Making all PHP file output pass through a "filter file" before being displayed

Question

Is there any way for all my PHP and/or HTML file output to be "filtered" before being displayed in the browser? I figured that I could pass it through a global function before it is displayed but I'm stuck on the implementation. Please help.

If there is a better way to achieve the same result, I'd be happy to know.

Thanks.

score 15 · Accepted Answer · edited Nov 13 '11 at 15:57

15

Check out ob_start which lets you pass a callback handler for post-processing your script output.

For example, PHP includes a built-in callback ob_gzhandler for use in compressing the output:

<?php

ob_start("ob_gzhandler");

?>
<html>
<body>
<p>This should be a compressed page.</p>
</html>
<body>

Here's a fuller example illustrating how you might tidy your HTML with the tidy extension:

function tidyhtml($input)
{
    $config = array(
           'indent'         => true,
           'output-xhtml'   => true,
           'wrap'           => 200);

    $tidy = new tidy;
    $tidy->parseString($input, $config, 'utf8');
    $tidy->cleanRepair();

    // Output
    return $tidy;
}

ob_start("tidyhtml");

//now output your ugly HTML

If you wanted to ensure all your PHP scripts used the same filter without including it directly, check out the auto_prepend_file configuration directive.

edited Nov 13 '11 at 15:57

random

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answered Jul 22 '09 at 10:40

Paul Dixon

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+1 for good answer, i didn't know the tidy class. Is it a native class ? – Clement Herreman Jul 22 '09 at 10:55
No, it's an extension. Install via PECL, but often packaged for easy install though, e.g. apt-get install php5-tidy on a typical Debian/Ubuntu box. – Paul Dixon Jul 22 '09 at 10:58
Thanks a lot Paul. Excellent answer. Exactly what I was looking for. The auto_prepend_file suggestion was a life-saver. – Gaurav Sharma Jul 23 '09 at 05:35

score 4 · Answer 2 · answered Jul 22 '09 at 10:41

4

You can use output buffering and specify a callback when you call ob_start()

<?php
function filterOutput($str) {
    return strtoupper($str);
}

ob_start('filterOutput');
?>

<html>
    some stuff
    <?php echo 'hello'; ?>
</html>

answered Jul 22 '09 at 10:41

Tom Haigh

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score 2 · Answer 3 · answered Jul 22 '09 at 10:41

You can use PHP's output buffering functions to do that

You can provide a callback method that is called when the buffer is flushed, like:

<?php

function callback($buffer) {   
    // replace all the apples with oranges  
    return (str_replace("apples", "oranges", $buffer)); 
}

ob_start("callback");
?>
<html>
<body>
    <p>It's like comparing apples to oranges.</p>
</body>
</html>

<?php
ob_end_flush();
?>

In that case output is buffered instead of sent from the script and just before the flush your callback method is called.

score 0 · Answer 4 · answered Jul 22 '09 at 10:38

0

Have a look at using Smarty. It's a templating system for PHP, that is good practice to use, and into which you can plug global output filters.

answered Jul 22 '09 at 10:38

Tim Ebenezer

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score 0 · Answer 5 · answered Jul 22 '09 at 10:41

edit: Paul's reply is better. So it would be

ob_start("my_filter_function");

My original reply was:

That can be achieved with output buffering.

For example:

ob_start();
// Generate all output
echo "all my output comes here."
// Done, filtering now
$contents = ob_get_contents();
ob_end_clean();
echo my_filter_function($contents);

Making all PHP file output pass through a "filter file" before being displayed

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