AJAX call fails when sending JSON but works with URL style string

Question

When making an AJAX request is works when my data is a URL style string.

var options = {
    type: 'post',
    data: 'action=my_action'
};

The function will get called and return some fake data just fine.

If I try to make the same call but use JSON, it doesn't work. I've tried several different ways of doing it, but admin.php just return -1.

Is there something in jQuery or Wordpress that I need to change to allow this?

Here are a couple of the other ways I've tried.

var options = {
    type: 'post',
    data: { action: 'my_action' }
};

var options = {
    type: 'post',
    data: JSON.stringify({ action: 'my_action' })
};

The example in the docs have it using a JSON object too. http://codex.wordpress.org/AJAX_in_Plugins

Answer 1

Firstly, stringify won't build a URL query - it serializes it into JSON object notation.

And secondly, you don't even need to build the URL query - if you're using jQuery to make the AJAX call, just pass the JSON object as it is - jQuery.param() will internally handle it :)

Answer 2

Ignore this reply if you're not copying the bad practice examples provided in the wordpress codex.

If you are, I'd recommend reading this article on properly (and securely) using Ajax in WP: http://www.garyc40.com/2010/03/5-tips-for-using-ajax-in-wordpress/

That article is actually also linked on the codex page, so I'm left wondering why the examples on the codex page are still written as they are.