php - 使用 PDO 对 null 调用成员函数 query()

Question

我刚刚检查了 stackoverflow 上提供的所有答案，它们很相似，但不完全是我的答案。因此，请不要将此帖子视为重复。

这些是我执行时的代码

Fatal error: Call to a member function query() on null in C:\wamp64\www\ourCMS\index.php on line 12

这是我的片段:

<?php

class DB
{
    private $dbHost;
    private $dbName;
    private $dbUser;
    private $dbPass;

    protected $con;

    function set_db($host, $db, $user, $pass)
    {
        $this->dbHost = $host;
        $this->dbName = $db;
        $this->dbUser = $user;
        $this->dbPass = $pass;

    }

    function connect()
    {
        $info = 'mysql:host='.$this->dbHost.';dbname='.$this->dbName;
        try
        {
            $this->con = new PDO($info, $this->dbUser, $this->dbPass);
        }
        catch(PDOException $e)
        {
            print "Error Founds: ".$e->getMessage().PHP_EOL;
            die();
        }
    }
}

// here is the place where i'm trying to use this actually
if (isset($_POST['submit']))
{
    include('include/database.php');

    $database = new DB;
    $database->set_db("localhost", "ourcms", "root", "");
    $conn = $database->connect();

    $name = $_POST['nm'];
    $query = "INSERT INTO testingpdo (name) VALUES ('$name')";
    $data = $conn->query($query);
    $result = $data->fetchAll(PDO::FETCH_ASSOC);

    print_r($result);
}

Answer 1

您不会从 DB::connect ($conn = $database->connect();) 返回任何内容。在函数末尾添加 return $this->con;。

function connect()
{
    $info = 'mysql:host='.$this->dbHost.';dbname='.$this->dbName;
    try
    {
        $this->con = new PDO($info, $this->dbUser, $this->dbPass);
    }
    catch(PDOException $e)
    {
        print "Error Founds: ".$e->getMessage().PHP_EOL;
        die();
    }
    return $this->con;
}