class Place_Model extends MPTT {

    protected $left_column     =    'lft'; //database column where left values are stored
	
    protected $right_column    =    'rgt';//database colunn where right values are stored
	
    protected $parent_column   =    'parent_id';//database column where parent ids are stored
	
    protected $scope_column    =    'scope';//database column where the scope is stored
    
    function __construct($id = FALSE)
    {
        parent::__construct($id);
    }
}

The name of the model uses the ORM conventions of Kohana. {singular_of_table}Model extends MPTT/

Make sure the 4 columns listed above are present in the table.

The values above are also the default values, if these are your values you do not need to supply them in the model.

Other notes

A node of whom its children are retrieved stores these children in ->children These children store their parent in ->parent

//Earth root node has id#1
$earth=new Place_Model(1);

$earth->get_children();
foreach($earth->children as $child)
{
echo $child->name;
echo $child->parent->name;
}

Retrieving a node

You can retrieve a single node by supplying its id to the constructor

$earth=new Place_Model(1);

But also by other ORM methods. I have not tested the overloading of where_key(), this thus might not work at all times.

Documentation

As an example I will work with a table called 'places'. The root node is 'Earth', its children something like 'North-America','Europe','Asia', children of Europe 'UK','Germany','France', children of France might be 'Paris','Bordeaux','Lyon' etc. This is what roughly will be used.

Creating the tree

make_root()

To create a tree you have to create a root node.

$root=new Place_Model();
$root->name='Earth';
$root->make_root();

Scope defaults to 1, with only 1 tree there's no need set it manually.

Inserting childs

   Earth
Asia Europe

Say you want to insert a child named North-America, its place can be left of Asia, right of Asia or right of Europe.

insert_as_first_child_of()

//Earth root node has id#1
$earth=new Place_Model(1);

$na=new Place_Model();
$na->name='North-America';
$na->insert_as_first_child_of($earth);

Inserts the child before Asia

insert_as_last_child_of()

//Earth root node has id#1
$earth=new Place_Model(1);

$na=new Place_Model();
$na->name='North-America';
$na->insert_as_last_child_of($earth);

Inserts the child after Asia

insert_as_next_sibling_of()

//Asia node has id#2
$asia=new Place_Model(2);

$na=new Place_Model();
$na->name='North-America';
$na->insert_as_next_sibling_of($asia);

Inserts the child to the right of Asia.

insert_as_prev_sibling_of()

See insert_next_sibling_of() but then it adds it to the right of Asia

Retrieval methods

get_children($return)

If $return is true it will return an array of the children of the current node. In either case the current node has a property ->children with the array of children. Each child also has the parent property with the parent object stored in it.

Earth has children Asia, Europe, North-America

//Earth root node has id#1
$earth=new Place_Model(1);

$earth->get_children();
foreach($earth->children as $child)
{
echo $child->name;
echo $child->parent->name;
}

$children=$earth->get_children(true);
foreach($children as $child)
{
echo $child->name;

}

$earth=new Place_Model();
$earth=$earth->get_root();

$earth->get_descendants();
//$earth now has the entire tree sored in it

get_first_child()

Returns first child of current node

get_last_child()

Returns last child of current node

get_prev_sibling()

Returns previous sibling of current node.

get_next_sibling

Returns next sibling of current node.

get_parent

Returns parent of current node.

get_tree($parent_node)

Returns object with tree. You can supply it with an id or a node object. Tree can be supplied to mptt->debug_tree();

Deleting methods

delete_tree()

Deletes an tree of the current scope, use with caution

delete_node($children)

Deletes current node and any children when $children is true. Default = true It will not delete the children when $children is false and will then move up the children in the hierarchy.

delete_descendants()

Deletes descendants of current node but not the node itself

delete_children()

Will just delete children of current node but not its descendants so descendants move up the tree.

Scope

The scope of an object will be retrieved from the record when the object is created.

get_scope()

Returns scope of current object

set_scope

Set scope of current object, only works on new objects.

//Asia node has id#2
$asia=new Place_Model(2);

$na=new Place_Model();
$na->set_scope(2);
$na->name='North-America';
$na->insert_as_next_sibling_of($asia);