Meta Box Factory is a framework for creating WordPress meta boxes that you can add to any theme or plugin.

It keeps things simple.

$mb = new MetaBox(array(
	"title"   => "Mood Ring",
	"screens" => "page,post",
	"fields"  => array(
		"mood" => array(
			"label"   => "What mood is this?",
			"type"    => "select",
			"options" => array(
				"Excited", "Mellow", "Upset", "Comfortable"
			),
			"value"   => "Comfortable"
		)
	)
));

And helps them stay simple.

$mb = new MetaBox(array(
	"title"   => "Mood Ring",
	"screens" => "page,post",
	"context" => "side",
	"fields"  => array(
		"summary" => array(
			"label"       => "Summarize this post",
			"type"        => "textarea",
			"rows"        => 4,
			"max"         => 144,
			"placeholder" => "Leave blank for auto-summary"
		),
		"mood" => array(
			"label"   => "What mood is this? (check all that apply)",
			"type"    => "checkbox",
			"options" => array(
				"Excited", "Mellow", "Upset", "Comfortable"
			),
			"value"   => "Comfortable"
		)
	)
));

And it supports JSON.

$mb = MetaBox::load('mood-ring.json');

{
	"title"  : "Mood Ring",
	"screens": "page,post",
	"context": "side",
	"fields" : {
		"summary": {
			"label"      : "Summarize this post",
			"type"       : "textarea",
			"rows"       : 4,
			"max"        : 144,
			"placeholder": "Leave blank for auto-summary"
		},
		"mood": {
			"label"  : "What mood is this? (check all that apply}",
			"type"   : "checkbox",
			"options": ["Excited", "Mellow", "Upset", "Comfortable"],
			"value"  : "Comfortable"
		}
	}
}

Enjoy!

The secret to getting ahead is getting started. — Mark Twain

In your functions.php, include this framework.

require_once(TEMPLATEPATH.'/wp-meta-box-factory/meta-box-factory.php');

Now, create a new meta box.

$mb = new MetaBox();

That’s it! Of course, it won’t be visible anywhere, but that is easily amended.

$mb->add_screen('post');

Nice! Now it shows up whenever you add or edit a post. But it says “More” because you didn’t give it a title. So, give it a title.

$mb->set_title('Advanced');

You got it! You do the thing and it does the thing. Now, move it to the side.

$mb->set_context('side');

Excellent! Now, add a field, and call it “epilogue”.

$mb->add_field('epilogue', array(
	'label' => 'What happened next?'
));

You win!

Oh, but next time, write it with way less code.

$mb = new MetaBox(array(
	'screens' => 'post',
	'title'   => 'Advanced',
	'context' => 'side',
	'fields'  => array(
		'epilogue' => array(
			'label' => 'What happened next?'
		)
	)
));

I don't need to know everything, I just need to know where to find it, when I need it. — Albert Einstein

Each new meta box returns a series of chainable methods.

Sets the title of the meta box.

$mb->set_title($title);

• title (string): The title.

Sets the screen or screens on which to show the meta box.

$mb->add_screen($screen[, $screen]);

And, alternatively:

$mb->remove_screen($screen[, $screen]);

• screen (string): The name of any screen, which may be post, page, dashboard, link, attachment, or some other custom screen type.

Sets the part of the page on which to show the meta box.

$mb->set_context($context);

• context (string): The part of the page, which may be normal, advanced, or side. The default is advanced.

Sets the priority within the context where the boxes should show.

$mb->set_priority($priority);

• priority (string): The priority, which may be high, core, default, or low. The default is (wait for it…) default.

Adds a new field or fields to a meta box.

$mb->add_field($name, $field);

• $name (string): the name of the field when saving to or reading from the database.
• $field (array): the properties of the field.

Or, alternatively:

$mb->add_field($fields);

• $fields: (array), a list of fields when saving to or reading from the database.

$mb = MetaBox::load($path[, $relative_file]);

• $path (string): the path to the JSON file.
• $relative_file (string): A relative path to the JSON file. Listen, unless you’re saving files relative to the wp-admin directory, you’ll probably need to add __FILE__ here.

Knowing is not enough; we must apply. Willing is not enough; we must do. — Johann Wolfgang von Goethe

Need a custom input type?

$mb->add_field('magic', array(
	'type'  => 'some_custom_type'
));

Create one.

MetaBox::$create_field->some_custom_type = function ($name, $data) {
	// do stuff and return a string of HTML
};

• $name (string): the name of the field when saving to or reading from the database.
• $data (array): the properties of the field.

Thus far, text, textarea, password, select, checkbox, and color input types have been defined.