Check if user exists with AJAX and PHP

Question

I am trying to create a signup form that checks if the user exists in the database, I inserted a sample user and when I tried signing up with that user it didn't say its already been taken. What have I done wrong?

The JavaScript:

function formSubmit()
    {
    document.getElementById('email_valid').innerHTML = '';

    var temail=document.forms["signup_form"]["temail"].value.replace(/^\s+|\s+$/g, '');


      var atpos=temail.indexOf("@");
        var dotpos=temail.lastIndexOf(".");
        if (atpos<1 || dotpos<atpos+2 || dotpos+2>=temail.length)
          {
          //alert("Not a valid e-mail address");
          setTimeout(function(){document.getElementById('email_valid').innerHTML = '<br/>Email must be valid...';},1000);
          var temailsub=0;
          }
          else
          {
          $.post('/resources/forms/signup/email.php',{email: temail}, function(data){
            document.getElementById('email_valid').innetHTML = data;
            if(data.exists){
                    document.getElementById('email_valid').innetHTML = '<br/>The email address you entered is already in use.';
                    var temailsub=0;
                }else{
                    var temailsub=1;
                }
            }, 'JSON');
          }
    if(temailsub==1e)
      {
        setTimeout(function(){document.getElementById("signup_form").submit();},1000);
      }
      else
      {

        return false;
      }
    }

The PHP file (email.php):

<?php
header('content-type: text/json');
require_once $_SERVER['DOCUMENT_ROOT']."/resources/settings.php";
$query = $pdo->prepare("SELECT * FROM users WHERE email=:email");
$query->execute(array(
    ":email"=> $_POST['email']
));
echo json_encode(array('exists' => $query->rowCount() > 0));
?>

I have checked and double checked the code, I still cannot see why its not detecting that the email has already been used... what do i need to do to fix this and avoid this in the future?

1. Mail addresses don't have to be unique, unless that's your primary key for identifying the user. 2. Are you sure there is no whitespace attached to the mail address you are searching? Case sensitivity considered? Do more debugging by var_dumping stuff you come across and compare with your expectation. — Sven
– Sven, Commented Dec 3, 2012 at 23:26

Mike · Accepted Answer · 2012-12-05 16:33:25Z

2

The problem is that PDOStatement::rowCount() returns the number of rows affected by the last SQL statement. You are performing a SELECT so this value will always be 0. SELECT does not affect any rows. Instead you need to count the number of rows:

$query = $pdo->prepare("SELECT COUNT(*) FROM users WHERE email=:email");
$query->execute(array(
    ":email"=> $_POST['email']
));
$rows = $query->fetchColumn();

echo json_encode(array('exists' => $rows);

Also from jtheman's comment above, you should replace innetHTML with innerHTML in your JavaScript.

edited Dec 5, 2012 at 16:33

answered Dec 3, 2012 at 23:31

Mike

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6 Comments

user115422 Over a year ago

i see where you are going but its still not working... could I have made some other error?

user115422 Over a year ago

WOW, i had a typo in my JavaScript!

Mike Over a year ago

I edited my post to mention your spelling mistake too. Looks like you had two mistakes, not just one.

user115422 Over a year ago

Mike, done, marked as answer :) my IDE didnt pick it up as its a PHP IDE.

user115422 Over a year ago

umm i just tried it again but the code you have given me always returns something... so it always says the email has been used...

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