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.
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:
- Metadata for specific comments.
- Metadata for pages, posts, and all other post types.
- 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...
- BIGINT(20), unsigned, auto_increment, not null, primary key.
- 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.
- Metadata API is located in onlyincludecodewp-includes/meta.php/code/onlyinclude
Link to the source code on http://core.trac.wordpress.org/browser/.
- (option) path to codetag/code (version) or codetrunk/code. This option is only used for a new function.br /Default: codetrunk/code -- trunk is the latest bleeding edge development version of WordPress.
Link to the stable version: pre检查到模板循环：模板:Trac/pre
Link to trunk: pre检查到模板循环：模板:Trac/pre