在插入或從數據庫中選擇數據時在PHP中的錯誤

Question

我不斷收到錯誤未定義的索引在嘗試從我的Android應用程序登錄或註冊時在PHP中。我試圖更改PHP版本，但它沒有解決問題。以下是錯誤我得到的error_log：

[28-Aug-2017 15:15:33 America/Denver] PHP Notice: Undefined index: full_name in /home2/heratarm/public_html/socialnetwork-api/Classes/user.php on line 33 
[28-Aug-2017 15:15:33 America/Denver] PHP Notice: Undefined index: username in /home2/heratarm/public_html/socialnetwork-api/Classes/user.php on line 34 
[28-Aug-2017 15:15:33 America/Denver] PHP Notice: Undefined index: email in /home2/heratarm/public_html/socialnetwork-api/Classes/user.php on line 35 
[28-Aug-2017 15:15:33 America/Denver] PHP Notice: Undefined index: password in /home2/heratarm/public_html/socialnetwork-api/Classes/user.php on line 36 
[28-Aug-2017 15:15:57 America/Denver] PHP Notice: Undefined index: username in /home2/heratarm/public_html/socialnetwork-api/Classes/user.php on line 12 
[28-Aug-2017 15:15:57 America/Denver] PHP Notice: Undefined index: password in /home2/heratarm/public_html/socialnetwork-api/Classes/user.php on line 13 

，這裏是我的PHP代碼：

class user 
{ 

public function login() 
{ 
    $data = []; 
    require $_SERVER['DOCUMENT_ROOT'].'/socialnetwork-api/Config/db.php'; 
    $DB = new DB();$db=$DB->connection; 
    $username =htmlentities($_POST['username'],ENT_QUOTES,"UTF-8"); 
    $password =htmlentities($_POST['password'],ENT_QUOTES,"UTF-8"); 
    $sql = "SELECT * FROM `tbl_users` WHERE `username`='$username' AND `password`='$password'"; 
    $result = $db->query($sql); 
    $result = $result->fetch(); 
    if($result != null) 
    { 
     $data["result"]=$result['id']; 
    } 
    else 
    { 
     $data["result"]="0"; 
    } 
    echo json_encode($data); 
} 

public function signup() 
{ 
    $data = []; 
    require $_SERVER['DOCUMENT_ROOT'].'/socialnetwork-api/Config/db.php'; 
    $DB = new DB();$db=$DB->connection; 
    $fullname = htmlentities($_POST['full_name'],ENT_QUOTES,"UTF-8"); 
    $username = htmlentities($_POST['username'],ENT_QUOTES,"UTF-8"); 
    $email = $_POST['email']; 
    $password = htmlentities($_POST['password'],ENT_QUOTES,"UTF-8"); 
    $sql = "SELECT * FROM `tbl_users` WHERE `username`='$username'"; 
    $result = $db->query($sql); 
    $result = $result->fetch(); 
    if($result != null) 
    { 
     $data["result"] = "username"; 
    } 
    else 
    { 
     $sql = "SELECT * FROM `tbl_users` WHERE `email`='$email'"; 
     $result = $db->query($sql); 
     $result = $result->fetch(); 
     if($result != null) 
     { 
      $data["result"] = "email"; 
     } 
     else 
     { 
      $sql = "INSERT INTO `tbl_users` (`full_name`,`username`,`email`,`password`) VALUES ('$fullname','$username','$email','$password')"; 
      $result = $db->prepare($sql); 
      $result = $result->execute(); 

      if($result) 
      { 
       $data["result"]="1"; 
      } 
      else 
      { 
       $data["result"]="0"; 
      } 
     } 
    } 
    echo json_encode($data); 
} 

我希望有人可以幫助我，因爲我不熟悉PHP這麼多，我需要爲我的在大學的項目。

Answer 1

未定義的索引錯誤對應於您在班級中使用$_POST。這意味着當你調用這些類函數時，這些值不會被設置。

通常，如果您打算使用$_POST，那麼您的窗體會調用您的PHP腳本，並且每個窗體輸入對應於$_POST的值。

舉例來說，如果你有一個表單的輸入，如：

<input type="text" name="username" value=""> 

然後，當用戶提交表單，你可以得到$_POST['username']值。

但是，如果您沒有表單提交，那麼您將不會有任何$_POST值。因此，未定義的索引錯誤。

另一種方法是將所需的值傳遞給類方法。然後，當您調用方法時，您需要確保您傳遞這些值。

例子：

public function login($username = '', $password = '') 
{ 
    $data = []; 
    require $_SERVER['DOCUMENT_ROOT'].'/socialnetwork-api/Config/db.php'; 
    $DB = new DB();$db=$DB->connection; 
    $username =htmlentities($username,ENT_QUOTES,"UTF-8"); 
    $password =htmlentities($password,ENT_QUOTES,"UTF-8"); 
    $sql = "SELECT * FROM `tbl_users` WHERE `username`='$username' AND `password`='$password'"; 
    $result = $db->query($sql); 
    $result = $result->fetch(); 
    if($result != null) 
    { 
     $data["result"]=$result['id']; 
    } 
    else 
    { 
     $data["result"]="0"; 
    } 
    echo json_encode($data); 
} 

那麼你可以傳遞數據：

$class = new user(); 
$class->login($username, $password); 

這是給你，然後在值傳遞的$username和$password。