我正在编写一个自定义插件（定制，用于1个客户端，不用于发布和一般消费），需要访问自定义表。

一般来说，对于WP，我遵循的原则是在可能的情况下使用更高级别的API，因此很少需要使用\\wpdb。现在我确实有了需求，我发现它是多么古老！

通过查看源代码，我似乎可以确定它使用的是mysqli（因为插件需要php 7.1，我们也控制服务器），所以我想为什么不将其用于我的自定义表逻辑？

我写了一个小包装：

<?php

namespace PluginNamespaceHere\\DB;

use mysqli;
use wpdb;

/**
 * A small wrapper class that contains, and provides direct access to, the $wpdb object,
 * as well as the underlying MYSQLI object, so we can do real prepared statements etc
 */
class DB
{

    /** @var wpdb */
    public $wpdb;

    /** @var mysqli */
    public $mysqli;

    /**
     * @param wpdb $wpdb
     */
    public function __construct(wpdb $wpdb)
    {
        $this->wpdb = $wpdb;
        //$wpdb is protected, but accessible via magic __get() wp-db.php line: 643
        $this->mysqli = $wpdb->dbh;
    }


    /**
     * Run an SQL query. If $params are provided, prepared statements are used. If $bind_types are provided, they will be
     * used in the prepared statement, if not, all params will be treated as strings
     *
     * @param string $sql The SQL string, unprefixed table names should be wrapped in curly braces eg SELECT * FROM {posts}
     * @param array $params Optional parameters for prepared statements
     * @param string $bind_types Optional bind types for prepared statements, defaults to string
     * @retun bool|mysqli_result
     */
    public function run($sql, $params=[], $bind_types=\'\')
    {
        $sql = $this->prefixTableNamesInSqlString($sql);

        if(!is_array($params) || empty($params)){
            return $this->mysqli->query($sql);
        }
        if($bind_types == \'\'){
            $bind_types = str_repeat("s", count($params));
        }
        $stmt = $this->mysqli->prepare($sql);
        $stmt->bind_param($bind_types, ...$params);
        $stmt->execute();
        return $stmt->get_result();
    }

    /**
     * Replaces curly brace table names with their actual, prefixed name
     * Eg "SELECT * from {table_name}" => "SELECT * from wp_table_name"
     * @param string $sql
     * @return string
     */
    private function prefixTableNamesInSqlString($sql)
    {
        return str_replace(["{", "}"], [$this->wpdb->prefix, ""], $sql);
    }

}

这将允许我使用真正准备好的查询，并具有良好的可读性代码，如：

<?php
$sql = "
            SELECT DISTINCT c.ID AS course_id, c.post_title AS course_title
            FROM {posts} c
            JOIN {tmsc_course_product} cp
            ON c.id = cp.course_id
            WHERE cp.product_id IN(?,?)
        ";
//Yes, i know DB::run() can return bool! Out of scope for this question
$courses = $db->run($sql, [57,4761])->fetch_all(MYSQLI_ASSOC);

我唯一担心的是，这是否会对wpdb及其家属产生连锁效应。wpdb类并不容易阅读，而且似乎包含很多状态。