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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

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)

meta_value 

LONGTEXT

Source File

• Metadata API is located in wp-includes/meta.php.

Related

Metadata API: add_metadata(), get_metadata(), update_metadata(), delete_metadata()