The persistent variable #

This page is for designers who need the content template to influence the frame: hide a side column on a landing page, add a body class for a class, change the page title. The view template runs before the pagelayout and cannot reach it directly; the persistent variable carries the message.

Contents #

1. Setting it
2. Reading it
3. Why "persistent"
4. Helpers
5. Examples in the shipped designs

Setting it #

In a full view (or an override of it), set the template variable persistent_variable to a hash in the root scope:

{set scope=global persistent_variable=hash( 'body_class', 'landing', 'left_menu', false() )}

The content view reads it after rendering (kernel/classes/eznodeviewfunctions.php: the kernel sets it to false before the view runs and copies any other value into content_info).

Reading it #

In the pagelayout:

{def $pv = cond( and( is_array( $module_result.content_info ), is_set( $module_result.content_info.persistent_variable ) ),
                 $module_result.content_info.persistent_variable, false() )}
<body class="{if and( $pv, is_set( $pv.body_class ) )}{$pv.body_class|wash}{/if}">

Why "persistent" #

The value is stored with the view cache entry (the kernel adds it to the cache keys), so a page served from the view cache delivers the same value as when it was rendered. A variable set any other way would be lost on a cache hit.

Helpers #

• ezcss_require and ezscript_require use the persistent variable to pass stylesheet and script lists.
• The ezwebin extension's ezpagedata_set( 'key', value ) and ezpagedata_append write into it, and ezpagedata() reads it back (The ezwebin design as a base).

Examples in the shipped designs #

admin4's pagelayout reads persistent_variable.left_menu and extra_menu, so an edit page template can ask for its own left column (design/admin4/templates/pagelayout.tpl).

Related pages #

• Module result and content info
• Full view
• Free documentation: this page is free to copy, translate and improve under the GNU FDL 1.3.