Adding Metaboxes in WordPress to your admin areas normally involves 3 steps:

Action to define the metabox area
Callback to define the metabox content
Action to handle the metabox updates / saves

This can be done much easier using Custom Metaboxes and Fields for WordPress, which is a metabox, custom fields and forms library. The library provides a bunch of custom fields and also allows you to add your own easily. Much easier to build new Metaboxes fast!

List of field types included:

title An arbitrary title field *
text
text_small
text_medium
text_email
text_url
text_money
textarea
textarea_small
textarea_code
text_date Date Picker
text_time Time picker
select_timezone Time zone dropdown
text_date_timestamp Date Picker (UNIX timestamp)
text_datetime_timestamp Text Date/Time Picker Combo (UNIX timestamp)
text_datetime_timestamp_timezone Text Date/Time Picker/Time zone Combo (serialized DateTime object)
colorpicker Color picker
radio *
radio_inline *
taxonomy_radio *
taxonomy_radio_inline *
select
taxonomy_select *
checkbox *
multicheck
taxonomy_multicheck *
taxonomy_multicheck_inline
wysiwyg (TinyMCE) *
file Image/File upload *†
file_list Image/File list upload
oembed Converts oembed urls (instagram, twitter, youtube, etc. oEmbed in the Codex)
group Hybrid field that supports adding other fields as a repeatable group. *

Simple example from the CMB2 Github page

if ( file_exists(  __DIR__ . '/cmb2/init.php' ) ) {
  require_once  __DIR__ . '/cmb2/init.php';
} elseif ( file_exists(  __DIR__ . '/CMB2/init.php' ) ) {
  require_once  __DIR__ . '/CMB2/init.php';
}

add_action( 'cmb2_init', 'cmb2_sample_metaboxes' );
/**
 * Define the metabox and field configurations.
 */
function cmb2_sample_metaboxes() {

// Start with an underscore to hide fields from custom fields list
    $prefix = '_yourprefix_';

/**
     * Initiate the metabox
     */
    $cmb = new_cmb2_box( array(
        'id'            => 'test_metabox',
        'title'         => __( 'Test Metabox', 'cmb2' ),
        'object_types'  => array( 'page', ), // Post type
        'context'       => 'normal',
        'priority'      => 'high',
        'show_names'    => true, // Show field names on the left
        // 'cmb_styles' => false, // false to disable the CMB stylesheet
        // 'closed'     => true, // Keep the metabox closed by default
    ) );

// Regular text field
    $cmb->add_field( array(
        'name'       => __( 'Test Text', 'cmb2' ),
        'desc'       => __( 'field description (optional)', 'cmb2' ),
        'id'         => $prefix . 'text',
        'type'       => 'text',
        'show_on_cb' => 'cmb2_hide_if_no_cats', // function should return a bool value
        // 'sanitization_cb' => 'my_custom_sanitization', // custom sanitization callback parameter
        // 'escape_cb'       => 'my_custom_escaping',  // custom escaping callback parameter
        // 'on_front'        => false, // Optionally designate a field to wp-admin only
        // 'repeatable'      => true,
    ) );

}

if ( file_exists( __DIR__ . '/cmb2/init.php' ) ) {

require_once __DIR__ . '/cmb2/init.php';

} elseif ( file_exists( __DIR__ . '/CMB2/init.php' ) ) {

require_once __DIR__ . '/CMB2/init.php';

}

add_action( 'cmb2_init', 'cmb2_sample_metaboxes' );

/**

* Define the metabox and field configurations.

function cmb2_sample_metaboxes() {

// Start with an underscore to hide fields from custom fields list

$prefix = '_yourprefix_';

/**

* Initiate the metabox

$cmb = new_cmb2_box( array(

'id' => 'test_metabox',

'title' => __( 'Test Metabox', 'cmb2' ),

'object_types' => array( 'page', ), // Post type

'context' => 'normal',

'priority' => 'high',

'show_names' => true, // Show field names on the left

// 'cmb_styles' => false, // false to disable the CMB stylesheet

// 'closed' => true, // Keep the metabox closed by default

) );

// Regular text field

$cmb->add_field( array(

'name' => __( 'Test Text', 'cmb2' ),

'desc' => __( 'field description (optional)', 'cmb2' ),

'id' => $prefix . 'text',

'type' => 'text',

'show_on_cb' => 'cmb2_hide_if_no_cats', // function should return a bool value

// 'sanitization_cb' => 'my_custom_sanitization', // custom sanitization callback parameter

// 'escape_cb' => 'my_custom_escaping', // custom escaping callback parameter

// 'on_front' => false, // Optionally designate a field to wp-admin only

// 'repeatable' => true,

) );

}

Doing Metaboxes in WordPress the easy way

Alexander