Empty response by JQuery.ajax and object and php - php

Question

I am stuck by creating my first universal code for ajax responses. I simply do not get an output here, neither in php nor in the ajax response. This must have something to be in the post data.
This is my ajax request:
var info = {};
//get id info
info["ses-id"] = $("#theme").attr("scene");
//get template info
info["ses-template"] = $("#theme").attr("template");
$.ajax({
dataType: "json",
contentType: "application/json; charset=UTF-8",
data: JSON.stringify(info),
type: "POST",
url: "query.php"
}).done(function(data, textStatus, jqXHR) {
alert (data);
//window.location = "?szenen";
console.log("Data sent.");
}).fail(function(jqXHR, textStatus, errorThrown) {
console.log("There was an error." + errorThrown);
});
This is my query.php so far:
<?php
$return = $_POST;
$return["json"] = json_encode($return);
print(json_encode($return));
The output is an object where only the json entry is filled with [].
The stringified variable looks good, it's a string like this:
{"ses-id":"1","ses-template":"2"}
Thanks for any advice!

Answer 1

Your problem is you are sending a json encoded string as the POST body, and then using $_POST to access it. $_POST is an array of key/value POST data. Since your data doesn't have a key, you can't access it from the $_POST array. It's just a value (a string value at that).
If you change your PHP script to be:
<?php
echo file_get_contents("php://input");
?>
It will output the JSON you passed in. Note that there is no need to do a json_encode() because the value is a string, not an array. The json you passed it was never decoded.
Alternatively, if your javascript was:
$.ajax({
data: { "data": JSON.stringify(info) },
type: "POST",
url: "query.php"
})
then your post body would be:
data={"ses-id":"1","ses-template":"2"}
you could then do
<?php
echo $_POST["data"];
?>
Again noting the data you sent it was never decoded, so it's still just a string. PHP does not json_decode for you.

Answer 2

The dataType and contentType both must be deactivated, then I got responses.
$.ajax({
//dataType: "json",
//contentType: "application/json; charset=UTF-8",
data: JSON.stringify(info),
type: "POST",
url: "query.php"
Varying the info object results in varies of the php var but that wasn't my problem.
BIG thanks to everyone especially CJ_Wurtz who pushed me the right way.

Answer 3

It works when you drop contentType and JSON.stringify:
var info = {};
//get id info
info["ses-id"] = $("#theme").attr("scene");
//get template info
info["ses-template"] = $("#theme").attr("template");
$.ajax({
dataType: "json",
data: info,
type: "POST",
url: "query.php"
}).done(function(data, textStatus, jqXHR) {
console.log(data);
//window.location = "?szenen";
console.log("Data sent.");
}).fail(function(jqXHR, textStatus, errorThrown) {
console.log("There was an error." + errorThrown);
});