README

Small library for SEO-related functionality in WordPress themes and plugins.

What problem does it solve?

Themes and plugins often know the best title, description and share image for a page, but they can't know whether the site runs an SEO plugin. Printing your own <meta> tags then leads to duplicates; printing none leaves sites without an SEO plugin with empty tags.

This library handles both cases. You provide the values through filters, and the library decides where they go:

No SEO plugin active: it sets the <title> and prints og:title, meta description, og:description and og:image.
SEO plugin active: it prints nothing. Instead it hands your values to the plugin where it has none, and keeps values an editor has set in the plugin. See SEO plugin support.

It also has a helper that removes tags WordPress puts in the <head> by default but that most sites don't need.

Requirements

PHP 8.1+
WordPress

Installation

composer require lloc/seo

Usage

use lloc\SEO\Meta\Description;
use lloc\SEO\Meta\Image;
use lloc\SEO\Meta\Title;
use lloc\SEO\Utils\CleanUp;

( new Title() )->register();
( new Description() )->register();
( new Image() )->register();

CleanUp::head();

Then provide the values through filters. Each filter receives the ID of the queried object (get_queried_object_id()). An empty return value means "nothing to add", and no tag is printed.

Title

Filter: lloc_seo_meta_title

add_filter( 'lloc_seo_meta_title', function ( string $title, int $object_id ): string {
	return get_post_meta( $object_id, 'my_seo_title', true ) ?: $title;
}, 10, 2 );

Without an SEO plugin, the value replaces the document title (pre_get_document_title, needs add_theme_support( 'title-tag' )) and is printed as <meta property="og:title"> in wp_head.

Description

Filter: lloc_seo_meta_description

add_filter( 'lloc_seo_meta_description', function ( string $description, int $object_id ): string {
	return is_singular() ? wp_strip_all_tags( get_the_excerpt( $object_id ) ) : $description;
}, 10, 2 );

Without an SEO plugin, it prints <meta name="description"> and <meta property="og:description"> in wp_head.

Share image

Filter: lloc_seo_meta_image

The filter receives and returns an array with the keys url, width, height and type. Missing keys are filled with defaults; an empty url means no image.

add_filter( 'lloc_seo_meta_image', function ( array $image, int $object_id ): array {
	$attachment_id = get_post_thumbnail_id( $object_id );
	$src           = $attachment_id ? wp_get_attachment_image_src( $attachment_id, 'large' ) : false;
	if ( ! $src ) {
		return $image;
	}

	return array(
		'url'    => $src[0],
		'width'  => $src[1],
		'height' => $src[2],
		'type'   => get_post_mime_type( $attachment_id ),
	);
}, 10, 2 );

Without an SEO plugin, it prints og:image in wp_head, plus og:image:width and og:image:height when they are greater than 0.

SEO plugin support

With an SEO plugin active, the library prints nothing and passes your values to the plugin's own filters instead. A value the plugin already has (set by an editor or generated from the plugin's templates) is kept, so your value only fills gaps.

Plugin	Title	Description	Image
Yoast SEO	title, `og:title`	description, `og:description`, `twitter:description`	`og:image`
Rank Math	title, `og:title`, `twitter:title`	description, `og:description`, `twitter:description`	`og:image`, `twitter:image`
All in One SEO	title	description	–
SEOPress	title	description	–
The SEO Framework	title, `og:title`, `twitter:title`	description, `og:description`, `twitter:description`	–

The hooks are listed in the SEO_PLUGIN_FILTER constants of Title, Description and Image, except for The SEO Framework, which is registered separately in register(). For The SEO Framework the library uses its custom-field filters, so your value replaces the generated one; its social tags fall back to it unless they are set separately.

Clean up the head

CleanUp::head() removes:

the RSD link (points to xmlrpc.php),
the Windows Live Writer manifest link,
the WordPress version (generator tag and feeds),
the emoji detection script and styles.

Check for SEO plugins

Use the helper in your own code to check whether an SEO plugin is active:

use lloc\SEO\Helper\Plugins;

if ( ! Plugins::active() ) {
	// Print your own tags.
}

Development

composer install
composer qa          # phpcs, phpstan and phpunit
composer phpcs:fix   # fix coding standard violations

License

GPL-2.0-or-later

lloc / seo

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