How to create in php a search.json twitter-like

Question

Hi,

I've made on my website a search.php file that produce a JSON string, helping me to use real-time ajax for my apps.

But now, I'd like to open it as an API to others, but I discovered that $.get $.getJSON $.ajax doesn't allow to use my search.php file from other servers/domains.

How can I do to transform my php search into a search.json, exactly like Twitter, passing parameters to it.

Thx

Answer 1

Twitter uses two mechanisms to allow cross-domain access to the search.twitter.com domain: crossdomain.xml (for Flash) and JSONP (for JavaScript).

With JSONP, the calling JavaScript includes a callback=? parameter in the URL, where ? is the name of a callback function. The server-side script wraps the encoded JSON as:

?(<JSON here>)

This allows the query parameters to be encoded as the src URL of a script tag, allowing cross-domain access that XMLHttpRequest does not allow. When the data arrives, it is executed as a script. The JavaScript interpreter decodes the JSON since it is a valid subset of JavaScript and then calls the callback function with the decoded JSON as an argument. It shouldn't take more than a few lines of code to implement JSONP in your PHP script.

Answer 2

getJSON is limited by your browser's security restrictions that lock down non-origin domains. In order to do cross-domain, you have to use JSONP, which requires you wrap the data in a function that is defined by the callback variable (e.g. $_GET['jsonp_callback']). e.g.

Search.php

<?php
    echo $_GET['jsonp_callback'] . '(' . json_encode($data). ');'
    // prints: jsonp123({"search" : "value", etc. });
?>

jQuery

$.ajax({
  dataType: 'jsonp',
  data: 'search=value',
  jsonp: 'jsonp_callback',
  url: 'http://yourserver.com/search.php',
  success: function () {
    // do stuff
  },
});

Just make sure that the callback variable that you define in your php script matches the jsonp value that you call through the .ajax query (or it defaults to "callback").