Adding your own field types

Justin Sternberg edited this page Aug 1, 2017 · 82 revisions

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This library contains a couple of hooks that make it possible for you to create and properly save your own field types:

  • cmb2_render_{field-type}
  • cmb2_sanitize_{field-type}

You can add actions and filters to these hooks (using WordPress's native add_action() and add_filter() functions) that enable the custom field types.

Example 1: Email field

This field is included in CMB2, so consider this tutorial simply an example.

A good example would be a text_email field that only allowed users to enter a valid email address.

Screenshot

Step 1: cmb2_render_{field-type}

The first step is to write the code for rendering the field within the WordPress administrative area:

function cmb2_render_callback_for_text_email( $field, $escaped_value, $object_id, $object_type, $field_type_object ) {
	echo $field_type_object->input( array( 'type' => 'email' ) );
}
add_action( 'cmb2_render_text_email', 'cmb2_render_callback_for_text_email', 10, 5 );

This snippet has a few things going on:

  • cmb2_render_text_email -- By adding an action to this hook, we are essentially creating the new field type. This action defines what code gets executed when you add the text_email field type in your field configuration. This first parameter, the hook name, must be cmb2_render_ followed by the field type name.

  • cmb2_render_callback_for_text_email -- This is the name of your custom function that gets executed when you use the text_email field type. It can be called whatever you want, but it must match a function you define elsewhere in your code.

  • 10 -- This is the priority for this action, the order in which it is executed. 10 should be your default unless you have a very good reason for changing it.

  • 5 -- This is the number of arguments your custom function will receive. It is required to specify the priority parameter as well as this parameter if you want the callback function to receive more than 1 argument (which is the default). This hook can pass up to 5 arguments:

    • $field: The current CMB2_Field object.
    • $escaped_value: The value of this field passed through the escaping filter. It defaults to sanitize_text_field. If you need the unescaped value, you can access it via $field_type_object->value().
    • $object_id: The id of the object you are working with. Most commonly, the post id.
    • $object_type: The type of object you are working with. Most commonly, post (this applies to all post-types), but could also be comment, user or options-page.
    • $field_type_object: This is an instance of the CMB2_Types object and gives you access to all of the methods that CMB2 uses to build its field types.

    We needed to request 5 arguments so that we could access the $field_type_object argument in particular. This allows us to use CMB2's built in input method.

In this example, our custom field type will display a normal CMB2 input box, but with a type attribute of email. It will display the value previously specified for the field, if there is one, and generally work the same as any other CMB2 text* fields.

Step 2: cmb2_sanitize_{field-type}

You can optionally add code that sanitizes or modifies the entered value before it is saved. In our example, we only want to allow valid email addresses; we can remove any invalid values before they are saved to the database.

Note: in most modern browsers, the field will not be allowed to submit if using the email attribute and the value is not an email, but we're including the sanitization filter as a fallback for older browsers.

function cmb2_sanitize_text_email_callback( $override_value, $value ) {
	// not an email?
	if ( ! is_email( $value ) ) {
		// Empty the value
		$value = '';
	}
	return $value;
}
add_filter( 'cmb2_sanitize_text_email', 'cmb2_sanitize_text_email_callback', 10, 2 );

What's going on:

  • cmb2_sanitize_text_email -- This filter defines what code gets executed when the user attempts to save a value in a field type called text_email in the library. This first parameter, the hook name, must be cmb2_sanitize_ followed by the field type name.
  • cmb2_sanitize_text_email_callback -- This is the name of your custom function that gets executed when the user attempts to save a value in a field type called text_email. It can be called whatever you want, but it must match a function you define elsewhere in your code.

The cmb2_sanitize_{field-type} hook can pass up to 5 arguments:

  • $override_value: Sanitization override value to return. It is passed in as null, and is what we will modify to short-circuit CMB2's saving mechanism.
  • $value: The actual field value.
  • $object_id: The id of the object you are working with. Most commonly, the post id.
  • $field_args: The field arguments.
  • $sanitizer_object: This is an instance of the CMB2_Sanitize object and gives you access to all of the methods that CMB2 uses to sanitize its field values.

