Objects, nodes and locations #

This page is for developers who come from systems where a page is its place in the menu. In Exponential the content and its place are two different things: the object holds the content, its nodes (locations) put it into the tree. Knowing which one you hold in a template or in PHP avoids most beginner mistakes.

Contents #

1. Object and node side by side
2. The main node and extra locations
3. The tree: paths, depth and the fixed tops
4. Sort order of children
5. Hidden and invisible
6. Moving, copying and removing
7. Which ID to use where
8. In templates and in PHP

Object and node side by side #

A page view on the site is always the view of a node: /content/view/full/<node id>, or the node's URL alias. The node gives you its object ($node.object), and the object gives you its nodes (assigned_nodes, main_node).

The main node and extra locations #

An object can be placed in several parts of the tree: a product under two categories, a person under the team page and the contact page. Each place is a node; one of them is the main node (main_node_id). Editors add locations on the object's Locations tab in the administration.

• All nodes show the same object, so an edit appears everywhere at once.
• The main node gives the canonical address. Link and set canonical URLs with the main node: $node.object.main_node.url_alias in a template (Nodes, objects and attributes).
• Fetches return nodes; a list that covers two locations of the same object returns it twice unless you pass main_node_only (Fetching content in templates).

Use extra locations where the content truly belongs in two places. For "related reading" boxes, use object relations instead (Relations and embeds).

The tree: paths, depth and the fixed tops #

Every node stores its path_string (the node IDs from the top, for example /1/2/61/74/) and its depth. These make subtree fetches and subtree permissions fast. The shipped tree has fixed tops, set in settings/content.ini [NodeSettings]:

A siteaccess can start its site lower in the tree, which is how several sites share one tree (Siteaccesses and multisite).

Sort order of children #

Each node stores how its children are sorted (sort_field, sort_order); new nodes take the default of their class. The sort fields are constants of eZContentObjectTreeNode (SORT_FIELD_PATH, PUBLISHED, MODIFIED, SECTION, DEPTH, CLASS_IDENTIFIER, CLASS_NAME, PRIORITY, NAME, MODIFIED_SUBNODE, NODE_ID, CONTENTOBJECT_ID, VISIBILITY). With priority sorting, editors set the order by hand in the sub-items list. In a template, $node.sort_array gives you the node's own order to pass to a fetch, so your menu follows what editors chose.

Hidden and invisible #

Visitors do not see invisible nodes while site.ini [SiteAccessSettings] ShowHiddenNodes=false, the shipped value; the administration siteaccess usually shows them. Hiding is not a permission: a hidden node is still readable by anyone with content/read on a siteaccess that shows hidden nodes. For real access control use sections and roles (Sections, roles and policies).

Moving, copying and removing #

• Move changes the parent of one node; the URL aliases of the subtree follow and the old addresses keep redirecting (URL aliases and routing).
• Copy creates a new object (with a new object ID) and a node for it; a subtree can be copied with bin/php/ezsubtreecopy.php.
• Remove a node: if the object has other locations, only this location goes. If it was the last one, the object goes to the trash by default and can be restored from there (Publishing, versions and the trash).

From PHP, use the kernel operations so caches, search and URL aliases follow: see Content from PHP.

Which ID to use where #

Find a node ID shows where to read IDs in the administration.

In templates and in PHP #

In a node view template the current node is $node:

<h1>{$node.name|wash()}</h1>
<p>Object {$node.contentobject_id}, node {$node.node_id}, depth {$node.depth}</p>
{if $node.object.assigned_nodes|count()|gt( 1 )}
    <link rel="canonical" href={$node.object.main_node.url_alias|ezurl( , 'full' )} />
{/if}

In PHP:

<?php
$node = eZContentObjectTreeNode::fetch( 2 );        // a node by node ID
$object = $node->object();                          // its object
$main = $object->mainNode();                        // the main node
$all = $object->assignedNodes();                    // every location
$byRemote = eZContentObject::fetchByRemoteID( 'expsite-about-page' );

eZContentObjectTreeNode and eZContentObject in the book list the methods.

Related pages #

• The content model
• Node attributes reference
• Mapping content: locations
• Free documentation: this page is free to copy, translate and improve under the GNU FDL 1.3.