get_post_meta( int $post_id, string $key = '', bool $single = false )
Retrieve post meta field for a post.
Contents
Description Description
Parameters Parameters
- $post_id
-
(int) (Required) Post ID.
- $key
-
(string) (Optional) The meta key to retrieve. By default, returns data for all keys.
Default value: ''
- $single
-
(bool) (Optional) Whether to return a single value.
Default value: false
Return Return
(mixed) Will be an array if $single is false. Will be value of meta data field if $single is true.
Source Source
File: wp-includes/post.php
function get_post_meta( $post_id, $key = '', $single = false ) {
return get_metadata('post', $post_id, $key, $single);
}
Expand full source code Collapse full source code View on Trac
Changelog Changelog
| Version | Description |
|---|---|
| 1.5.0 | Introduced. |
More Information More Information
- Please note that if a db collation is case insensitive (has with suffix _ci) then update_post_meta and delete_post_meta and get_posts() will update/delete/query the meta records with keys that are upper or lower case. However get_post_meta will apparently be case sensitive due to WordPress caching. See https://core.trac.wordpress.org/ticket/18210 for more info. Be careful not to mix upper and lowercase.
- Uses: get_metadata() to retrieve the metadata.
User Contributed Notes User Contributed Notes
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Return values when no meta field is found
If a meta field with the given $key isn’t found for the given $post_id, the return value varies:
If $single is true, an empty string is returned.
If $single is false, an empty array is returned.
Since both evaluate as false, you can use get_post_meta directly in conditionals, like this:
if( ! get_post_meta( '1', 'non-existing_meta', true ) ) {} if( ! get_post_meta( '1', 'non-existing_meta', false ) ) {} // both ifs will get run if no meta field is found; since // array() == false and '' == falseWhat if I want to store an empty string?
If for some reason your with to store an empty string or array into your meta field, get_post_meta will not be reliable when checking if the given meta field exists.
In this case, you can use get_post_custom_keys to do so:
if( ! in_array( 'given_key', get_post_custom_keys( '1' ) ) ) {} // this correctly checks for the existence of the given key, // even if it's empty or has a value that evaluates as false.Show the first value of the specified key inside a loop
$key_1_value = get_post_meta( get_the_ID(), 'key_1', true ); // Check if the custom field has a value. if ( ! empty( $key_1_value ) ) { echo $key_1_value; }Default Usage
Get the meta for all keys for the current post:
Get all meta for a single key for the current post:
Get the first value of a meta key for the current post:
The best thing about this function is that you no longer need to use it :)
Since r21559 (v3.5), you can just call
$post->footo fetch the equivalent ofget_post_meta( $post->ID, 'foo', true ).You can even extend that to introduce dynamically-generated fields, so you can call
echo esc_html( $post->bar )instead of$bar = some_custom_logic( get_post_meta( $post->ID, 'bar', true ) ); echo esc_html( $bar ).This makes code a lot cleaner and more readable.
add_filter( 'get_post_metadata', 'add_dynamic_post_meta', 10, 4 ); /** * Add dynamically-generated "post meta" to `\WP_Post` objects * * This makes it possible to access dynamic data related to a post object by simply referencing `$post->foo`. * That keeps the calling code much cleaner than if it were to have to do something like * `$foo = some_custom_logic( get_post_meta( $post->ID, 'bar', true ) ); echo esc_html( $foo )`. * * @param mixed $value * @param int $post_id * @param string $meta_key * @param int $single @todo handle the case where this is false * * @return mixed * `null` to instruct `get_metadata()` to pull the value from the database * Any non-null value will be returned as if it were pulled from the database */ function add_dynamic_post_meta( $value, $post_id, $meta_key, $single ) { $post = get_post( $post_id ); if ( 'page' != $post->post_type ) { return $value; } switch ( $meta_key ) { case 'verbose_page_template': $value = "The page template is " . ( $post->_wp_page_template ?: 'not assigned' ); break; } return $value; }Expand full source codeCollapse full source code
Retrieve a Custom Field Thumbnail Url
While you are in the WordPress Loop, you can use this code to retrieve a custom field. In this example, the thumbnail image url is in a custom field named “thumb”.
If you want to hide postmeta keys from the customfields prefix the key name with an underscore.
Post meta keys are case-sensitive
When you don’t specify a $key (”) and set $single to true in get_post_meta, it will return all keys still with an array of values.
Display single meta value using meta key
If the value of the
$keyparameter is falsyget_post_metawill return the entire post meta array, even if$singleis set totrue. for example:False if post ID isn’t absint or is 0
Passing
$post_id == 0(or anything not a absint) will return false no matter$single.When I had tons of meta keys to work with to display some custom content for custom post types, instead of making several dozen calls to the get_post_meta function to grab the keys I wanted, I wrote this function instead. Basically it gets all of the meta keys and filters out all of the arrays with single values while maintaining any arrays that actually do have multiple values and returns an associative array of the results. If you have lots of single values to get, it saves you from having to iterate over every result to get your $k=>$v pairs so you can just access them by $mk[‘my_custom_meta_key’].
function array_push_assoc($array, $key, $value){$array[$key] = $value;
return $array;
}
function filter_gpm($array){
$mk = array();
foreach($array as $k => $v){
if(is_array($v) && count($v) == 1){
$mk = array_push_assoc($mk, $k, $v[0]);
} else {
$mk = array_push_assoc($mk, $k, $v);
}
}
return $mk;
}
Call it like so
$mk = filter_gpm( get_post_meta( get_the_ID() ) );