将自定义函数添加到 Laravel 查询构建器

Question

我正在尝试将 USE INDEX() 添加到 Laravel 中的查询构建器。我尝试按照与 link 类似的步骤进行操作并且有点成功，但我无法管理最后一点，我不确定我的临时代码是否创建了一个巨大的后门。

目标：我练习的目标是将索引添加到查询构建器，如下所示：

DB::table('users')->where('id',1)->**useIndex**('users')->get()->first();

这里有一个选项 useIndex 指定我要用于此查询的索引。

我还做了什么：在 App/Override

中创建了一个名为 Connection 的 class

   <?php
    
    namespace App\Override;
    class Connection extends \Illuminate\Database\MySqlConnection {
        //@Override
        public function query() {
            return new QueryBuilder(
                $this,
                $this->getQueryGrammar(),
                $this->getPostProcessor()
            );
        }
    }

在 App/Providers 中创建了一个名为 CustomDatabaseServiceProvider 的服务提供商。这里我只是操作了 registerConnectionServices 函数。我进一步评论 Illuminate\Database\DatabaseServiceProvider::class, 并在配置目录中将 App\Providers\CustomDatabaseServiceProvider::class, 添加到 app.php。

<?php

namespace App\Providers;

use App\Override\Connection;
use Illuminate\Database\DatabaseManager;
use Illuminate\Database\Query\Grammars\Grammar;
use Illuminate\Database\Schema;
use Illuminate\Contracts\Queue\EntityResolver;
use Illuminate\Database\Connectors\ConnectionFactory;
use Illuminate\Database\Eloquent\Factory as EloquentFactory;
use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\QueueEntityResolver;
use Illuminate\Support\ServiceProvider;

class CustomDatabaseServiceProvider extends ServiceProvider
{
    /**
     * The array of resolved Faker instances.
     *
     * @var array
     */
    protected static $fakers = [];

    /**
     * Bootstrap the application events.
     *
     * @return void
     */
    public function boot()
    {
        Model::setConnectionResolver($this->app['db']);

        Model::setEventDispatcher($this->app['events']);
    }

    /**
     * Register the service provider.
     *
     * @return void
     */
    public function register()
    {
        Model::clearBootedModels();

        $this->registerConnectionServices();

        $this->registerEloquentFactory();

        $this->registerQueueableEntityResolver();
    }

    /**
     * Register the primary database bindings.
     *
     * @return void
     */
    protected function registerConnectionServices()
    {
        // The connection factory is used to create the actual connection instances on
        // the database. We will inject the factory into the manager so that it may
        // make the connections while they are actually needed and not of before.
        $this->app->singleton('db.factory', function ($app) {
            return new ConnectionFactory($app);
        });

        // The database manager is used to resolve various connections, since multiple
        // connections might be managed. It also implements the connection resolver
        // interface which may be used by other components requiring connections.
        $this->app->singleton('db', function ($app) {
            $dbm = new DatabaseManager($app, $app['db.factory']);
            //Extend to include the custom connection (MySql in this example)
            $dbm->extend('mysql', function ($config, $name) use ($app) {
                //Create default connection from factory
                $connection = $app['db.factory']->make($config, $name);
                //Instantiate our connection with the default connection data
                $new_connection = new Connection(
                    $connection->getPdo(),
                    $connection->getDatabaseName(),
                    $connection->getTablePrefix(),
                    $config
                );
                //Set the appropriate grammar object
//                $new_connection->setQueryGrammar(new Grammar());
//                $new_connection->setSchemaGrammar(new Schema\());
                return $new_connection;
            });
            return $dbm;
        });

        $this->app->bind('db.connection', function ($app) {
            return $app['db']->connection();
        });
    }

    /**
     * Register the Eloquent factory instance in the container.
     *
     * @return void
     */
    protected function registerEloquentFactory()
    {
        $this->app->singleton(FakerGenerator::class, function ($app, $parameters) {
            $locale = $parameters['locale'] ?? $app['config']->get('app.faker_locale', 'en_US');

            if (!isset(static::$fakers[$locale])) {
                static::$fakers[$locale] = FakerFactory::create($locale);
            }

            static::$fakers[$locale]->unique(true);

            return static::$fakers[$locale];
        });

        $this->app->singleton(EloquentFactory::class, function ($app) {
            return EloquentFactory::construct(
                $app->make(FakerGenerator::class), $this->app->databasePath('factories')
            );
        });
    }

    /**
     * Register the queueable entity resolver implementation.
     *
     * @return void
     */
    protected function registerQueueableEntityResolver()
    {
        $this->app->singleton(EntityResolver::class, function () {
            return new QueueEntityResolver;
        });
    }
}

并最终在 App/Override 中创建了一个名为 QueryBuilder 的 class。这是有问题的 class:

<?php

namespace App\Override;

use Illuminate\Support\Facades\Cache;

class QueryBuilder extends \Illuminate\Database\Query\Builder
{
    private $Index = [];

    public function useIndex($index = null)
    {
        $this->Index = $index;
        return $this;
    }

    //@Override
    public function get($columns = ['*'])
    {
        if ($this->Index) {
            //Get the raw query string with the PDO bindings
            $sql_str = str_replace('from `' . $this->from . '`', 'from `' . $this->from . '` USE INDEX (`' . $this->Index . '`) ', $this->toSql());
            $sql_str = vsprintf($sql_str, $this->getBindings());
            return parent::get($sql_str);
        } else {
            //Return default
            return parent::get($columns);
        }
    }
}

这里的问题是：

输出不包含USE INDEX
使用str_replace操作查询是否安全？

Answer 1

查询生成器是可宏化的，因此在您的服务提供商中您可以这样做：

Illuminate\Database\Query\Builder::macro(
    'tableWithIndex',
    function ($table, $index) {
        $table = $this->grammar->wrapTable($table);
        $index = $this->grammar->wrap($index);
        return $this->fromRaw("$table USE INDEX ($index)");
    }
);

那么你可以使用这个：

DB::tableWithIndex('users', 'users');

在宏 $this 中将引用查询生成器实例

请注意，我将它们合二为一，因为您可能会对同一个查询进行多次 from 调用，而试图弄清楚哪里发生了什么会很麻烦

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