When the user attempts to save a value in the field, we will check if the new value is a valid email address. If not, we will set it as empty. We will then return the possibly-modified value back to the library to do the saving.

Step 3: Use the field type

With the action (and optionally the filter) added, we can now use the field type in our code just like we would use the built-in field types.

function cmb2_text_email_metabox() {

	$cmb = new_cmb2_box( array(
		'id'           => 'cmb2_text_email_metabox',
		'title'        => 'Person Information',
		'object_types' => array( 'post' ),
	) );

	$cmb->add_field( array(
		'name' => 'Email',
		'id'   => '_cmb2_person_email',
		'type' => 'text_email',
		'desc' => 'Invalid email addresses will be wiped out.',
	) );

}
add_action( 'cmb2_admin_init', 'cmb2_text_email_metabox' );

Screenshot

Example 2: Posts (or other post_type) Dropdown, store post_id

For the times when you need to relate one post to another, this comes in handy.

Like the terms field above, we would pass an array of posts to the select field type. First we'll create a function to pull back an array of post options:

/**
 * Gets a number of posts and displays them as options
 * @param  array $query_args Optional. Overrides defaults.
 * @return array             An array of options that matches the CMB2 options array
 */
function cmb2_get_post_options( $query_args ) {

	$args = wp_parse_args( $query_args, array(
		'post_type'   => 'post',
		'numberposts' => 10,
	) );

	$posts = get_posts( $args );

	$post_options = array();
	if ( $posts ) {
		foreach ( $posts as $post ) {
          $post_options[ $post->ID ] = $post->post_title;
		}
	}

	return $post_options;
}

/**
 * Gets 5 posts for your_post_type and displays them as options
 * @return array An array of options that matches the CMB2 options array
 */
function cmb2_get_your_post_type_post_options() {
	return cmb2_get_post_options( array( 'post_type' => 'your_post_type', 'numberposts' => 5 ) );
}

Then, when creating our field, we would add the multicheck type and use cmb2_get_your_post_type_post_options as a callback function to the 'options_cb' field parameter. Using the callback this way ensures that the query ONLY happens when the field is called (rather than on every page-load).

$cmb_demo->add_field( array(
	'name'       => __( 'Select your_post_type Posts', 'cmb2' ),
	'desc'       => __( 'field description (optional)', 'cmb2' ),
	'id'         => $prefix . 'post_multicheckbox',
	'type'       => 'multicheck',
	'options_cb' => 'cmb2_get_your_post_type_post_options',
) );

Alternatively, you could use the multicheck, or radio field types as well.

if you're looking for a similar solution for saving a term_id (or term_ids), read about it on the Tips & Tricks page.

Example 4: Multiple Inputs, One Field. Let's Create an Address Field.

Update This is now available as a plugin in the CMB2 Snippet Library

You may want to create your own field type that stores multiple inputs. Here's how you could create an address field type:

/**
 * Returns options markup for a state select field.
 * @param  mixed $value Selected/saved state
 * @return string       html string containing all state options
 */
function cmb2_get_state_options( $value = false ) {
	$state_list = array( 'AL'=>'Alabama','AK'=>'Alaska','AZ'=>'Arizona','AR'=>'Arkansas','CA'=>'California','CO'=>'Colorado','CT'=>'Connecticut','DE'=>'Delaware','DC'=>'District Of Columbia','FL'=>'Florida','GA'=>'Georgia','HI'=>'Hawaii','ID'=>'Idaho','IL'=>'Illinois','IN'=>'Indiana','IA'=>'Iowa','KS'=>'Kansas','KY'=>'Kentucky','LA'=>'Louisiana','ME'=>'Maine','MD'=>'Maryland','MA'=>'Massachusetts','MI'=>'Michigan','MN'=>'Minnesota','MS'=>'Mississippi','MO'=>'Missouri','MT'=>'Montana','NE'=>'Nebraska','NV'=>'Nevada','NH'=>'New Hampshire','NJ'=>'New Jersey','NM'=>'New Mexico','NY'=>'New York','NC'=>'North Carolina','ND'=>'North Dakota','OH'=>'Ohio','OK'=>'Oklahoma','OR'=>'Oregon','PA'=>'Pennsylvania','RI'=>'Rhode Island','SC'=>'South Carolina','SD'=>'South Dakota','TN'=>'Tennessee','TX'=>'Texas','UT'=>'Utah','VT'=>'Vermont','VA'=>'Virginia','WA'=>'Washington','WV'=>'West Virginia','WI'=>'Wisconsin','WY'=>'Wyoming' );

