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get_category_by_path() WP 2.1.0

Retrieve category based on URL containing the category slug.

Breaks the $category_path parameter up to get the category slug.

Tries to find the child path and will return it. If it doesn't find a match, then it will return the first category matching slug, if $full_match, is set to false. If it does not, then it will return null.

It is also possible that it will return a WP_Error object on failure. Check for it when using this function.

No Hooks.

Return

WP_Term/Array/WP_Error/null. Type is based on $output value.

Usage

get_category_by_path( $category_path, $full_match, $output );
$category_path(string) (required)
URL containing category slugs.
$full_match(true/false)
Whether full path should be matched.
Default: true
$output(string)
The required return type. One of OBJECT, ARRAY_A, or ARRAY_N, which correspond to a WP_Term object, an associative array, or a numeric array, respectively.
Default: OBJECT

Code of get category by path: wp-includes/category.php WP 5.2.2

<?php
function get_category_by_path( $category_path, $full_match = true, $output = OBJECT ) {
	$category_path  = rawurlencode( urldecode( $category_path ) );
	$category_path  = str_replace( '%2F', '/', $category_path );
	$category_path  = str_replace( '%20', ' ', $category_path );
	$category_paths = '/' . trim( $category_path, '/' );
	$leaf_path      = sanitize_title( basename( $category_paths ) );
	$category_paths = explode( '/', $category_paths );
	$full_path      = '';
	foreach ( (array) $category_paths as $pathdir ) {
		$full_path .= ( $pathdir != '' ? '/' : '' ) . sanitize_title( $pathdir );
	}
	$categories = get_terms(
		'category',
		array(
			'get'  => 'all',
			'slug' => $leaf_path,
		)
	);

	if ( empty( $categories ) ) {
		return;
	}

	foreach ( $categories as $category ) {
		$path        = '/' . $leaf_path;
		$curcategory = $category;
		while ( ( $curcategory->parent != 0 ) && ( $curcategory->parent != $curcategory->term_id ) ) {
			$curcategory = get_term( $curcategory->parent, 'category' );
			if ( is_wp_error( $curcategory ) ) {
				return $curcategory;
			}
			$path = '/' . $curcategory->slug . $path;
		}

		if ( $path == $full_path ) {
			$category = get_term( $category->term_id, 'category', $output );
			_make_cat_compat( $category );
			return $category;
		}
	}

	// If full matching is not required, return the first cat that matches the leaf.
	if ( ! $full_match ) {
		$category = get_term( reset( $categories )->term_id, 'category', $output );
		_make_cat_compat( $category );
		return $category;
	}
}