Send html answer from PHP to Ajax - php

Question

Here is what I'm trying to do:
I use an Ajax call to select messages from my database, I echo the content in my PHP and i try to get the echoed html in the Ajax success. But it does not work. Here is the code.
JQUERY:
function SelectMessages()
{
console.log("Selecting messages");
console.log("Talk = " + talk);
$.ajax({
url: "select_messages.php",
type: "GET",
data: "talk=" + talk,
success: function (html) {
alert(html);
console.log("In success");
$("#message_box").prepend(html)
},
error: function (html) {
alert(html);
console.log("In error");
}
});//ajax()
}//SelectMessages()
PHP:
<?php
//SELECTING MESSAGES
require 'dbconnect.php';
header('Cache-Control: no-cache, must-revalidate');
header('Expires: Mon, 26 Jul 1997 05:00:00 GMT');
header('Content-type: application/json');
if ($_GET['talk'] != "") {
$request = $bdd->prepare('SELECT AUTHOR,CONTENT FROM MESSAGE WHERE TALK = :talk');
$request->execute(array("talk"=>$_GET['talk']));
while ($data = $request->fetch(PDO::FETCH_ASSOC)) {
echo' <p> '.$data['CONTENT'].'</p>';
}
}
?>
Using this code, I get "In error" displayed on the console and the code in the alert is "[object Object]". However, the status of my query is "OK" in my browser and the echoed result in the network window is the one expected with all the right values of messages.
I just don't understand why I get through the error instead of success.
Please do not mark this as a duplicate as I have already checked and tested the Ajax/PHP solutions and did not get any result.

Answer 1

In your php file you have set content type header as follows
header('Content-type: application/json');
but normally echoed the response as plain text/html. Either you have to send the response in json.
echo json_encode($data['CONTENT']);
Or remove content-type header as json.