	$state_options = '';
	foreach ( $state_list as $abrev => $state ) {
		$state_options .= '<option value="'. $abrev .'" '. selected( $value, $abrev, false ) .'>'. $state .'</option>';
	}

	return $state_options;
}

/**
 * Render Address Field
 */
function cmb2_render_address_field_callback( $field, $value, $object_id, $object_type, $field_type ) {

	// make sure we specify each part of the value we need.
	$value = wp_parse_args( $value, array(
		'address-1' => '',
		'address-2' => '',
		'city'      => '',
		'state'     => '',
		'zip'       => '',
	) );

	?>
	<div><p><label for="<?php echo $field_type->_id( '_address_1' ); ?>">Address 1</label></p>
		<?php echo $field_type->input( array(
			'name'  => $field_type->_name( '[address-1]' ),
			'id'    => $field_type->_id( '_address_1' ),
			'value' => $value['address-1'],
			'desc'  => '',
		) ); ?>
	</div>
	<div><p><label for="<?php echo $field_type->_id( '_address_2' ); ?>'">Address 2</label></p>
		<?php echo $field_type->input( array(
			'name'  => $field_type->_name( '[address-2]' ),
			'id'    => $field_type->_id( '_address_2' ),
			'value' => $value['address-2'],
			'desc'  => '',
		) ); ?>
	</div>
	<div class="alignleft"><p><label for="<?php echo $field_type->_id( '_city' ); ?>'">City</label></p>
		<?php echo $field_type->input( array(
			'class' => 'cmb_text_small',
			'name'  => $field_type->_name( '[city]' ),
			'id'    => $field_type->_id( '_city' ),
			'value' => $value['city'],
			'desc'  => '',
		) ); ?>
	</div>
	<div class="alignleft"><p><label for="<?php echo $field_type->_id( '_state' ); ?>'">State</label></p>
		<?php echo $field_type->select( array(
			'name'    => $field_type->_name( '[state]' ),
			'id'      => $field_type->_id( '_state' ),
			'options' => cmb2_get_state_options( $value['state'] ),
			'desc'    => '',
		) ); ?>
	</div>
	<div class="alignleft"><p><label for="<?php echo $field_type->_id( '_zip' ); ?>'">Zip</label></p>
		<?php echo $field_type->input( array(
			'class' => 'cmb_text_small',
			'name'  => $field_type->_name( '[zip]' ),
			'id'    => $field_type->_id( '_zip' ),
			'value' => $value['zip'],
			'type'  => 'number',
			'desc'  => '',
		) ); ?>
	</div>
	<br class="clear">
	<?php
	echo $field_type->_desc( true );

}
add_filter( 'cmb2_render_address', 'cmb2_render_address_field_callback', 10, 5 );

If you use the built-in $field_type_object field-type functionality, it is much more likely your custom field type will work with other CMB2 features, and often can save you some hassle.

Setup the field

To register this new field type:

...
	'fields' => array(
		array(
			'name' => 'Address',
			'desc' => 'Custom Address Field',
			'id'   => '_cmb2_person_address',
			'type' => 'address',
		),
	),
...

