Meta Box Conditions

Both meta-boxes, and specific meta-box fields can be set to show only if a specific condition is met.

The condition key can be added to both a meta-box and a meta-box field.

condition:

  # This condition checks if a PHP Class has been defined.
  # Value to check must be the name of the PHP Class, including the namespace if any.
  class_exists: GeminiLabs/Pollux/Application

  # This condition checks if a PHP constant exists.
  # Value to check must be the name of the PHP constant.
  defined: WP_ENV

  # This condition checks if a PHP function has been defined.
  # Value to check must be the name of the PHP function you are checking for.
  function_exists: get_current_screen

  # This condition checks if a WordPress plugin is active.
  # This is similar to "is_plugin_active()" except it also checks for mu-plugins.
  # Value to check must be the name of the plugin sub-directory/file.
  is_plugin_active: site-reviews/site-reviews.php

  # This condition checks if a WordPress plugin is inactive or not installed.
  # Value to check must be the name of the plugin sub-directory/file.
  is_plugin_inactive: site-reviews/site-reviews.php

  # The following conditions only apply in meta-boxes assigned to the "page" post_type:

  # This condition checks if the current page has been assigned to the Front page in the WordPress Reading Settings.
  # Value to check must be either true or false .
  is_front_page: true

  # This condition checks if the current page has been assigned to the Posts page in the WordPress Reading Settings.
  # Value to check must be either true or false.
  is_home: true

  # This condition checks if the current page has been assigned a page template.
  # Value to check must be the name of the theme template PHP file.
  is_page_template: template-contact.php

You can also make meta-box field visibility dependant on whether or not another field has a value.

The depends key can only be added to a meta-box field.

# Value to check must be the name of another meta-box field
depends: field_key_to_check_value_of

Here is an example meta-box entry that demonstrates the use of the depends option:

seo_settings:
  title: SEO Settings
  fields:
    seo_enabled:
      type: checkbox
      name: Enable SEO?
    seo_title:
      depends: seo_enabled
      type: text
      name: SEO Title
    seo_keywords:
      depends: seo_enabled
      type: text
      name: SEO Keywords
    seo_description:
      depends: seo_enabled
      type: textarea
      name: SEO Description