php 致命错误：调用未定义的方法 Database::prepare()
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Fatal error: Call to undefined method Database::prepare()
提问by user2460790
I have created a separate class for database and users.
我为数据库和用户创建了一个单独的类。
Database.php
数据库.php
class Database{
private $db;
public function __construct(){
/*** mysql hostname ***/
$hostname = 'localhost';
/*** mysql username ***/
$username = 'username_web';
/*** mysql password ***/
$password = 'password_web';
try {
$this->db = new PDO("mysql:host=$hostname;dbname=kamadhenu_web", $username, $password);
/*** echo a message saying we have connected ***/
}
catch(PDOException $e)
{
echo $e->getMessage();
}
}
/*** Query Function ***/
public function query($sql)
{
return $this->db->query($sql);
}
}
Users.php
用户.php
class Users{
private $db;
public function __construct($database) {
$this->db = $database;
}
public function login($username, $password)
{
$query=$this->db->prepare("SELECT `password`, `id` FROM `users` WHERE `username` = ?");
$query->bindValue(1, $username);
try{
$query->execute();
$data = $query->fetch();
$stored_password = $data['password'];
$id = $data['id'];
#hashing the supplied password and comparing it with the stored hashed password.
if($stored_password === sha1($password)){
return $id;
}else{
return false;
}
}catch(PDOException $e){
die($e->getMessage());
}
}
}
Here is my Login page with username and password.
这是我的登录页面，其中包含用户名和密码。
login.php
include('database.php');
include('users.php');
$dbh= new Database();
$users= new Users($dbh);
if (isset($_POST['submit']))
{
$username= $_POST['username'];
$password= $_POST['password'];
$login = $users->login($username, $password);
if ($login === false) {
$errors[] = 'Sorry, that username/password is invalid';
}
else {
// username/password is correct and the login method of the $users object returns the user's id, which is stored in $login.
$_SESSION['id'] = $login; // The user's id is now set into the user's session in the form of $_SESSION['id']
#Redirect the user to home.php.
header('Location: list-updates.php');
exit();
}
}
When I execute I get an error:
当我执行时，我收到一个错误：
Call to undefined method Database::prepare()
调用未定义的方法 Database::prepare()
回答by Cristian Bitoi
You create $dbhwhen you instantiate Database(), but instantiating the Database only returns an instance of your Database class, not your db connection. You should have a getDb to get your connection from database object:
您$dbh在实例化 Database() 时创建，但实例化 Database 仅返回 Database 类的实例，而不是您的 db 连接。您应该有一个 getDb 从数据库对象获取连接：
$dbClass = new Database();
$dbh = $dbClass->getDb(); // here you get the connection
$users= new Users($dbh); // here you give to Users() the $dbh, that isn't your
// connection.. it's just Database class
Database construct only return an instance of your Database class, not your db connection
数据库构造只返回数据库类的实例，而不是数据库连接
class Database{
private $db;
public function __construct(){
try {
$this->db = new PDO("mysql:host=$hostname;dbname=kamadhenu_web", $username, $password);
/*** echo a message saying we have connected ***/
}
catch(PDOException $e)
{
echo $e->getMessage();
}
}
public function getDb() {
if ($this->db instanceof PDO) {
return $this->db;
}
}
}
回答by Houssem Cherif
add the method "getmyDB" to database file
将方法“getmyDB”添加到数据库文件中
class Database
{
/* Properties */
private $conn;
private $dsn = 'mysql:dbname=test;host=127.0.0.1';
private $user = 'root';
private $password = '';
/* Creates database connection */
public
function __construct()
{
try
{
$this->conn = new PDO($this->dsn, $this->user, $this->password);
}
catch(PDOException $e)
{
print "Error!: " . $e->getMessage() . "";
die();
}
return $this->conn;
}
public function getmyDB()
{
if ($this->conn instanceof PDO)
{
return $this->conn;
}
}
}
and call it when you create the constructor in the file user.php
并在文件 user.php 中创建构造函数时调用它
include "database.php";
class User
{
/* Properties */
private $conn;
/* Get database access */
public
function __construct()
{
$this->conn = new Database();
$this->conn = $this->conn->getmyDB();
}
/* Login a user */
public
function login()
{
$stmt = $this->conn->prepare("SELECT username, usermail FROM user");
if ($stmt->execute())
{
while ($rows = $stmt->fetch())
{
$fetch[] = $rows;
}
return $fetch;
}
else
{
return false;
}
}
}
and finally add test.php file
最后添加 test.php 文件
include "user.php";
$user = new User();
$list = $user->login();
foreach($list as $test)
{
echo $test["username"];
}
回答by vikingmaster
Your Databaseclass does not extend PDO neither it does implement prepare method.
您的Database类既不扩展 PDO 也不实现prepare method。
In order to access your PDOobject, you must make it public and access like:
为了访问您的PDO对象，您必须将其设为公开并像这样访问：
From Userclass:
从User班级：
$this->db->db->prepare();
$this->db->db->prepare();
The best way would be to extend the PDOclass.
最好的方法是扩展PDO类。
