请帮帮我。我想在元框中显示用户的显示名称作为复选框。然后，我可以通过以下方式选择许多用户在帖子中显示一些内容：
if (in_array(\'special userID\', get_post_meta($post->ID, \'U_S_C_users\', true)) == true) {
// Show the content here
echo "ok";
}
根据我的代码，我看到以下错误：
warning: in_array() expects parameter 2 to be array in string:::: if (in_array($user->ID,$savedusers)){
我的代码：
<?php
/* Define the custom box */
add_action(\'add_meta_boxes\', \'User_specific_content_box\');
/* Adds a box to the main column on the custom post type edit screens */
function User_specific_content_box() {
add_meta_box(\'User_specific_content\', __( \'User specific content box\'),\'User_specific_content_box_inner\',\'class\');
}
/* Prints the box content */
function User_specific_content_box_inner() {
global $post,$wp_roles;
$savedusers = get_post_meta($post->ID, \'U_S_C_users\',true);
var_dump($savedusers);
// Use nonce for verification
wp_nonce_field( plugin_basename(__FILE__), \'User_specific_content_box_inner\' );
echo \'<h4>\'.__(\'By User Name:\').\'</h4>\';
$blogusers = get_users(\'blog_id=1&orderby=nicename\');
$usercount = 0;
foreach ($blogusers as $user) {
echo \'<input type="checkbox" name="U_S_C_users" value="\'.$user->ID.\'"\';
if (in_array($user->ID,$savedusers)){
echo \' checked\';
}
echo \'>\'.$user->display_name.\' \';
$usercount = $usercount + 1;
if ($usercount > 5){
echo \'<br/>\';
$usercount = 0;
}
}
}
/* Save Meta Box */
add_action(\'save_post\', \'User_specific_content_box_inner_save\');
/* When the post is saved, saves our custom data */
function User_specific_content_box_inner_save( $post_id ) {
global $post;
// verify this came from the our screen and with proper authorization,
// because save_post can be triggered at other times
if ( !wp_verify_nonce( $_POST[\'User_specific_content_box_inner\'], plugin_basename(__FILE__) ) )
return $post_id;
// verify if this is an auto save routine.
// If it is our form has not been submitted, so we dont want to do anything
if ( defined(\'DOING_AUTOSAVE\') && DOING_AUTOSAVE )
return $post_id;
// OK, we\'re authenticated: we need to find and save the data
$savedusers = get_post_meta($post_id, \'U_S_C_users\',true);
if (isset($_POST[\'U_S_C_users\']) && !empty($_POST[\'U_S_C_users\'])){
foreach ($_POST[\'U_S_C_users\'] as $u){
$new_users[] = $u;
}
update_post_meta($post_id, \'U_S_C_users\', $new_users);
}else{
if (count($savedusers) > 0){
delete_post_meta($post_id, \'U_S_C_users\');
}
}
}
?>
我的问题：
1- i see that error
2- i want to show just users with author role.
谢谢你的帮助
最合适的回答,由SO网友:Sally CJ 整理而成
发生该错误的原因是$savedusers 不是数组&mdash；in_array() 要求second参数是有效数组，如果不是，则引发错误（或警告）。
一个简单的解决方法是将变量类型转换为如下数组：
$savedusers = (array) get_post_meta( $post_id, \'U_S_C_users\', true );
或者更好，使用
wp_parse_id_list() 这确保了
$savedusers 是（用户）ID的数组：
$savedusers = wp_parse_id_list( get_post_meta( $post->ID, \'U_S_C_users\', true ) );
（您将在
User_specific_content_box_inner() 和
User_specific_content_box_inner_save() 哪里
get_post_meta() 已调用。）
其次，复选框应通过附加[] 给他们name 像这样：
echo \'<input type="checkbox" name="U_S_C_users[]" value="\'.$user->ID.\'"\';
