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WordPress

get_post_meta( int $post_id, string $key = '', bool $single = false ): mixed

Since
1.5.0
Source
wp-includes/post.php:2750

Read a post's custom field with get_post_meta(); pass true as the third argument to get one value instead of an array of every value for the key. Omitting $key returns all meta for the post. A missing key yields an empty string (single) or an empty array, and non-serialized scalars are returned as strings.

Retrieves a post meta field for the given post ID.

Compatibility

WordPress
since 1.5.0
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

$post_idint
Post ID.
$keystringoptional
The meta key to retrieve. By default, returns data for all keys. Default empty.Default: ''
$singlebooloptional
Whether to return a single value.
This parameter has no effect if $key is not specified.
Default false.Default: false

Return value

mixed
An array of values if $single is false.
The value of the meta field if $single is true.
False for an invalid $post_id (non-numeric, zero, or negative value).
An empty array if a valid but non-existing post ID is passed and $single is false.
An empty string if a valid but non-existing post ID is passed and $single is true.
Note: Non-serialized values are returned as strings:
- false values are returned as empty strings ('')
- true values are returned as '1'
- numbers (both integer and float) are returned as strings Arrays and objects retain their original type.

Code examples

Every example is editable and runs in a real WordPress booted in your browser by WordPress Playground. Press Run, then edit the code: clicking away re-runs it. Nothing is sent anywhere until you do.

Get a single custom field value

Passing true for $single returns the value itself rather than an array of every row.

$price = get_post_meta( 2, 'price', true );

if ( '' !== $price ) {
	echo 'Price: ', esc_html( $price );
} else {
	echo 'That post has no price set.';
}

A missing key returns an empty string with $single true, and an empty array without it.

Read every value stored under one key

A key can hold many rows; omitting $single gives you all of them in the order they were stored.

delete_post_meta( 3, 'ticket_url' );
add_post_meta( 3, 'ticket_url', 'https://example.com/early-bird' );
add_post_meta( 3, 'ticket_url', 'https://example.com/general' );

$urls = get_post_meta( 3, 'ticket_url' );

print_r( $urls );

add_post_meta() appends a row; update_post_meta() replaces one.

Performance profile

How much work a call to get_post_meta() 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
Trivial

Touches nothing outside its own arguments.

Scaling
Constant

No loop in the body: the same number of instructions runs whatever you pass in.

Instructions
10

Executed per call on PHP 8.5. The body compiles to 10.

Plugin surface
None

Nothing here hands control to plugin code.

Called by
50

50 places in core call this, so the cost is paid more often than your own code shows.

What one call costs · 1 distinct outcome

One number would be a lie: the work depends on which branch runs. These are every distinct cost get_post_meta() can have, taken from its control-flow graph on PHP 8.5.

WhenInstructionsCalls it makes
always10get_metadata()

Across PHP versions

Compiles the same on PHP 7.4, 8.1, 8.2, 8.3, 8.4, 8.5 and 8.6-dev: 10 instructions, 10 executed per call, 0 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 · 1

  • get_metadata()Retrieves the value of a metadata field for the specified object type and ID.

Used by · 50

Show all 50

Source code

View on Trac View on GitHub 

function get_post_meta( $post_id, $key = '', $single = false ) {	return get_metadata( 'post', $post_id, $key, $single );}

Changelog

Introduced in 1.5.0. Unchanged from 6.7.7 through 7.1.0.

  1. 6.7.7
  2. 6.8.8
  3. 6.9.7
  4. 7.0.4
  5. 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/post.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.
Corrections
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