queue\Monitor'],
            'queue.connection'     => ['Illuminate\Contracts\Queue\Queue'],
            'redirect'             => ['Illuminate\Routing\Redirector'],
            'redis'                => ['Illuminate\Redis\Database', 'Illuminate\Contracts\Redis\Database'],
            'request'              => ['Illuminate\Http\Request', 'Symfony\Component\HttpFoundation\Request'],
            'router'               => ['Illuminate\Routing\Router', 'Illuminate\Contracts\Routing\Registrar'],
            'session'              => ['Illuminate\Session\SessionManager'],
            'session.store'        => ['Illuminate\Session\Store', 'Symfony\Component\HttpFoundation\Session\SessionInterface'],
            'url'                  => ['Illuminate\Routing\UrlGenerator', 'Illuminate\Contracts\Routing\UrlGenerator'],
            'validator'            => ['Illuminate\Validation\Factory', 'Illuminate\Contracts\Validation\Factory'],
            'view'                 => ['Illuminate\View\Factory', 'Illuminate\Contracts\View\Factory'],
        ];
 
        foreach ($aliases as $key => $aliases) {
            foreach ($aliases as $alias) {
                $this->alias($key, $alias);
            }
        }
    }

Nó sẽ trả về đối tượng View (\Illuminate\View\View)

new View($this, $this->getEngineFromPath($path), $view, $path, $data)

Đơn giản thế thôi (nếu không hiểu thì còm liền :v )

Nếu bạn có thắc mắc gì, vui lòng còm bên dưới.