WordPress开发函数add_meta_box()
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WordPress开发函数add_meta_box()，添加一个元框到一个或多个屏幕。 用法： add_met…
WordPress开发函数add_meta_box()，添加一个元框到一个或多个屏幕。
用法：
add_meta_box( string $id, string $title, callable $callback, string|array|WP_Screen $screen = null, string $context = ‘advanced’, string $priority = ‘default’, array $callback_args = null )
参数：
$id
(string) (必需) 元框ID(在元框的’ ID ‘属性中使用)。
$title
(string) (必需) 元框的标题。
$callback
(callable) (必需) 函数，用所需的内容填充框。函数应该回显它的输出。
$screen
(string|array|WP_Screen) (可选) 显示框的屏幕(如帖子类型、“链接”或“评论”)。接受单个屏幕ID、WP_Screen对象或屏幕ID数组。默认是当前屏幕。如果您已经使用了add_menu_page()或add_submenu_page()来创建一个新屏幕(以及screen_id)，请确保您的菜单段符合sanitie_key()的限制，否则“屏幕”菜单可能不能正确地在您的页面上呈现。
默认值: null
$context
(string) (可选) 框应该显示在屏幕内的上下文。可用的上下文因屏幕而异。Post edit屏幕上下文包括“普通”、“边”和“高级”。评论屏幕上下文包括“正常”和“边”。菜单元框(手风琴部分)都使用’side’上下文。全球
默认值: ‘advanced’
$priority
(string) (可选) 方框应该显示的上下文中的优先级。接受’high’， ‘core’， ‘default’，或’low’。
默认值: ‘default’
$callback_args
(array) (可选) 数据，应该设置为box数组的$args属性(这是传递给回调函数的第二个参数)。
默认值: null
来源：
文件: wp-admin/includes/template.php
function add_meta_box( $id, $title, $callback, $screen = null, $context = ‘advanced’, $priority = ‘default’, $callback_args = null ) {
global $wp_meta_boxes;
if ( empty( $screen ) ) {
$screen = get_current_screen();
} elseif ( is_string( $screen ) ) {
$screen = convert_to_screen( $screen );
} elseif ( is_array( $screen ) ) {
foreach ( $screen as $single_screen ) {
add_meta_box( $id, $title, $callback, $single_screen, $context, $priority, $callback_args );
}
}
if ( ! isset( $screen->id ) ) {
return;
}
$page = $screen->id;
if ( ! isset( $wp_meta_boxes ) ) {
$wp_meta_boxes = array();
}
if ( ! isset( $wp_meta_boxes[ $page ] ) ) {
$wp_meta_boxes[ $page ] = array();
}
if ( ! isset( $wp_meta_boxes[ $page ][ $context ] ) ) {
$wp_meta_boxes[ $page ][ $context ] = array();
}
foreach ( array_keys( $wp_meta_boxes[ $page ] ) as $a_context ) {
foreach ( array( ‘high’, ‘core’, ‘default’, ‘low’ ) as $a_priority ) {
if ( ! isset( $wp_meta_boxes[ $page ][ $a_context ][ $a_priority ][ $id ] ) ) {
continue;
}
// If a core box was previously removed, don’t add.
if ( ( ‘core’ === $priority || ‘sorted’ === $priority )
&& false === $wp_meta_boxes[ $page ][ $a_context ][ $a_priority ][ $id ]
) {
return;
}
// If a core box was previously added by a plugin, don’t add.
if ( ‘core’ === $priority ) {
/*
* If the box was added with default priority, give it core priority
* to maintain sort order.
*/
if ( ‘default’ === $a_priority ) {
$wp_meta_boxes[ $page ][ $a_context ][‘core’][ $id ] = $wp_meta_boxes[ $page ][ $a_context ][‘default’][ $id ];
unset( $wp_meta_boxes[ $page ][ $a_context ][‘default’][ $id ] );
}
return;
}
// If no priority given and ID already present, use existing priority.
if ( empty( $priority ) ) {
$priority = $a_priority;
/*
* Else, if we’re adding to the sorted priority, we don’t know the title
* or callback. Grab them from the previously added context/priority.
