我在 functions.php 有 2 種不同的作業方法用于后端。下面的每個方法都有 2 個鉤子；1 顯示新的自定義欄位和另一個掛鉤來保存\更新值：
方法一：
function media_hacks_attachment_field_to_edit( $form_fields, $post ){
// https://codex.wordpress.org/Function_Reference/wp_get_attachment_metadata
$media_author = get_post_meta( $post->ID, 'media_author', true );
$form_fields['media_author'] = array(
'value' => $media_author ? $media_author : '',
'label' => __( 'Author' )
);
return $form_fields;
}
add_filter( 'attachment_fields_to_edit', 'media_hacks_attachment_field_to_edit', null, 2 );
//Saving value on Update (method 1)
function media_hacks_edit_attachment( $attachment_id ){
if ( isset( $_REQUEST['attachments'][$attachment_id]['media_author'] ) ) {
$media_author = $_REQUEST['attachments'][$attachment_id]['media_author'];
update_post_meta( $attachment_id, 'media_author', $media_author );
}
}
add_action( 'edit_attachment', 'media_hacks_edit_attachment' );
方法二：
function my_image_attachment_fields_to_edit($form_fields, $post) {
// $form_fields is a special array of fields to include in the attachment form
// $post is the attachment record in the database
// $post->post_type == 'attachment'
// (attachments are treated as posts in Wordpress)
// add our custom field to the $form_fields array
// input type="text" name/id="attachments[$attachment->ID][custom1]"
$form_fields["custom1"] = array(
"label" => __("Custom Text Field"),
"input" => "text", // this is default if "input" is omitted
"value" => get_post_meta($post->ID, "_custom1", true)
);
// if you will be adding error messages for your field,
// then in order to not overwrite them, as they are pre-attached
// to this array, you would need to set the field up like this:
$form_fields["custom1"]["label"] = __("Custom Text Field");
$form_fields["custom1"]["input"] = "text";
$form_fields["custom1"]["value"] = get_post_meta($post->ID, "_custom1", true);
return $form_fields;
}
// attach our function to the correct hook
add_filter("attachment_fields_to_edit", "my_image_attachment_fields_to_edit", null, 2);
//Saving value on Update (method 2)
function my_image_attachment_fields_to_save($post, $attachment) {
// $attachment part of the form $_POST ($_POST[attachments][postID])
// $post attachments wp post array - will be saved after returned
// $post['post_type'] == 'attachment'
if( isset($attachment['custom1']) ){
// update_post_meta(postID, meta_key, meta_value);
update_post_meta($post['ID'], '_custom1', $attachment['custom1']);
}
return $post;
}
add_filter("attachment_fields_to_save", "my_image_attachment_fields_to_save", null, 2);
這是后端媒體庫（自定義文本欄位和作者）的良好結果：
這就是后端儀表板。
我的問題是前端：
現在如何在 FRONTEND 檢索和顯示這 2 個自定義欄位的值？
這是我在模板 php 頁面上的失敗嘗試：
<tr id='MySpecialRow'>
<td colspan='2' style='background:#000;color:#fff;'>
<?php
$args = array('cat' => 8);
$query = new WP_Query($args);
if ($query->have_posts()) {
// some code here if you want.
while ($query->have_posts()) {
$query->the_post();
$untitled_meta = rwmb_meta('image_advanced_8hswqfsoqai', '', get_the_ID());
foreach ($untitled_meta as $image) {
$media_author = get_post_meta( get_the_ID(), 'media_author', true );
echo get_the_ID();//correctly prints post id
echo $media_author;//prints nothing :(
}
}
}
?>
</td>
</tr>
小筆記：
get_the_ID()確實列印帖子ID，但$media_author沒有價值:(我正在執行 WordPress 帖子查詢回圈，因為包含自定義欄位的庫存在于帖子中。換句話說，我沒有帖子 ID，因為我在頁面模板中。
uj5u.com熱心網友回復：
您獲得的陣列將影像發布物件 ID 作為陣列鍵，因此您還需要使用擴展的 foreach 語法來訪問該鍵。
foreach ($untitled_meta as $id => $image) {
$media_author = get_post_meta( $id, 'media_author', true );
通常在遍歷陣列資料時，您很少需要訪問密鑰，但是當您這樣做時，PHP 也提供了$key => $value訪問密鑰的語法，https://www.php.net/manual/en/control -structures.foreach.php
轉載請註明出處，本文鏈接：https://www.uj5u.com/qukuanlian/487985.html