Post Options API

Howdy and welcome to the Post Options API, an alternative approach at Custom Fields in WordPress. The API makes it extremely easy to show different kinds of extra fields to posts, pages and custom post types in WordPress, with nice looking meta boxes and a whole set of predefined callback functions to generate controls like checkboxes, text fields and more, although you can always use your custom callback.

If you're familiar with WordPress' Settings API you'll find this extremely easy to use, except of course for the object/classes madness that we created. Let me explain.

Compatibility Approach

To ensure compatibility with other themes and plugins that might be using the Post Options API (perhaps a different version) we've built in two initialization functions -- get_post_options_api to retrieve the API itself and get_post_options_api_fields to retrieve the fields helper. Here's how you use them:

function your_function() {
	
	// Initialize Post Options API
	require( dirname( __FILE__ ) . '/inc/post-options-api.1.0.php' );
	$post_options = get_post_options_api( '1.0' );
	$post_fields = get_post_options_api_fields( '1.0' );
}

add_action( 'init', 'your_function' );

And then you can use the $post_options and $post_fields objects like you normally would, i.e.:

$post_options->register_post_options_section( ... );
$post_options->add_section_to_post_type( ... );
$post_options->register_post_option( 
	...
	'callback' => $post_fields->checkbox( ... )
);

Hope this explains it and doesn't make it too crazy to use, but we really had to go this way to ensure that the same version is always one, i.e. the class is a singleton, never redefined and never initialized twice (unless you explicitly ask it to of course).

Usage

Grab the latest stable post-options-api.x.php file from the lib directory, where x is a version number. Memorize that version number since you'll need it later on. Copy the file into an include directory in your WordPress theme or plugin, typically called inc. In your theme's functions.php file or your plugin source file during the WordPress init action, load that file and initialize the two objects. I have shown this in the snippet above, but here you go again:

function your_function() {

	// Initialize Post Options API
	require( dirname( __FILE__ ) . '/inc/post-options-api.1.0.php' );
	$post_options = get_post_options_api( '1.0' );
	$post_fields = get_post_options_api_fields( '1.0' );
	
	// Add the fields here
}

add_action( 'init', 'your_function' );

And 1.0 is that version number you should have memorized. It will return a WP_Error if the requested version does not exist so you might want to do a check for is_wp_error() before going on, but if you're bundling the API together with your theme or plugin that should never be the case.

Examples

There's an example directory which you can check out. It's basically a plugin that ads a bunch of options to posts and pages in WordPress. Copy the plugin directory into your wp-content/plugins folder and activate it in the WordPress dashboard. You'll see the the madness going on in your Edit Post and Edit Page screens. To find out how that madness has been created inspect the plugin source files. It's quite easy to understand and follow along.

Questions?

Good luck using this and if you have any questions, feel free to contact me at kovshenin@gmail.com or kovshenin on Skype. Cheers!