Unexpected token < in jquery ajax call for PHP

Question

I am having jquery ajax call as follows.

$("form.form-signin").submit(function (e) {
        e.preventDefault();
        var $form = $(this);
        $.ajax({
            url : "scripts/logincontroller.php",
            type: "POST",
            dataType :"json",
            data: {
                username : $form.find("input[name='username']").val(),
                password : $form.find("input[name='password']").val()
            },
            success: function(response){
                $("div.jumbotron div#error_panel").css("display","block");
                var err_msg = '';
                if(response.errors != null){
                    for(i = 0; i<response.errors.length;i++){
                        err_msg += response.errors[i]+"</br>";
                    }
                    $("div.jumbotron div#error_panel div#message").empty().append(err_msg);
                    return;
                }else{
                    $("div.jumbotron div#error_panel div#message").empty().append("ok");
                }
            },
            error: function(xhr, status, errorThrown){
                alert(errorThrown+status);
              $("div.jumbotron div#error_panel").css("display","block");
            }
        });

    });

Now I have following classes. This class connects to database and returns db object if success, string error otherwise.

//DBConfiguration.class.php
namespace db;
class DBC{
    const username = "root";
    const password = "****";
    const host = "localhost";
    const schema = "mydb";

    static function connect(){
        try{
            $dbh = new \PDO('mysql:host='.self::host.';dbname='.self::schema, self::username, self::password, array(
                \PDO::ATTR_PERSISTENT => true
            ));
            $dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
            return $dbh;
        }catch (\PDOException $e){
            return "Failed to connect to database";
        }

    }
}

This class calls the above connect and returns the result.

//Authenticator.php
namespace db;
include "DBConfiguration.class.php";

class Authenticator{
    public function isValidUser($username,$password){
        $result = array();
        $dbh = DBC::connect();
        if(is_string($dbh) && $dbh === "Failed to connect to database"){
            $err = array();
            $err[] =  "Oops! Something went wrong. We are working on it";
            $result["errors"] = $err;
        }else{
            $err = array();
            $err[] =  "connected successfully";
            $result["errors"] = $err;
        }
        return $result;

    }
}

//LOGINCONTROLLER.PHP
header("Content-Type: application/json", true);
include "db\Authenticator.php";
$authenticator = new \db\Authenticator();
echo json_encode($authenticator ->isValidUser($_POST["username"],$_POST["password"]));

When I am intentionally changing the password and could not connect to db I am getting correct error message. But when it is successful (in which case I am returning db object from connect() method), I am getting 'unexpected token <'.

Weird thing is I am able to run the code when I place all these classes in logincontroller.php instead of induvidual namespaces.

Is there any problem with this code?

Answer 1

I found the answer. The following line is causing the problem.

$dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

The above line of code must be

$dbh->setAttribute(\PDO::ATTR_ERRMODE, \PDO::ERRMODE_EXCEPTION);

As I am calling this from a namespaced class PDO must refer to global PDO class.