引用MySQL元素时PHP中未定义的变量

Question

编辑：我解决了这个问题！ 这是一个与我发布的代码无关的问题 - 我在脚本中有一个退出命令 - 但是你的所有建议在其他方面仍有帮助。

当他们在体育网站上填写他们的选秀权时，我正试图自动向用户发送电子邮件。 脚本的早期部分有效：它们的选择在数据库中正确插入或更新。 当我尝试从MySQL数据库中的表中提取用户的电子邮件地址并使用它向其发送消息时，脚本中断。 但是这个错误很奇怪的是它不会导致任何错误消息，并且由于某种原因阻止某些echo语句在允许其他情况下运行。

这是相关的代码：

...

      //set variable for the userID, grabbed from the session array
      $userID = $_SESSION['identifier'];

...

      //write query to get user's e-mail from the database
      $getEmail = "SELECT `email` FROM `useraccounts` WHERE `userID` = '".$userID."'";

      //execute query
      $result = $db->query($getEmail);

      //check if query failed
      try
      {
        if (!$result)
        {
          throw new customexception("Some kind of database problem occurred when trying to find your e-mail address.");
        }
      }
      catch (customexception $e)
      {
        include 'error.html';
        echo $e;
        $db->close();
        include 'footer.php';
        exit;
      }

      //get the info from the row
      $row = $result->fetch_assoc();

      //check if function ran, catch exception if it failed
      try
      {
        if ($row === false)
        {
          throw new customexception("Some kind of database problem occurred when trying to get your e-mail address from your user record in the database.");
        }
      }
      catch (customexception $e)
      {
        include 'error.html';
        echo $e;
        $db->close();
        include 'footer.php';
        exit;
      }

      //set e-mail variable
      $email = $row['email'];

      //set up e-mail information to send a record of their picks to the user
      $toAddress = "$email";

      $subject = "Your Picks";

      $fromAddress = "From: picks@mysite.com";

      //take the info the user submitted, format it for the e-mail, and assign to variable $mailContent
      //the $winner1, $spread1, etc. variables are defined earlier in the function, and were successfully submitted into the database
      $mailContent =  "You picked $winner1 to win by $spread1 points, $winner2 to win by $spread2 points, $winner3 to win by $spread3 points, $winner4 to win by $spread4 points, and $winner5 to win by $spread5 points. \n".
                      "You can change your picks at any time before 1:00pm EST, February 27, 2011. Just go back to the form on the game page and enter your new picks. Good luck!";

      //use wordwrap to limit lines of $mailContent to 70 characters
      $mailContent = wordwrap($mailContent, 70);

      //send the e-mail
      $isMailed = mail($toAddress, $subject, $mailContent, $fromAddress);

      //debug: check if mail failed
      if (!$isMailed)
      {
        echo "Mail failed.";
      }

      //debug: echo $email to see if there's anything in there
      echo "<p>E-mail: $email</p>";

      //debug: echo $toAddress to see if there's anything in there
      echo "<p>To address: $toAddress</p>";

      //if everything succeeded, write reply and close database
      echo $reply;
      $db->close();
    ?>

为了清楚起见，$ userID设置正确，因为他们的选择像他们应该的那样进入数据库。 代码中列出的所有异常都没有出现，这意味着查询似乎已成功运行。 我通过从PHP代码复制并直接在MySQL数据库上运行它来再次检查查询。 当它直接运行时，它为我输入的每个userID值找到了正确的电子邮件地址。

但邮件永远不会被传递，当我尝试回显$ email和$ toAddress变量时，看看它们是否为空：

      //debug: echo $email to see if there's anything in there
      echo "<p>E-mail: $email</p>";

      //debug: echo $toAddress to see if there's anything in there
      echo "<p>To address: $toAddress</p>";

......没有任何表现。 甚至没有错误消息。 这并不一定意味着变量是空的：甚至不回显标签。

我还尝试使用我的个人电子邮件硬编码代码而不是$ toAddress，并且没有发送邮件。 所以邮件功能不起作用。

我还应该注意到，脚本仍然成功地回应了$ reply（这是一个很早就定义的字符串）。

真正奇怪的是，我的网站的登录脚本使用了几乎完全相同的代码并完美运行：

            $getuserID = "SELECT `userID` FROM `useraccounts` WHERE `u_name` = '".$login."' AND `p_word` = SHA1('".$password."')";

            $result = $db->query($getuserID);

            //check if query ran, catch exception if it failed
            try
            {
              if ($result === false)
              {
                throw new customexception("Some kind of database problem occurred when trying to find your user ID.");
              }
            }
            catch (customexception $e)
            {
              include 'error.html';
              echo $e;
              $db->close();
              include 'footer.php';
              exit;
            }

            //get the info from the row
            $row = $result->fetch_assoc();

            //check if function ran, catch exception if it failed
            try
            {
              if ($row === false)
              {
                throw new customexception("Some kind of database problem occurred when trying to get info from your user record in the database.");
              }
            }
            catch (customexception $e)
            {
              include 'error.html';
              echo $e;
              $db->close();
              include 'footer.php';
              exit;
            }

            //set userID variable
            $userID = $row['userID'];

            //assign the session identifier and include successfullogin.html if all is well
            $_SESSION['identifier'] = $userID;

我曾经有一个注册脚本每次有新用户时都给我发电子邮件，所以我知道mail（）通常与我的托管服务提供商一起工作：

        //set up static e-mail information
        $toAddress = "myemail@mysite.com";

        $subject = "Advance Sign-Up";

        $mailContent = "Name: $firstName $lastName \n".
                       "Username: $username \n".
                       "Password: $password \n".
                       "E-mail: $email \n".
                       "Country: $country \n".
                       "State: $state \n".
                       "City: $city \n".
                       "ZIP: $zip \n";

        $fromAddress = "From: $email";

...

        mail($toAddress, $subject, $mailContent, $fromAddress);

这个bug对我来说完全不可思议。 我希望至少可以使用某种错误信息。 任何人都可以看到什么是错的？

Answer 1

它应该是一个注释，但为了格式化。
你的错误处理方式很不寻常。
如果你真的想要使用异常，它应该采用不同的方式：一个尝试阻止和多个抛出：

  try
  {
    $getEmail = "SELECT `email` FROM `useraccounts` WHERE `userID` = '".$userID."'";
    $result = $db->query($getEmail);
    if (!$result)
    {
      throw new customexception("Some kind of database problem occurred when trying to find your e-mail address.");
    }
    $row = $result->fetch_assoc();
    if ($row === false)
    {
      throw new customexception("Some kind of database problem occurred when trying to get your e-mail address from your user record in the database.");
    }
    $email = $row['email'];
    $toAddress = "$email";
    $subject = "Your Picks";
    $fromAddress = "From: picks@mysite.com";
    $mailContent =  "yadda yadda yadda";
    $mailContent = wordwrap($mailContent, 70);

    mail($toAddress, $subject, $mailContent, $fromAddress);

  }
  catch (customexception $e)
  {
    include 'error.html';
    echo $e;
    $db->close();
    include 'footer.php';
    exit;
  }
?>

Answer 2

你肯定数据库变量有内容吗？ 我使用echo（或print）来快速确保变量不为空。 你肯定你的电子邮件代码有效吗？ 尝试使用设定值（例如您自己的个人电子邮件）以确保其有效。

Answer 3

忽略这些通知的最好方法是确保变量存在或在普通PHP中使用isset（），如果！isset（）抛出异常/错误并正确处理它。