Question

I’m writing a PHP application which uses AJAX to submit forms via POST when required. When javascript is not able to be used, I submit the form via HTML/PHP as per normal.

What I really want to do is return JSON or XML to the AJAX call and I don’t want to write all of the form processing logic twice or repeat myself at all really.

I’m trying to determine the best way to write the form processing logic as a single interface which can then be used by both an AJAX call and the PHP script.

I have come up with two options, which both seem like hacks. Hoping I can be given some cleaner/better/more correct solutions or have my two solutions evaluated to determine which one is preferred.

Form: form.php
Processor: process.php

AJAX: JS intercepts submit click in form.php, POSTs to process.php which returns JSON result back to JS. JS updates HTML accordingly using JSON result.

PHP:

Option 1
form.php posts to process.php which outputs HTML if a certain variable is passed with the POST data. e.g.

if ($_POST['output'] == 'html') {
    //output as html
} else {
    //output JSON
}

Option 2
form.php posts to intermediate.php which will then include(‘process.php’), catch the JSON output and use the JSON output to display the HTML as required. e.g.

ob_start();
include('process.php');
$json = json_decode(ob_get_contents());
ob_end_clean();
//use json to create HTML to display to waiting user here

Both of these options seem a little hacky. The second seems cleaner (although I never feel like I’m doing something cleanly when I use ob_start) because it doesn’t require me to write process.php any differently – which emulates an external web service better – although this is not a concern since process.php is fully under my control.

Thoughts?

Thanks as always,
Aaron

Answer 1

I would choose option 1. Just like in popular frameworks like Yii. The typical workflow is like this one:

if (isAjaxRequest()) {
    // Ouput JSON and finish script
    die(json_encode($output));
}
else {
    // This is not AJAX request, proceed
}

And isAjaxRequest is:

// Taken from Yii framework method
function isAjaxRequest() {
    return isset($_SERVER['HTTP_X_REQUESTED_WITH']) && $_SERVER['HTTP_X_REQUESTED_WITH']==='XMLHttpRequest';
}

You don’t need to set certain variable to indicate that the request is via AJAX because browser sends HTTP_X_REQUESTED_WITH header and you just need to check if it’s been set.