Pass JSON formatted data from PHP script to AJAX

Question

I have a created a PHP class that retrieves all the data from a database and gets back the results in JSON format:

public function getCategories() {
    if (!$this->isConnectionAlive()) {
        $this->getConnection();
    }

    $data = $this->dbconn->prepare("SELECT DISTINCT cat FROM regalo");
    $data->execute();
    $results=$data->fetchAll(PDO::FETCH_ASSOC);
    $json_data = json_encode($results);
}

then an object of the class calls this method and is able to successfully do exactly that:

$dbh = new DatabaseHandler('localhost', 'fakeuser', 'fakepass', 'fakedb');

$dbh->getCategories();

How do I pass this data to my AJAX script so that it can manipulate the JSON-formatted results?

Your getCategories method should return $json_data and you should echo the call to that method at an URL your AJAX script can access — Gargron
– Gargron, Commented Feb 17, 2013 at 19:17

Ethan · Accepted Answer · 2013-06-28 17:54:36Z

3

This should do it in your javascript:

$.get('/getCategories',null,function(response){
  console.log(response);
},"JSON");

And you need to be echo-ing your json encoded data in the php script

public function getCategories() {
    if (!$this->isConnectionAlive()) {
        $this->getConnection();
    }

    $data = $this->dbconn->prepare("SELECT DISTINCT cat FROM regalo");
    $data->execute();
    $results=$data->fetchAll(PDO::FETCH_ASSOC);
    $json_data = json_encode($results);
    header('Content-type: text/json');
    header('Content-type: application/json');
    echo $json_data;
}

I would actually throw that into it's own thing for re-use later on too:

public static function send_json_data($php_array)
{
        header('Content-type: text/json');
        header('Content-type: application/json');
        echo json_encode($php_array);
        exit(); //if you have hooks or something else that executes after output in your script, take this line out.
}

edited Jun 28, 2013 at 17:54

answered Feb 17, 2013 at 19:17

Ethan

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3 Comments

Jay Gilford Over a year ago

You should terminate the script after the echo to prevent any code, wanted or not, from being output (such as errors/warnings/notices)

Ethan Over a year ago

In a production environment errors should be turned off, but I added an exit() either way.

Jay Gilford Over a year ago

Agreed, though in practice a site should have a dev and production environment and your code should work on both in my opinion. +1 for the separate json function. You could take it one step further and check for headers_sent() before output

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