*/
} elseif ( ‘sorted’ === $priority ) {
$title = $wp_meta_boxes[ $page ][ $a_context ][ $a_priority ][ $id ][‘title’];
$callback = $wp_meta_boxes[ $page ][ $a_context ][ $a_priority ][ $id ][‘callback’];
$callback_args = $wp_meta_boxes[ $page ][ $a_context ][ $a_priority ][ $id ][‘args’];
}
// An ID can be in only one priority and one context.
if ( $priority !== $a_priority || $context !== $a_context ) {
unset( $wp_meta_boxes[ $page ][ $a_context ][ $a_priority ][ $id ] );
}
}
}
if ( empty( $priority ) ) {
$priority = ‘low’;
}
if ( ! isset( $wp_meta_boxes[ $page ][ $context ][ $priority ] ) ) {
$wp_meta_boxes[ $page ][ $context ][ $priority ] = array();
}
$wp_meta_boxes[ $page ][ $context ][ $priority ][ $id ] = array(
‘id’ => $id,
‘title’ => $title,
‘callback’ => $callback,
‘args’ => $callback_args,
);
}
更新日志：
用户贡献的笔记
（由Codex – 6年前贡献）
类
这是一个如何在类内部添加元框的例子
/**
* Calls the class on the post edit screen.
*/
function call_someClass() {
new someClass();
}
if ( is_admin() ) {
add_action( ‘load-post.php’, ‘call_someClass’ );
add_action( ‘load-post-new.php’, ‘call_someClass’ );
}
/**
* The Class.
*/
class someClass {
/**
* Hook into the appropriate actions when the class is constructed.
*/
public function __construct() {
add_action( ‘add_meta_boxes’, array( $this, ‘add_meta_box’ ) );
add_action( ‘save_post’, array( $this, ‘save’ ) );
}
/**
* Adds the meta box container.
*/
public function add_meta_box( $post_type ) {
// Limit meta box to certain post types.
$post_types = array( ‘post’, ‘page’ );
if ( in_array( $post_type, $post_types ) ) {
add_meta_box(
‘some_meta_box_name’,
__( ‘Some Meta Box Headline’, ‘textdomain’ ),
array( $this, ‘render_meta_box_content’ ),
$post_type,
‘advanced’,
‘high’
);
}
}
/**
* Save the meta when the post is saved.
*
* @param int $post_id The ID of the post being saved.
*/
public function save( $post_id ) {
/*
* We need to verify this came from the our screen and with proper authorization,
* because save_post can be triggered at other times.
*/
// Check if our nonce is set.
if ( ! isset( $_POST[‘myplugin_inner_custom_box_nonce’] ) ) {
return $post_id;
}
$nonce = $_POST[‘myplugin_inner_custom_box_nonce’];
// Verify that the nonce is valid.
if ( ! wp_verify_nonce( $nonce, ‘myplugin_inner_custom_box’ ) ) {
return $post_id;
}
/*
* If this is an autosave, our form has not been submitted,
* so we don’t want to do anything.
*/
if ( defined( ‘DOING_AUTOSAVE’ ) && DOING_AUTOSAVE ) {
return $post_id;
}
// Check the user’s permissions.
if ( ‘page’ == $_POST[‘post_type’] ) {
if ( ! current_user_can( ‘edit_page’, $post_id ) ) {
return $post_id;
}
} else {
if ( ! current_user_can( ‘edit_post’, $post_id ) ) {
return $post_id;
}
}
/* OK, it’s safe for us to save the data now. */
// Sanitize the user input.
$mydata = sanitize_text_field( $_POST[‘myplugin_new_field’] );
// Update the meta field.
update_post_meta( $post_id, ‘_my_meta_value_key’, $mydata );
}
/**
* Render Meta Box content.
*
* @param WP_Post $post The post object.
*/
public function render_meta_box_content( $post ) {
// Add an nonce field so we can check for it later.
wp_nonce_field( ‘myplugin_inner_custom_box’, ‘myplugin_inner_custom_box_nonce’ );
// Use get_post_meta to retrieve an existing value from the database.
$value = get_post_meta( $post->ID, ‘_my_meta_value_key’, true );
// Display the form, using the current value.
?>
<label for=”myplugin_new_field”>
<?php _e( ‘Description for this field’, ‘textdomain’ ); ?>
</label>
<input type=”text” id=”myplugin_new_field” name=”myplugin_new_field” value=”<?php echo esc_attr( $value ); ?>” size=”25″ />
<?php
}
}
（德鲁·杰恩斯7年前贡献）
/**
* Register meta box(es).
*/
function wpdocs_register_meta_boxes() {
add_meta_box( ‘meta-box-id’, __( ‘My Meta Box’, ‘textdomain’ ), ‘wpdocs_my_display_callback’, ‘post’ );
}
add_action( ‘add_meta_boxes’, ‘wpdocs_register_meta_boxes’ );
/**
* Meta box display callback.
