oop不能讓這個小腳本正常登錄工作

Question

我不明白爲什麼這不起作用。我是新的，只是學習。

的login.php

<?php 

    include 'core/init.php'; 

    if (empty($_POST) === false) { 
     $username = $_POST['username']; 
     $password = $_POST['password']; 

     $user = new User(); 

     if (empty($username) === true || empty($password) === true) { 
      echo 'you need to enter a username and password'; 
     } else if ($user->userExists($username) === false) { 
      echo 'we cant find that username. have you registered?'; 
     } else echo 'ok'; 
    } 

    ?>  <?php 

    include 'core/init.php'; 

    if (empty($_POST) === false) { 
     $username = $_POST['username']; 
     $password = $_POST['password']; 

     $user = new User(); 

     if (empty($username) === true || empty($password) === true) { 
      echo 'you need to enter a username and password'; 
     } else if ($user->userExists($username) === false) { 
      echo 'we cant find that username. have you registered?'; 
     } else echo 'ok'; 
    } 

    ?>  <?php 

    include 'core/init.php'; 

    if (empty($_POST) === false) { 
     $username = $_POST['username']; 
     $password = $_POST['password']; 

     $user = new User(); 

     if (empty($username) === true || empty($password) === true) { 
      echo 'you need to enter a username and password'; 
     } else if ($user->userExists($username) === false) { 
      echo 'we cant find that username. have you registered?'; 
     } else echo 'ok'; 
    } 

?> 

user.php的

<?php 
    require_once 'core/classes/Connect.php'; 

    class User { 

     private $db; 

     public function __construct() { 
      $this->db = new Connect(); 
      $this->db = $this->db->dbConnect(); 
     } 

     public function userExists($username) { 
      $st = $this->db->prepare("SELECT COUNT(user_id) FROM users WHERE username=?"); 
      $st->bindParam(1, $username); 
      $st->execute(); 

      if ($st->rowCount() == 1) { 
       return true; 
      } else return false;  
     }  
    } 
?> 

我一直特林學OOP，每個人都告訴我，最好的學習方法是嘗試，而不是尋求幫助。我打算建立一個簡單的登錄，然後使其更加複雜。

當我輸入正確的用戶名時，它不是echo ok。相反，它echo我們無法找到該用戶名。你有沒有註冊？請任何幫助。謝謝

Answer 1

我不知道你的Connect類（尤其是方法rowCount）是如何工作的，但問題似乎如下：你的查詢返回給定用戶名的user_id數目，但你計數行。

更換

$st = $this->db->prepare("SELECT COUNT(user_id) FROM users WHERE username=?"); 

與

$st = $this->db->prepare("SELECT user_id FROM users WHERE username=?"); 

應該做的伎倆。

而且因爲你正在學習一些更多的評論：

empty($username) === true等於empty($username)。大多數程序員更喜歡後者（因爲它更短）。

另外，將方法userExists聲明爲靜態似乎更有意義。