内部服务器错误 POST 500 AJAX、jQuery + PHP

Question

我整天都在尝试调试，但我无法让内部错误消失。

此代码的功能是它会从表单中获取一封电子邮件并通过数据库运行它以检查数据库中是否已经有一封电子邮件。

如果有，则会显示错误信息 vendor.js:9566 POST http://snacktally.com/emailcheck.php 500 (Internal Server Error)。

这是 jQuery：

$("#userform").submit(function(event) {
  var emailtext = {
    email: $("#Email").val();
  };
  $.ajax({
    type: "POST",
    url: "emailcheck.php",
    data: emailtext,
    dataType: 'json',
    success: function(response, textStatus, req) {
      if (response == '1') {
        //default action
      } else {
        $("#emailField").css("border-left", "2px solid #ff3333");
        $("#passField").css("border-left", "2px solid #FCFCFC");
        $("#passVerField").css("border-left", "2px solid #FCFCFC");
        $("h1").text("Email Taken").css("color", "#ff3333");
        event.preventDefault();
      }
    },
    error: function(xhr, ajaxOptions, thrownError) {
      console.log(xhr.status);
      console.log(xhr.responseText);
      console.log(thrownError);
    }
  });
});

这里是 PHP

<?php
#sql_host, user pass and db defined up here
$con = mysqli_connect($sql_host,$sql_user,$sql_pass,$sql_db);

#obtains the email from the php file
if(isset($_POST('email')))
{
    $email = $_POST('email');

    #runs it through the database
    $emailver = "SELECT `Email` FROM `SnackTally`.`User` WHERE `Email` = 
    '$email'";

    if($select = mysqli_query($con, $emailver)){
        #output 0 = false, not a valid email
        if(mysqli_fetch_assoc($select) > 0)
        {
            #$emailErr = "Email already exists";
            mysqli_free_result($select);
            mysqli_close($con);
            echo '0';
        }
        else
        {
            mysqli_free_result($select);
            mysqli_close($con);
            echo '1';
        }
    }
}else{
    mysqli_close($con);
    echo '0';
}
?>

Answer 1

将$_POST('email') 更改为$_POST['email']

阅读this 以调试您的代码

Answer 2

将 $_POST('email') 替换为 $_POST['email']