*
* @param WP_Post $post Current post object.
*/
function wpdocs_my_display_callback( $post ) {
// Display code/markup goes here. Don’t forget to include nonces!
}
/**
* Save meta box content.
*
* @param int $post_id Post ID
*/
function wpdocs_save_meta_box( $post_id ) {
// Save logic goes here. Don’t forget to include nonce checks!
}
add_action( ‘save_post’, ‘wpdocs_save_meta_box’ );
（由wpdevco在5年前贡献）
/**
* Register a meta box using a class.
*/
class WPDocs_Custom_Meta_Box {
/**
* Constructor.
*/
public function __construct() {
if ( is_admin() ) {
add_action( ‘load-post.php’, array( $this, ‘init_metabox’ ) );
add_action( ‘load-post-new.php’, array( $this, ‘init_metabox’ ) );
}
}
/**
* Meta box initialization.
*/
public function init_metabox() {
add_action( ‘add_meta_boxes’, array( $this, ‘add_metabox’ ) );
add_action( ‘save_post’, array( $this, ‘save_metabox’ ), 10, 2 );
}
/**
* Adds the meta box.
*/
public function add_metabox() {
add_meta_box(
‘my-meta-box’,
__( ‘My Meta Box’, ‘textdomain’ ),
array( $this, ‘render_metabox’ ),
‘post’,
‘advanced’,
‘default’
);
}
/**
* Renders the meta box.
*/
public function render_metabox( $post ) {
// Add nonce for security and authentication.
wp_nonce_field( ‘custom_nonce_action’, ‘custom_nonce’ );
}
/**
* Handles saving the meta box.
*
* @param int $post_id Post ID.
* @param WP_Post $post Post object.
* @return null
*/
public function save_metabox( $post_id, $post ) {
// Add nonce for security and authentication.
$nonce_name = isset( $_POST[‘custom_nonce’] ) ? $_POST[‘custom_nonce’] : ”;
$nonce_action = ‘custom_nonce_action’;
// Check if nonce is valid.
if ( ! wp_verify_nonce( $nonce_name, $nonce_action ) ) {
return;
}
// Check if user has permissions to save data.
if ( ! current_user_can( ‘edit_post’, $post_id ) ) {
return;
}
// Check if not an autosave.
if ( wp_is_post_autosave( $post_id ) ) {
return;
}
// Check if not a revision.
if ( wp_is_post_revision( $post_id ) ) {
return;
}
}
}
new WPDocs_Custom_Meta_Box();
（由Codex – 6年前贡献）
回调参数
$callback_args数组将作为第二个参数传递给回调函数。第一个参数是post的$post对象。
/**
* This function adds a meta box with a callback function of my_metabox_callback()
*/
function add_wpdocs_meta_box() {
$var1 = ‘this’;
$var2 = ‘that’;
add_meta_box(
‘metabox_id’,
__( ‘Metabox Title’, ‘textdomain’ ),
‘wpdocs_metabox_callback’,
‘page’,
‘normal’,
‘low’,
array( ‘foo’ => $var1, ‘bar’ => $var2 )
);
}
/**
* Get post meta in a callback
*
* @param WP_Post $post The current post.
* @param array $metabox With metabox id, title, callback, and args elements.
*/
function wpdocs_metabox_callback( $post, $metabox ) {
// Output last time the post was modified.
echo ‘Last Modified: ‘ . $post->post_modified;
// Output ‘this’.
echo $metabox[‘args’][‘foo’];
// Output ‘that’.
echo $metabox[‘args’][‘bar’];
// Output value of custom field.
