How to get response from PHP using AJAX

Question

The idea in this code is to print the amount of followers that an user has...

This is the code I've created

AJAX

$(document).ready(function() {
var usuario = $(".left h4").attr("data-id");
var seguidor = $("#user_account_info .profile_ball").attr("data-id");

$.ajax({
    type: "POST",
    url: "./include/php/followers.php",
    data: { user: usuario, follower: seguidor },
    success: function(data) { $(".right h4 i").html(data); }
});
return false;
});

PHP

<?php
$dsn = "mysql:host=localhost;dbname=tapehd;charset=utf8";
$usuario = "root";
$contraseña = "";

$conexion = new PDO($dsn, $usuario, $contraseña);
$resultado = null;

$user = $_POST["user"];
$seguidor = $_POST["follower"];

$sql = "SELECT count(*) as seguidores FROM seguidores WHERE id_canal = '$user'";

if(isset($resultado)){ $datos = $resultado->fetch(); }

$seguidores = $datos["seguidores"];

return $seguidores;
?>

I'm returning the result in the php file and taking back the data in the php one. I print in the div I want to display, but it shows me only an error:

Notice: Undefined variable: datos in C:\wamp\www\tapeHD\include\php\followers.php on line 16

You're not checking your queries for errors and just assume that they work. You need to add some error checking to your queries. — Jay Blanchard, Sep 01 '15 at 20:16
[Your script is at risk for SQL Injection Attacks.](http://stackoverflow.com/questions/60174/how-can-i-prevent-sql-injection-in-php) — Jay Blanchard, Sep 01 '15 at 20:17
You never execute your query. You have multiple problems, not dissimilar to a question you asked earlier today. If you will follow some of the advice that folks have given you it would reduce the number of problems you're experiencing. — Jay Blanchard, Sep 01 '15 at 20:19
Your `$resultado` is NULL so the fetch in the if-statement never gets executed, therefore `$datos` is undefined. — Victor Levin, Sep 01 '15 at 20:19
note - `return $seguidores;` needs to be `echo $seguidores;` as `return` does not print out the value — Sean, Sep 01 '15 at 20:21

score 1 · Accepted Answer · answered Sep 01 '15 at 20:18

1

Looks like the problem is $datos is only set if $resultado is set. And nowehere in your script is the SQL query actually being executed. I would set a default value for $datos and execute your query.

answered Sep 01 '15 at 20:18

SamA

587
3
6

1

omg... thanks dude... such stupid fail. Sorry for being annoying – Antonio Sep 01 '15 at 20:33

score 0 · Answer 2 · answered Sep 01 '15 at 20:20

It looks like it could be because $resultado is null and therefore not set. So when the condition statement of if(isset($resultado)..... comes up, it's actually not executing and causing $datos to populate. Therefore $datos["seguidores"]; doesn't exist when you try to assign it to $seguidores.

How to get response from PHP using AJAX

2 Answers2