WordPress后台开发，无插件增加一键复制文章页面功能

这次要实现的功能是在 WordPress 后台的文章列表中，添加一键复制文章的按钮。完整地复制一篇文章，除了要复制文章内容外，还要复制文章所有的分类信息和关联字段，这是复制功能的核心。另外要实现这个功能还要带上一些后台的交互，为了避免不小心点到这个按钮徒增不必要的数据，还需要做个二次确认框，效果是这样的。

先要通过 post_row_actions 钩子增加一个”Duplicate”按钮（其实是个链接）

function brain1981_duplicate_post_link( $actions, $post ) {
if (current_user_can('edit_posts')) {
$actions['duplicate'] = '<a href="###" data-url="'. wp_nonce_url('admin.php?action=brain1981_duplicate_post&post=' . $post->ID, basename(__FILE__), 'duplicate_nonce' ) . '" title="Duplicate it" rel="permalink" class="duplicate-trigger">Duplicate</a>';
}
return $actions;
}
add_filter('post_row_actions', 'brain1981_duplicate_post_link', 30, 2 );

点击这个按钮弹出确认框，用 JS 实现，代码通过 admin_footer 钩子插入。

function brain1981_add_duplicate_script() {
$screen = get_current_screen();
$parent_base = $screen->parent_base;
if ( $parent_base=='edit' ) {
echo '<script>jQuery(function(){jQuery(".duplicate-trigger").on("click",function(){ var url=jQuery(this).data("url"); if(window.confirm("duplicate it?")) location.href=url; })})</script>';
}
}
add_filter('admin_footer', 'brain1981_add_duplicate_script');

接下来就是核心，复制文章和所有的字段、分类信息

function brain1981_duplicate_post(){
global $wpdb;
if ( !( isset($_REQUEST['post']) && isset($_REQUEST['action']) && $_REQUEST['action']=='brain1981_duplicate_post' ) ) {
wp_die('Error!');
}
//secure check
if ( !isset( $_GET['duplicate_nonce'] ) || !wp_verify_nonce( $_GET['duplicate_nonce'], basename( __FILE__ ) ) )
return;
//需要复制的文章
$post_id = absint( $_REQUEST['post'] );
$post = get_post( $post_id );
//指派作者为当前复制者
$current_user = wp_get_current_user();
$post_author = $current_user->ID;
//不改变作者
$post_author=$post->post_author;
if (isset( $post ) && $post != null) {
//建立文章数据
$args = array(
'ping_status' => $post->ping_status,
'post_author' => $post_author,
'post_content' => $post->post_content,
'post_excerpt' => $post->post_excerpt,
'post_name' => $post->post_name,
'post_parent' => $post->post_parent,
'post_password' => $post->post_password,
'post_title' => $post->post_title,
'post_type' => $post->post_type,
'to_ping' => $post->to_ping,
'menu_order' => $post->menu_order,
'comment_status' => $post->comment_status,
'post_status' => 'draft'
);
//建立文章
$new_post_id = wp_insert_post( $args );
//复制文章分类数据
$taxonomyArr = get_object_taxonomies($post->post_type);
foreach ($taxonomyArr as $taxonomy) {
$post_terms = wp_get_object_terms($post_id, $taxonomy, array('fields' => 'slugs'));
wp_set_object_terms($new_post_id, $post_terms, $taxonomy, false);
}
//SQL查询复制文章自定义字段CPM
$post_meta_data = $wpdb->get_results("SELECT meta_key, meta_value FROM $wpdb->postmeta WHERE post_id=$post_id");
if (count($post_meta_data)!=0) {
$sql_query = "INSERT INTO $wpdb->postmeta (post_id, meta_key, meta_value) ";
foreach ($post_meta_data as $meta_info) {
$meta_key = $meta_info->meta_key;
if( $meta_key == '_wp_old_slug' ) continue;
$meta_value = addslashes($meta_info->meta_value);
$sql_query_sel[]= "SELECT $new_post_id, '$meta_key', '$meta_value'";
}
$sql_query.= implode(" UNION ALL ", $sql_query_sel);
$wpdb->query($sql_query);
}
//如果有必要，可在复制完成后直接跳转到新的post编辑页面
wp_redirect( admin_url( 'post.php?action=edit&post=' . $new_post_id ) );
exit;
} else {
wp_die('Can not find the original post: ' . $post_id);
}
}
add_action( 'admin_action_brain1981_duplicate_post', 'brain1981_duplicate_post' );