How to send a json string back to jquery - php

Question

I need to send some data to an external php page and that page has to send the required data back to jQuery. My question is how can I send the data from the external page back to jQuery on the page that send it.
This is the jQuery code that sends the data to the external page:
function LoadImageData(url)
{
$.ajax({
url: 'get_image_data.php',
dataType: 'json',
data: {'url': url },
success: SetTag()
});
}
This is the PHP code htat receives the data and is required to send some data back:
<?php
require_once('FaceRestClient.php');
$apiKey = '**********************';
$apiSecret = '**********************';
$api = new FaceRestClient($apiKey, $apiSecret);
$active_url = $_POST['url'];
$photos = $api->faces_detect($active_url);
return $photos;
?>
So my problem is, how can I send the data backto jQuery. Just a simple return does not seem to work.
Thanks in Advance,
Mark

Answer 1

You need to echo the resulting JSON:
echo $photos;
If $photos is not already JSON, use json_encode:
echo json_encode( $photos);

Answer 2

One would think the REST API would give you JSON, but you need to check if it's valid JSON (JSONP is not valid here) ?
You could just drop the dataType in your Ajax function and let jQuery figure it out, that way atleast you'll get something back if it's not valid JSON.
Try this:
$.ajax({
url: 'get_image_data.php',
type: 'POST',
data: {'url': url }
}).done(function(data) {
console.log(data);
}).fail(function() {
console.log('Your ajax just failed');
});
Open the console, and see what is printed
At the end of a PHP function I tend to do :
exit(json_encode($someData));
To return the data as JSON, but anything that prints the data is ok.

Answer 3

try this
echo json_encode( $photos);

Answer 4

you need to echo
echo $photos;
and as metntoned by #nickb if $photo is not already a json then convert it into json first and then echo.
echo json_encode($photos)
in jQuery if you want to fetch the data
onSuccess: function(data, status) {
//var data contains the returned json.
}