get_the_category( int|false $post_id = false ): WP_Term[]
- Since
- 0.71
- Source
wp-includes/category-template.php:77
Description
This tag may be used outside The Loop by passing a post ID as the parameter.
Note: This function only returns results from the default "category" taxonomy.
For custom taxonomies use get_the_terms().
Compatibility
- WordPress
- since 0.71
- 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
$post_idint|falseoptional- The post ID. Defaults to current post ID.Default:
false
Return value
WP_Term[]- Array of WP_Term objects, one for each category assigned to the post.
Performance profile
How much work a call to get_the_category() 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
- Scales with input
- Instructions
- 23–28
- Plugin surface
- 1 hook
- Called by
- 5
Reaches the database via get_post().
The body loops, so the work grows with what you pass in.
Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 34.
Third-party callbacks on 'get_the_categories' run inside this call, and their cost is not bounded by anything here.
5 places in core call this, so the cost is paid more often than your own code shows.
What it touches
- hookthird-party callbacks
apply_filters()called directly - querycontent query
get_post()one call below get_the_category() - cacheobject cache
wp_cache_add()one call below get_the_category()
Further down the call graph this can also reach option, serialize 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 · 2 distinct outcomes
One number would be a lie: the work depends on which branch runs. These are every distinct cost get_the_category() can have, taken from its control-flow graph on PHP 8.5.
| When | Instructions | Calls it makes |
|---|---|---|
| always | 23–24 | get_the_terms(), array_values(), array_keys(), apply_filters() |
| always | 26–28 | get_the_terms(), is_wp_error(), array_values(), array_keys(), 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: 34 instructions, 23–28 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.
Hooks and filters fired · 1
One hook fires while get_the_category() runs, in this order:
- apply_filters( get_the_categories )filterline 98 (+21 into the body)
Filters the array of categories to return for a post.
Uses · 4
- get_the_terms()Retrieves the terms of the taxonomy that are attached to the post.
- is_wp_error()Checks whether the given variable is a WordPress Error.
- _make_cat_compat()Updates category structure to old pre-2.3 from new taxonomy structure.
- apply_filters()Calls the callback functions that have been added to a filter hook.
Used by · 5
- get_permalink()Retrieves the full permalink for the current post or post ID.
- get_the_category_list()Retrieves category list for a post in either HTML list or custom format.
- get_the_category_rss()Retrieves all of the post categories, formatted for use in feeds.
- the_category_ID()Returns or prints a category ID.
- the_category_head()Prints a category with optional text before and after.
Source code
function get_the_category( $post_id = false ) { $categories = get_the_terms( $post_id, 'category' ); if ( ! $categories || is_wp_error( $categories ) ) { $categories = array(); } $categories = array_values( $categories ); foreach ( array_keys( $categories ) as $key ) { _make_cat_compat( $categories[ $key ] ); } /** * Filters the array of categories to return for a post. * * @since 3.1.0 * @since 4.4.0 Added the `$post_id` parameter. * * @param WP_Term[] $categories An array of categories to return for the post. * @param int|false $post_id The post ID. */ return apply_filters( 'get_the_categories', $categories, $post_id );}Changelog
Introduced in 0.71. One change between 6.7.7 and 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
$post_id retyped from int to int|false.verified against sourceAbout this page
- Parsed data
- Generated from the wordpress-develop 7.1.0 tag, from
src/wp-includes/category-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.