我正在尝试通过使用jqueryValidation引擎插件来验证注册表单，某些验证无法正常工作

Question

First of all I have to tell that I am new to php. I am trying to validate a signup form by using jqueryValidation engine plugin. I succeed on validating some parts and now I am stuck at the user name validation part (check whether the name user entered is already in the database and if it is, display 'username is already taken'). When i enter a username 'validating please wait' prompt is displaying and I can't submit the form. I have used bootstrap 3.3.6.

Here is my signup form

<div class="modal fade" id="signupForm" data-backdrop="false" role="dialog">
    <div class="modal-dialog">
        <div class="modal-content Popmodal">
            <div class="modal-header">
                <button type="button" class="close Popclose" data-dismiss="modal" aria-label="">
                    <span>&times;</span>
                </button>
                <h4 class="modal-title Poptit">Sign Up</h4>
            </div>

            <div class="modal-body Popbody">
                <div id="error">
                    <!-- error will be showen here ! -->
                </div>
                <form class="form-horizontal" method="post" action="registration.php" id="reg-form">
                    <div class="form-group"><br>
                        <label class="col-md-4 col-md-offset-1">User Name :</label>
                        <div class="col-md-5">
                            <input type="text" placeholder="A name that you like to use" value = "" class="form-control input-sm popname validate[required,custom[onlyLetterNumber],maxSize[20],ajax[ajaxUserCallPhp]]" name="uname" id="uname" data-errormessage-value-missing="Username is required !" data-prompt-position="bottomLeft:5,4"><br>

                        </div>
                    </div>

                    <div class="form-group">
                        <label class="col-md-4 col-md-offset-1">Email :</label>
                        <div class="col-md-5">
                            <input type="email" placeholder="Your email address" class="form-control input-sm popname validate[required,custom[email]]" name="mail" id="mail" data-errormessage-value-missing="Email is required !"  data-errormessage-custom-error="Invalid email address !" data-prompt-position="bottomLeft:5,4"><br>
                        </div>

                    </div>

                    <div class="form-group">
                        <label class="col-md-4 col-md-offset-1">Password :</label>
                        <div class="col-md-5">
                            <input type="password" maxlength="15" placeholder="Password" class="form-control input-sm popname validate[required]" name="pass" id="pass" data-errormessage-value-missing="Password is required !"  data-prompt-position="bottomLeft:5,4"><br>
                        </div>
                    </div>

                    <div class="form-group">
                        <label class="col-md-4 col-md-offset-1">Confirm Password :</label>
                        <div class="col-md-5">
                            <input type="password" maxlength="15" placeholder="Confirm password" class="form-control input-sm popname validate[required,equals[pass]]" name="cpass" id="cpass" data-errormessage-value-missing="Confirm password is required !" data-errormessage-pattern-mismatch="Password fields do not match !" data-prompt-position="bottomLeft:5,4"><br>
                        </div>
                    </div>

                    <div class="form-group">
                        <div class="col-md-2 col-md-offset-8">
                            <button type="submit" class="btn btn-success sign" value="submit" name="signup">Sign Up</button>
                        </div>
                    </div>
                 </form>
            </div>
        </div>
    </div>
</div>  

Here is the js part

  <script>
    $(document).ready(function(){
    $("#reg-form").validationEngine();
  });
  </script> //this part is on the index page with signup form

"ajaxUserCallPhp": {
                "url": "ajaxValidateFieldUser.php",
                "extraDataDynamic": ['#uname'],
                "alertTextOk": "* This username is available",
                "alertText": "* This user is already taken",
                "alertTextLoad": "* Validating, please wait"
            }

Here is the php code

<?php

  $validateValue=$_REQUEST['fieldValue']; 
  $validateId=$_REQUEST['uname'];


  $validateError= "This username is already taken";
  $validateSuccess= "This username is available";

   $arrayToJs = array();
   $arrayToJs[0] = $validateId;

   require_once('dbconfig.php');

   $stmt = $db_con->query('SELECT uname FROM users WHERE uname    ='$validateValue'');
   $stmt->bindValue(':uname', $uname, PDO::PARAM_STR);
   $stmt->execute();
   $res = $stmt->fetchAll(PDO::FETCH_ASSOC);

   if ($res->fetchColumn() > 0) { 
   $arrayToJs[1] = false;
   echo json_encode($arrayToJs); // RETURN ARRAY WITH ERROR

   } else{

    $arrayToJs[1] = true;
    echo json_encode($arrayToJs); // RETURN ARRAY WITH success
   }

  ?>

Answer 1

Let's start here:

$stmt = $db_con->query('SELECT uname FROM users WHERE uname    = '$validateValue'');
$stmt->bindValue(':uname', $uname, PDO::PARAM_STR);
$stmt->execute();
$res = $stmt->fetchAll(PDO::FETCH_ASSOC);

Your quotes are completely broken, so the file won't even parse. Even with that fixed, there are still many problems.

Here is some documentation on how to do a basic query. In short, prepare then execute. Binding is generally un-necessary for simple SELECT queries, and calling PDO::query() doesn't do anything at all with prepared statements. Try this instead:

$stmt = $db_con->prepare('SELECT uname FROM users WHERE uname = :uname');
$stmt->execute(["uname"=>$validateValue]);

Then PDOStatement::fetchAll() returns an array, but you are trying to call PDOStatement::fetchColumn() on it. Pick one or the other.

There are further problems, but you should take a look at your code line by line and understand what each line does. You can't hope to copy and paste things from a half dozen websites and have it work.