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// Duplicate post as a draft and redirect to the edit post screen

function duplicate_post_as_draft(){
	global $wpdb;
	if (! ( isset( $_GET['post']) || isset( $_POST['post'])  || ( isset($_REQUEST['action']) && 'duplicate_post_as_draft' == $_REQUEST['action'] ) ) ) {
	\!h   wp_die('No post to duplicate has been supplied!');   //Optional: Error message can be changed
	}
 
	//get the original post id
	$post_id = (isset($_GET['post']) ? absint( $_GET['post'] ) : absint( $_POST['post'] ) );
	
	//and all the original post data then
	$post = get_post( $post_id );
 
	//if you don't want current user to be the new post author, then change next couple of lines to this: $new_post_author = $post->post_author;
	\!h $current_user = wp_get_current_user();
	\!h $new_post_author = $current_user->ID;
 
	
	//if post data exists, create the post duplicate
	if (isset( $post ) && $post != null) {
 
		//new post data array
	
		$args = array(
			'comment_status' => $post->comment_status,
			'ping_status'    => $post->ping_status,
			'post_author'    => $new_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_status'    => 'draft',
			'post_title'     => $post->post_title,
			'post_type'      => $post->post_type,
			'to_ping'        => $post->to_ping,
			'menu_order'     => $post->menu_order
		);
 
		//insert the post by wp_insert_post() function
		$new_post_id = wp_insert_post( $args );
 
		//get all current post terms ad set them to the new post draft
		$taxonomies = get_object_taxonomies($post->post_type); // returns array of taxonomy names for post type, ex array("category", "post_tag");
		foreach ($taxonomies 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);
		}
 
		//duplicate all post meta just in two SQL queries
		$post_meta_infos = $wpdb->get_results("SELECT meta_key, meta_value FROM $wpdb->postmeta WHERE post_id=$post_id");
		if (count($post_meta_infos)!=0) {
			$sql_query = "INSERT INTO $wpdb->postmeta (post_id, meta_key, meta_value) ";
			foreach ($post_meta_infos as $meta_info) {
				$meta_key = $meta_info->meta_key;
				$meta_value = addslashes($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);
		}
 
	//finally, redirect to the edit post screen for the new draft. Remove this if you want to stay on the main post page
	wp_redirect( admin_url( 'post.php?action=edit&post=' . $new_post_id ) );
		exit;
	} else {
	\!h     wp_die('Post creation failed, could not find original post: ' . $post_id);  //Optional: Error message can be changed
	}
}
add_action( 'admin_action_duplicate_post_as_draft', 'duplicate_post_as_draft' );
 
 //Add the duplicate link to action list for post_row_actions
	function rd_duplicate_post_link( $actions, $post ) {
		if (current_user_can('edit_posts')) {
		\!h   $actions['duplicate'] = '<a href="admin.php?action=duplicate_post_as_draft&amp;post=' . $post->ID . '" title="Duplicate this item" rel="permalink">Duplicate</a>'; //change button text here
		}
		return $actions;
	}
 
add_filter( 'post_row_actions', 'rd_duplicate_post_link', 10, 2 );