Pagelayout hooks: one place at the end of every page for extensions #

Since 6.0.15 every pagelayout ends with one line that includes design:pagelayout/hooks/body_end.tpl, and that template includes each template an extension lists in site.ini [PageLayoutHooks] BodyEnd[]. An extension that needs something on every page of every design (the website sidebar expwt is the first) adds one setting instead of asking every design to change its pagelayout.

The line in a pagelayout #

One line per template engine, just before </body>:

The kernel's designs carry it: standard, base, plain, mysite, admin, admin3, admin4 and admin4l. A design of an extension adds the line to its own pagelayouts. Without an entry in BodyEnd[] the hook prints nothing, so the line costs nothing on a site that does not use it.

Adding a hook #

In the extension's settings/site.ini.append.php:

[PageLayoutHooks]
BodyEnd[]=myext/body_end.tpl

myext/body_end.tpl is a template of the extension's design (design/standard/templates/myext/body_end.tpl), found through the design chain like any other.

What a hook may print #

A pagelayout that keeps the whole page in one cache block (the media designs do) renders the hook inside it, and the full-page cache keeps the page for everybody with the same roles. So a hook prints only what those keys cover: the siteaccess, the node, whether the visitor is signed in, and the roles. Whatever belongs to the user themselves (a name, a token, a preference) is fetched by the hook's script after the page has loaded. A hook that has nothing to show prints nothing: not even a comment.

expwt, for example, prints one custom element and one deferred script for a user with the policy expwt/use, and nothing for a visitor who is not signed in while its ShowToAnonymous is off (the website sidebar).