Class: AkActsAsTree  - X-Ref

acts_as_tree

Makes your model acts as a tree (surprise!). Consider the following example:

class Category extends ActiveRecord {
var $acts_as = 'tree';
}

$Category = new Category;

$CategoryA = $Category->create();
$CategoryAa = $Category->create();
$CategoryAa1 = $Category->create();
$CategoryAa2 = $Category->create();
$CategoryAb = $Category->create();
$CategoryB = $Category->create();

$CategoryA->tree->addChild($CategoryAa)
$CategoryA->tree->addChild($CategoryAb)
$CategoryAa->tree->addChild($CategoryAa1)
$CategoryAa->tree->addChild($CategoryAa2)


This will effectively give you:

Category A
\_ Category Aa
\_ Category Aa1
\_ Category Aa2
\_ Category Ab
Category B


OK. Admittedly you won't get a graph in real life. But at least the following functions:

$CategoryA->tree->hasChildren()        # ==> true
$CategoryA->tree->childrenCount()    # ==> 2
$CategoryA->tree->getChildren()         # ==> array($CategoryAa, $CategoryAb)
// fairly expensive operation follows
// (yes, array(parent, array_of_children) is not nice but unfortunately PHP doesn't allow for objects as keys)
$CategoryA->tree->getDescendants()    # ==> array(array($CategoryAa, array($CategoryAa1, $CategoryAa2)), $CategoryAb)

$CategoryAa->tree->getChildren()        # ==> array($CategoryAa1, $CategoryAa2)
$CategoryAa->tree->getSiblings()        # ==> array($CategoryAb)
$CategoryAa->tree->hasParent()        # ==> true
$CategoryAa->tree->getParent()        # ==> $CategoryA

$CatagoryAa1->tree->hasChildren()    # ==> false
$CategoryAa1->tree->getParent()        # ==> $CategoryAa
// fairly expensive operation follows
$CategoryAa1->tree->getAncestors()    # ==> array($CategoryAa, $CategoryA)
// fairly expensive operation follows
$CategoryAa1->tree->getAncestors(1)    # ==> array($CategoryAa)


To make this work your model needs a parent_id column (whose name can be overriden with +parent_column+. Furthermore
you can set the +dependent+ option to automatically delete all children if their parent gets deleted. Otherwise they
will become orphants (i.e. have parent_id = NULL)

(Note that on adding a child it will be saved. If the parent has been unsaved until now it will also be saved.)