Use the field in your template

If you wanted to display this address in your theme or plugin, you could do it like:

$post_id = get_the_ID();
$address = get_post_meta( $post_id, $prefix . 'address', 1 );

// Set default values for each address key
$address = wp_parse_args( $address, array(
	'address-1' => '',
	'address-2' => '',
	'city'      => '',
	'state'     => '',
	'zip'       => '',
) );

?>
<p><strong>Address:</strong> <?php echo esc_html( $address['address-1'] ); ?></p>
<?php if ( $address['address-2'] ) : ?>
	<p><strong>Address 2:</strong> <?php echo esc_html( $address['address-2'] ); ?></p>
<?php endif; ?>
<p><strong>City:</strong> <?php echo esc_html( $address['city'] ); ?></p>
<p><strong>State:</strong> <?php echo esc_html( $address['state'] ); ?></p>
<p><strong>Zip:</strong> <?php echo esc_html( $address['zip'] ); ?></p>
<?php

Note: It was asked how to make this field repeatable. It's not impossible, but it's also not super simple.

Add Your Own Examples

The possibilities are endless. If you create custom field types that you think others would find useful, please share them here!

text_number - adds a text number input

Sometimes you only want a number in your input.

// render numbers
add_action( 'cmb2_render_text_number', 'sm_cmb_render_text_number', 10, 5 );
function sm_cmb_render_text_number( $field, $escaped_value, $object_id, $object_type, $field_type_object ) {
	echo $field_type_object->input( array( 'class' => 'cmb2-text-small', 'type' => 'number' ) );
}

// sanitize the field
add_filter( 'cmb2_sanitize_text_number', 'sm_cmb2_sanitize_text_number', 10, 2 );
function sm_cmb2_sanitize_text_number( $null, $new ) {
	$new = preg_replace( "/[^0-9]/", "", $new );

	return $new;
}

multicheck_posttype - adds a multicheck for post type

//By Daniele Mte90 Scasciafratte
// render multicheck-posttype
add_action( 'cmb2_render_multicheck_posttype', 'cmb_render_multicheck_posttype', 10, 5 );

function cmb_render_multicheck_posttype( $field, $escaped_value, $object_id, $object_type, $field_type_object ) {
	$cpts = get_post_types();
	unset( $cpts[ 'nav_menu_item' ] );
	unset( $cpts[ 'revision' ] );
	$options = '';
	$i = 1;
	$values = (array) $escaped_value;
	
	if ( $cpts ) {
		foreach ( $cpts as $cpt ) {
			$args = array(
			    'value' => $cpt,
			    'label' => $cpt,
			    'type' => 'checkbox',
			    'name' => $field->args['_name'] . '[]',
			);

			if ( in_array( $cpt, $values ) ) {
				$args[ 'checked' ] = 'checked';
			}
			$options .= $field_type_object->list_input( $args, $i );
			$i++;
		}
	}

	$classes = false === $field->args( 'select_all_button' ) ? 'cmb2-checkbox-list no-select-all cmb2-list' : 'cmb2-checkbox-list cmb2-list';
	echo $field_type_object->radio( array( 'class' => $classes, 'options' => $options ), 'multicheck_posttype' );
}

Autocomplete type removed as it did not work during testing.

Other Resources

Documentation:

  1. Home

  2. Installation
    Installation instructions for various environments

  3. Basic Usage
    Get up and running

  4. Advanced Usage
    Not for the faint of heart

  5. Field Types
    Breakdown of field types

  6. Examples
    Examples for registering fields

  7. Field Parameters
    Breakdown of common field parameters

  8. Display Options
    Limit display of boxes

  9. Box Properties
    Breakdown of box properties

  10. Troubleshooting
    Common issues & how to deal with them

  11. Notable Changes in CMB2 (from original CMB)
    CMB2 — a complete re-write

  12. Tips & Tricks
    10x your CMB2 skills

  13. REST API
    CMB2 data through WordPress REST API

  14. Javascript API
    Work with CMB2 JS events & hooks

Advanced tutorials:

External Resources:

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