echo get_post_meta( $post->ID, ‘wpdocs_custom_field’, true );
}
（由obiPlabon贡献- 5年前）
这是注册菜单屏幕metabox的方法:)
function op_register_menu_meta_box() {
add_meta_box(
‘op-menu-meta-box-id’,
esc_html__( ‘Op Menu MetaBox Title’, ‘text-domain’ ),
‘op_render_menu_meta_box’,
‘nav-menus’,
‘side’,
‘core’
);
}
add_action( ‘load-nav-menus.php’, ‘op_register_menu_meta_box’ );
function op_render_menu_meta_box() {
// Metabox content
echo ‘<strong>Hi, I am MetaBox.</strong>’;
}
（2年前由yitwaail提供）
在我看来，这个页面应该引用$callback_args的` __block_editor_compatible_meta_box `和` __back_compat_meta_box `选项，如本文所述:https://make.wordpress.org/core/2018/11/07/meta-box-compatibility-flags/
（由大卫贡献- 5年前）
一个经常被遗忘但也非常重要的事实是，任何save_post处理程序都应该检查多站点切换上下文。这里有一个这样的守卫的例子:
<?php
namespace DevWpNoteMetaBox;
add_action( ‘save_post’, __NAMESPACE_ . ‘save_fields’, 10, 3 );
function save_fields( $post_id, WP_Post $post, $update ) {
// check nonce …
// check autosave …
// check user capabilities …
// check if there was a multisite switch before
if ( is_multisite() && ms_is_switched() ) {
return $post_id;
}
// handle your meta box input …
}
这确保了与其他使用switch_to_blog()的插件在处理save_post钩子时的兼容性。如果他们在其他站点上再次调用wp_insert_post()，您的代码将覆盖错误的内容而不进行此检查。
（由Rubel Miah于4年前贡献）
//Register Meta Box
function rm_register_meta_box() {
add_meta_box( ‘rm-meta-box-id’, esc_html__( ‘RM MetaBox Title’, ‘text-domain’ ), ‘rm_meta_box_callback’, ‘post’, ‘advanced’, ‘high’ );
}
add_action( ‘add_meta_boxes’, ‘rm_register_meta_box’);
//Add field
function rm_meta_box_callback( $meta_id ) {
$outline = ‘<label for=”title_field” style=”width:150px; display:inline-block;”>’. esc_html__(‘Title Field’, ‘text-domain’) .'</label>’;
$title_field = get_post_meta( $meta_id->ID, ‘title_field’, true );
$outline .= ‘<input type=”text” name=”title_field” id=”title_field” class=”title_field” value=”‘. esc_attr($title_field) .’” style=”width:300px;”/>’;
echo $outline;
}
（由Md.Mehedi Hasan贡献- 1年前）
例子:
//Register Meta box
add_action(‘add_meta_boxes’,function (){
add_meta_box(‘csm-id’,’Social link’,’cm_field_cb’,’post’,’side’);
});
//Meta callback function
function cm_field_cb($post){
$cs_meta_val=get_post_meta($post->ID);
?>
<input type=”url” name=”cs-meta-name”
value=”<?php if( isset ( $cs_meta_val[‘cs-meta-name’])) echo $cs_meta_val[‘cs-meta-name’][0] ?>” >
<?php
}
//save meta value with save post hook
add_action(‘save_post’,function($post_id){
if(isset($_POST[‘cs-meta-name’])){
update_post_meta($post_id,’cs-meta-name’,$_POST[‘cs-meta-name’]);
}
});
// show meta value after post content
add_filter(‘the_content’,function($content){
$meta_val=get_post_meta(get_the_ID(),’cs-meta-name’,true);
return $cotent.$meta_val;
});
（由Kuba Mikita于4年前贡献）
这就是在save_post操作中处理metabox数据的方式。
function save_metabox_callback( $post_id ) {
if ( ! isset( $_POST[‘nonce’] ) ) {
return;
}
if ( ! wp_verify_nonce( $_POST[‘nonce’], ‘nonce_value’ ) ) {
return;
}
if ( defined( ‘DOING_AUTOSAVE’ ) && DOING_AUTOSAVE ) {
return;
}
if ( ! current_user_can( ‘edit_post’, $post_id ) ) {
return;
}
if ( isset( $_POST[‘post_type’] ) && ‘page’ === $_POST[‘post_type’] ) {
// do stuff
}
// Check if $_POST field(s) are available
// Sanitize
// Save
}
add_action( ‘save_post’, ‘save_metabox_callback’ );
（由Vincent Dubroeucq贡献- 1年前）
在metabox上的评论有轻微的缺陷
如果您需要向注释编辑屏幕添加一个metabox，您必须为$context参数传入值’ normal ‘。
// This will NOT work
add_meta_box(
‘my_comment_metabox_1’, // ID
__(‘My comment metabox 1’ ), // Title
‘prefix_comment_metabox’, // Callback
‘comment’ // Screen
);
// This WILL work. Same call, but with ‘normal’ for context instead of default ‘advanced’
add_meta_box(
‘my_comment_metabox_2’, // ID
__(‘My comment metabox 2’ ), // Title
‘prefix_comment_metabox’, // Callback
‘comment’, // Screen
‘normal’ // Context
);
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