Duplicate Page/Post Snippet

The snippet below adds duplicate option to edit menu for any page or post type.

Originally copied from WP Code Snippets Library and altered to clear the slug so it wont need to be edited every time.

Add this PHP snippet to WP Code Sippets and set to run in Admin Only.

// Add duplicate button to post/page list of actions.
add_filter( 'post_row_actions', 'wpcode_snippet_duplicate_post_link', 10, 2 );
add_filter( 'page_row_actions', 'wpcode_snippet_duplicate_post_link', 10, 2 );

// Let's make sure the function doesn't already exist.
if ( ! function_exists( 'wpcode_snippet_duplicate_post_link' ) ) {
	/**
	 * @param array   $actions The actions added as links to the admin.
	 * @param WP_Post $post The post object.
	 *
	 * @return array
	 */
	function wpcode_snippet_duplicate_post_link( $actions, $post ) {

		// Don't add action if the current user can't create posts of this post type.
		$post_type_object = get_post_type_object( $post->post_type );

		if ( null === $post_type_object || ! current_user_can( $post_type_object->cap->create_posts ) ) {
			return $actions;
		}


		$url = wp_nonce_url(
			add_query_arg(
				array(
					'action'  => 'wpcode_snippet_duplicate_post',
					'post_id' => $post->ID,
				),
				'admin.php'
			),
			'wpcode_duplicate_post_' . $post->ID,
			'wpcode_duplicate_nonce'
		);

		$actions['wpcode_duplicate'] = '<a href="' . $url . '" title="Duplicate item" rel="permalink">Duplicate</a>';

		return $actions;
	}
}

/**
 * Handle the custom action when clicking the button we added above.
 */
add_action( 'admin_action_wpcode_snippet_duplicate_post', function () {

	if ( empty( $_GET['post_id'] ) ) {
		wp_die( 'No post id set for the duplicate action.' );
	}

	$post_id = absint( $_GET['post_id'] );

	// Check the nonce specific to the post we are duplicating.
	if ( ! isset( $_GET['wpcode_duplicate_nonce'] ) || ! wp_verify_nonce( $_GET['wpcode_duplicate_nonce'], 'wpcode_duplicate_post_' . $post_id ) ) {
		// Display a message if the nonce is invalid, may it expired.
		wp_die( 'The link you followed has expired, please try again.' );
	}

	// Load the post we want to duplicate.
	$post = get_post( $post_id );

	// Create a new post data array from the post loaded.
	if ( $post ) {
		$current_user = wp_get_current_user();
		$new_post     = array(
			'comment_status' => $post->comment_status,
			'menu_order'     => $post->menu_order,
			'ping_status'    => $post->ping_status,
			'post_author'    => $current_user->ID,
			'post_content'   => $post->post_content,
			'post_excerpt'   => $post->post_excerpt,
			'post_name'      => '', // Clear the slug so WP generates a new one.
			'post_parent'    => $post->post_parent,
			'post_password'  => $post->post_password,
			'post_status'    => 'draft',
			'post_title'     => $post->post_title . ' (copy)',// Add "(copy)" to the title.
			'post_type'      => $post->post_type,
			'to_ping'        => $post->to_ping,
		);
		// Create the new post
		$duplicate_id = wp_insert_post( $new_post );
		// Copy the taxonomy terms.
		$taxonomies = get_object_taxonomies( get_post_type( $post ) );
		if ( $taxonomies ) {
			foreach ( $taxonomies as $taxonomy ) {
				$post_terms = wp_get_object_terms( $post_id, $taxonomy, array( 'fields' => 'slugs' ) );
				wp_set_object_terms( $duplicate_id, $post_terms, $taxonomy );
			}
		}
		// Copy all the custom fields.
		$post_meta = get_post_meta( $post_id );
		if ( $post_meta ) {

			foreach ( $post_meta as $meta_key => $meta_values ) {
				if ( '_wp_old_slug' === $meta_key ) { // skip old slug.
					continue;
				}
				foreach ( $meta_values as $meta_value ) {
					add_post_meta( $duplicate_id, $meta_key, $meta_value );
				}
			}
		}

		// Redirect to edit the new post.
		wp_safe_redirect(
			add_query_arg(
				array(
					'action' => 'edit',
					'post'   => $duplicate_id
				),
				admin_url( 'post.php' )
			)
		);
		exit;
	} else {
		wp_die( 'Error loading post for duplication, please try again.' );
	}
} );