Overview
The Metadata API is a simple and standarized way for retrieving and manipulating metadata of various WordPress object types.
Metadata for an object is a represented by a simple key-value pair.
Objects may contain multiple metadata entries that share the same key and differ only in their value.
Function Reference
Add/Delete Metadata:
Get/Update Metadata:
Database Requirements
This function assumes that a dedicated MySQL table exists for the $meta_type you specify. Some desired $meta_types do not come with pre-installed WordPress tables, and so they must be created manually.
Default Meta Tables
Assuming a prefix of wp_, WordPress’s included meta tables are:
wp_commentmeta: Metadata for specific comments.wp_postmeta: Metadata for pages, posts, and all other post types.wp_usermeta: Metadata for users.
Meta Table Structure
To store data for meta types not included in the above table list, a new table needs to be created. All meta tables require four columns.
meta_id– BIGINT(20): unsigned, auto_increment, not null, primary key.object_id– BIGINT(20): unsigned, not null.
Replace object with the singular name of the content type being used.
For instance, this column might be named post_id or term_id.
Although this column is used like a foreign key, it should not be defined as one.meta_key– VARCHAR(255): The key of your custom meta data.meta_value– LONGTEXT: The value of your custom meta data.
Source File
Metadata API is located in wp-includes/meta.php.
Related
Metadata API: add_metadata(), get_metadata(), update_metadata(), delete_metadata().