set_post_thumbnail( int|WP_Post $post, int $thumbnail_id ): int|bool
- Since
- 3.1.0
- Source
wp-includes/post.php:8027
Compatibility
- WordPress
- since 3.1.0
- 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_Post- Post ID or post object where thumbnail should be attached.
$thumbnail_idint- Thumbnail to attach.
Return value
int|bool- Post meta ID if the key didn't exist (ie. this is the first time that a thumbnail has been saved for the post), true on successful update, false on failure or if the value passed is the same as the one that is already in the database.
Performance profile
How much work a call to set_post_thumbnail() 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
- 12–29
- Plugin surface
- None
- Called by
- 7
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 37.
Nothing here hands control to plugin code.
7 places 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 - hookthird-party callbacks
apply_filters()one call below set_post_thumbnail()
Further down the call graph this can also reach serialize, cache, option and transient. Those are the worst case, several calls deep and usually down an error path, not what a normal call pays.
What one call costs · 4 distinct outcomes
One number would be a lie: the work depends on which branch runs. These are every distinct cost set_post_thumbnail() can have, taken from its control-flow graph on PHP 8.5.
| When | Instructions | Calls it makes |
|---|---|---|
| always | 12–13 | get_post(), absint() |
!get_post() | 17 | get_post(), absint(), get_post() |
get_post() && !wp_get_attachment_image() | 28 | get_post(), absint(), get_post(), wp_get_attachment_image(), delete_post_meta() |
get_post() && wp_get_attachment_image() | 29 | get_post(), absint(), get_post(), wp_get_attachment_image(), update_post_meta() |
Across PHP versions
Compiles the same on PHP 7.4, 8.1, 8.2, 8.3, 8.4, 8.5 and 8.6-dev: 37 instructions, 12–29 executed per call, 4 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.
Uses · 5
- get_post()Retrieves post data given a post ID or post object.
- absint()Converts a value to non-negative integer.
- wp_get_attachment_image()Gets an HTML img element representing an image attachment.
- update_post_meta()Updates a post meta field based on the given post ID.
- delete_post_meta()Deletes a post meta field for the given post ID.
Used by · 7
- WP_REST_Posts_Controller::handle_featured_media()Determines the featured media based on a request param.
- wp_ajax_set_attachment_thumbnail()Handles setting the featured image for an attachment via AJAX.
- wp_ajax_set_post_thumbnail()Handles setting the featured image via AJAX.
- wp_insert_post()Inserts or update a post.
- wp_xmlrpc_server::_insert_post()Helper method for wp_newPost() and wp_editPost(), containing shared logic.
- wp_xmlrpc_server::mw_editPost()Edits a post.
- wp_xmlrpc_server::mw_newPost()Creates a new post.
Source code
function set_post_thumbnail( $post, $thumbnail_id ) { $post = get_post( $post ); $thumbnail_id = absint( $thumbnail_id ); if ( $post && $thumbnail_id && get_post( $thumbnail_id ) ) { if ( wp_get_attachment_image( $thumbnail_id, 'thumbnail' ) ) { return update_post_meta( $post->ID, '_thumbnail_id', $thumbnail_id ); } else { return delete_post_meta( $post->ID, '_thumbnail_id' ); } } return false;}Changelog
Introduced in 3.1.0. 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 6.8.8 tag, from
src/wp-includes/post.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.