PHP

PHP is a server-side scripting language created in 1995 for web development. The PHP category includes posts about WordPress Plugins and general PHP coding practices / snippets.

Remove WordPress Action / Filter Hooks by Name

JS Morisset PHP, WordPress

The WordPress remove_action() and remove_filter() functions are useful, but they require the original hook priority and a function name, a class object and method name, or a class name and static method name.

Providing the class object in particular may be difficult or impossible, as plugin and theme classes may be extended and instantiated any number of ways. The following SucomUtilWP::remove_filter_hook_name() static method can be used to remove WordPress action and filter hooks using their class name instead of requiring a class object.

For example, if an action hook like this one has been added within a class object that was not saved, saved in a private/protected variable, or cannot be re-instantiated, then removing it might be impossible.

add_action( 'action_name', array( $this, 'method_name' ), 1000, 2 );

If you know the class (or extended class) name (‘Plugin_Namespace\Class_Name’ for this example), you can remove it using the following static method:

SucomUtilWP::remove_filter_hook_name( 'action_name', 'Plugin_Namespace\Class_Name::method_name' );

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Choosing your PHP Image Extension for WordPress

JS Morisset PHP, WordPress

WordPress supports two different PHP image processing extensions — ImageMagick and GD — with a preference for ImageMagick over GD (even when ImageMagick is not installed). The GD extension can still be used in cases where the preferred WordPress ‘WP_Image_Editor_Imagick’ class does not provide support for the requested mime-type or class method.

In some cases, the ImageMagick extension might not be installed, or might be unreliable (old versions of ImageMagick can be buggy). You can hook the WordPress ‘wp_image_editors’ filter to manage the preferred order of WordPress image classes.

For example, here’s a filter and function to remove the ImageMagick class altogether:

add_filter( 'wp_image_editors', 'select_wp_image_editors' );

/**
 * The default $editors value:
 * 
 *      array( 'WP_Image_Editor_Imagick', 'WP_Image_Editor_GD' )
 */
function select_wp_image_editors( $editors ) {

        return array( 'WP_Image_Editor_GD' ); // only return WP_Image_Editor_GD
}

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Fix “sslverify=false” for Pro Plugin / Theme Updates

JS Morisset Community, PHP, WordPress

This is a pet peeve of mine – some plugin and theme authors (to make their lives easier) set “sslverify = false” in their Pro / Premium version update checks and/or other HTTP requests.

Luckily a few security and error checking plugins like the Query Monitor plugin (for example), will show a warning if the WordPress wp_remote_get() function is executed with “sslverify = false”. To make sure this is never the case, you can use the following filters in your functions.php file.

 
add_filter( 'https_ssl_verify', '__return_true', PHP_INT_MAX );

add_filter( 'http_request_args', 'http_request_force_ssl_verify', PHP_INT_MAX );

function http_request_force_ssl_verify( $args ) {

        $args[ 'sslverify' ] = true;

        return $args;
}

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Is your filter going to break the WordPress layout?

JS Morisset PHP, WordPress

If you’re not clear about the difference between WordPress actions and filters, you may end up breaking the page layout of WordPress – maybe days, months, or even years after you’ve written and implemented a new filter hook. The difference can be difficult for new developers to grasp – after all, hooking an action or filter runs your code, either way, right? Well, yes, it does, but filters can be executed several times, in different locations as the webpage is being built (header, body, footer, etc.), and even in the admin back-end. But more importantly, filters do not send anything to the webpage! Filter hooks receive their data / text as an argument, and then “return” the modified (or original) data / text at the end. They do not use “echo”, “print”, “printf”, etc. – they should not send anything to the webpage. If you need to output something directly to the webpage, use an action – that’s what they’re for. ;-)

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PHP – Print a Prettier Array

JS Morisset PHP

I often want to output an array for debugging purposes, but using var_dump() or print_r() on an array that includes true / false values and class objects can be problematic — false values appear empty, and class objects can include too much information. I wrote the following recursive static method (presented here as a function) to pre-filter an array for readability when using print_r() or var_dump().

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Read Adobe XMP / XML in PHP

JS Morisset PHP, WordPress

I’ve found a few snippets of PHP code to read XMP / XML meta data from an image file, but none that I would call very robust or efficient. I ended up writing my own for Underwater Focus, and I’m quite pleased with the result. In fact, after adding support for a shortcode, I packaged it as an Adobe XMP plugin for WordPress.

The first part of using XMP meta data is reading the XMP information from the image. I’ve seen a few solutions that read the whole file into memory, and others that read-in just a small part. If the XMP / XML contains a lot of information, that small part may be incomplete. And each time the XMP meta data is required, the original (and sometimes quite large) image file must be re-read. Since the XMP doesn’t change unless the original image is updated, there’s no reason to keep re-reading the same large file time and time again.

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Adobe XMP with an Hierarchical Subject Array in PHP

JS Morisset PHP

This morning I had a bit of a challenge parsing Adobe XMP information for images on Underwater Focus. The Adobe XMP is too complex for SimpleXML, and anyway, I only needed a few values — one of them, the LightRoom hierarchicalSubject keywords, is the reason I’m sharing some of the code I wrote.

Using regular expressions to get at single values is quick and easy, but I wanted to create arrays for `rdf:li` values, and split each `lr:hierarchicalSubject` keyword into an additional second-dimension array.

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