wp_get_canonical_url( int|WP_Post $post = null ): string|false
- Since
- 4.6.0
- Source
wp-includes/link-template.php:4068
Description
When the post is the same as the current requested page the function will handle the pagination arguments too.
Compatibility
- WordPress
- since 4.6.0
- PHP
- 7.4–8.6-dev
- 6.7.7
- 6.8.8
- 6.9.7
- 7.0.4
- 7.1.0
Present in every tracked release (6.7.7 to 7.1.0), and compiles on PHP 7.4 through 8.6-dev.
Parameters
$postint|WP_Postoptional- Post ID or object. Default is global
$post.Default:null
Return value
string|false- The canonical URL. False if the post does not exist or has not been published yet.
Performance profile
How much work a call to wp_get_canonical_url() does, and what it touches: the algorithmic scaling, the Zend instruction count per call across PHP versions, the hooks it hands control to, and the core code that calls it. Measured from the compiled opcodes, not a stopwatch, so every number is identical on any machine running the same PHP version, and every function in core is ranked by cost.
- Cost class
- Heavy
- Scaling
- Constant
- Instructions
- 7–56
- Plugin surface
- 1 hook
- Called by
- 1
Reaches the database via get_post().
No loop in the body: the same number of instructions runs whatever you pass in.
Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 65.
Third-party callbacks on 'get_canonical_url' run inside this call, and their cost is not bounded by anything here.
1 place in core call this, so the cost is paid more often than your own code shows.
What it touches
- querycontent query
get_post()called directly - optionoption read or write
get_option()called directly - hookthird-party callbacks
apply_filters()called directly - cacheobject cache
wp_cache_get()one call below wp_get_canonical_url() - serializeserialisation
maybe_unserialize()one call below wp_get_canonical_url()
Further down the call graph this can also reach transient. That is the worst case, several calls deep and usually down an error path, not what a normal call pays.
What one call costs · 9 distinct outcomes
One number would be a lie: the work depends on which branch runs. These are every distinct cost wp_get_canonical_url() can have, taken from its control-flow graph on PHP 8.5.
| When | Instructions | Calls it makes |
|---|---|---|
| always | 7 | get_post() |
| always | 12 | get_post(), get_post_status() |
| always | 26 | get_post(), get_post_status(), get_permalink(), get_queried_object_id(), apply_filters() |
!$page | 39 | get_post(), get_post_status(), get_permalink(), get_queried_object_id(), get_query_var(), get_query_var(), apply_filters() |
!$page | 43 | get_post(), get_post_status(), get_permalink(), get_queried_object_id(), get_query_var(), get_query_var(), get_comments_pagenum_link(), apply_filters() |
$page && !get_option() | 50 | get_post(), get_post_status(), get_permalink(), get_queried_object_id(), get_query_var(), get_option(), add_query_arg(), get_query_var(), apply_filters() |
$page && get_option() | 52 | get_post(), get_post_status(), get_permalink(), get_queried_object_id(), get_query_var(), get_option(), trailingslashit(), user_trailingslashit(), get_query_var(), apply_filters() |
$page && !get_option() | 54 | get_post(), get_post_status(), get_permalink(), get_queried_object_id(), get_query_var(), get_option(), add_query_arg(), get_query_var(), get_comments_pagenum_link(), apply_filters() |
$page && get_option() | 56 | get_post(), get_post_status(), get_permalink(), get_queried_object_id(), get_query_var(), get_option(), trailingslashit(), user_trailingslashit(), get_query_var(), get_comments_pagenum_link(), apply_filters() |
Across PHP versions
Compiles the same on PHP 7.4, 8.1, 8.2, 8.3, 8.4, 8.5 and 8.6-dev: 65 instructions, 7–56 executed per call, 6 branches. The work does not change between versions.
An instruction is not a fixed amount of time, so a matching count is not necessarily the same speed; what it rules out is a difference in the work itself.
Hooks and filters fired · 1
One hook fires while wp_get_canonical_url() runs, in this order:
- apply_filters( get_canonical_url )filterline 4106 (+38 into the body)
Filters the canonical URL for a post.
Uses · 11
- get_post()Retrieves post data given a post ID or post object.
- get_post_status()Retrieves the post status based on the post ID.
- get_permalink()Retrieves the full permalink for the current post or post ID.
- get_queried_object_id()Retrieves the ID of the currently queried object.
- get_query_var()Retrieves the value of a query variable in the WP_Query class.
- get_option()Retrieves an option value based on an option name.
- add_query_arg()Retrieves a modified URL query string.
- trailingslashit()Appends a trailing slash.
- user_trailingslashit()Retrieves a trailing-slashed string if the site is set for adding trailing slashes.
- get_comments_pagenum_link()Retrieves the comments page number link.
- apply_filters()Calls the callback functions that have been added to a filter hook.
Used by · 1
- rel_canonical()Outputs rel=canonical for singular queries.
Source code
function wp_get_canonical_url( $post = null ) { $post = get_post( $post ); if ( ! $post ) { return false; } if ( 'publish' !== get_post_status( $post ) ) { return false; } $canonical_url = get_permalink( $post ); // If a canonical is being generated for the current page, make sure it has pagination if needed. if ( get_queried_object_id() === $post->ID ) { $page = get_query_var( 'page', 0 ); if ( $page >= 2 ) { if ( ! get_option( 'permalink_structure' ) ) { $canonical_url = add_query_arg( 'page', $page, $canonical_url ); } else { $canonical_url = trailingslashit( $canonical_url ) . user_trailingslashit( $page, 'single_paged' ); } } $cpage = get_query_var( 'cpage', 0 ); if ( $cpage ) { $canonical_url = get_comments_pagenum_link( $cpage ); } } /** * Filters the canonical URL for a post. * * @since 4.6.0 * * @param string $canonical_url The post's canonical URL. * @param WP_Post $post Post object. */ return apply_filters( 'get_canonical_url', $canonical_url, $post );}Changelog
Introduced in 4.6.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
About this page
- Parsed data
- Generated from the wordpress-develop 7.1.0 tag, from
src/wp-includes/link-template.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it. - Corrections
- Something wrong on this page? Report it and it gets fixed in the next regeneration.