Copyright (c) 2007 Tristan Rivoallan
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sfPropelActAsNestedSetBehaviorPlugin plugin
The sfPropelActAsNestedSetBehaviorPlugin is a symfony plugin that provides nested set capabilities to Propel objects.
Nested sets (aka modified preorder tree traversal) is a very efficient way (in terms of performances) to browse and edit a tree like structure in an RDBMS.
You can read a good introduction to nested sets on MySQL developers' zone.
Features
- Fully unit tested
- Possibility to store multiple trees in the same table
- Atomic operations
Installation
Install the plugin
symfony plugin-install http://plugins.symfony-project.com/sfPropelActAsNestedSetBehaviorPlugin
Enable Propel behavior support in propel.ini:
propel.builder.AddBehaviors = true
If you have to enable the behavior support, rebuild your model:
symfony propel-build-model
Enable the behavior for one of your Propel model:
// lib/model/ForumPost.php
class ForumPost
{
}
$columns_map = array('left' => ForumPost::TREE_LEFT,
'right' => ForumPost::TREE_RIGHT,
'parent' => ForumPost::TREE_PARENT,
'scope' => ForumPost::TOPIC_ID);
sfPropelBehavior::add('ForumPost', array('actasnestedset' => array('columns' => $columns_map)));
The column map is used by the behavior to know which columns hold information it needs :
- left : Model column holding nested set left value for a row
- right : Model column holding nested set right value for a row
- parent : Model column holding row's parent id (this is necessary because we use adjacency list tree traversal for some methods)
- scope : Model column holding row's scope id. The scope is used to differenciate trees stored in the same table
Usage
Simple tree creation :
$root = new ForumPost();
$root->makeRoot();
$root->save();
$p1 = new ForumPost();
$p1->insertAsFirstChildOf($root);
$p1->save();
$p2 = new ForumPost();
$p2->insertAsFirstChildOf($p1);
$p2->save();
/*
* Resulting tree :
*
* ROOT
* |- P1
* |- P2
*/
Multiple trees in a single table :
$root1 = new ForumPost();
$root1->makeRoot();
$root1->setTopicId(1);
$root1->save();
$root2 = new ForumPost();
$root2->makeRoot();
$root2->setTopicId(2);
$root2->save();
$p1 = new ForumPost();
$p1->insertAsFirstChildOf($root1);
$p1->save();
$p2 = new ForumPost();
$p2->insertAsFirstChildOf($root2);
$p2->save();
/*
* Resulting trees :
*
* ROOT1
* |- P1
*
* ROOT2
* |- P2
*/
Public API
Enabling the behaviors adds the following method to the Propel objects :
Insertion methods
void insertAsFirstChildOf(BaseObject $dest_node) : Inserts node as first child of given node.void insertAsLastChildOf(BaseObject $dest_node) : Inserts node as last child of given node.void insertAsNextSiblingOf(BaseObject $dest_node) : Inserts node as next sibling of given node.void insertAsPrevSiblingOf(BaseObject $dest_node) : Inserts node as previous sibling of given node.
Informational methods
bool hasChildren() : Returns true if given node as one or several children.bool isRoot() : Returns true if given node is a root node.bool hasParent() : Returns true if given node has a parent node.bool hasNextSibling() : Returns true if given node has a next sibling.bool hasPrevSibling() : Returns true if given node has a previous sibling.bool isLeaf() : Returns true if given node does not have children.integer getNumberOfChildren() : Returns given node number of direct children.integer getNumberOfDescendants() : Returns given node number of descendants (n level).integer getLevel() : Returns given node level.
Node retrieval methods
array getChildren($peer_method = 'doSelect') : Returns given node direct children.array getDescendants($peer_method = 'doSelect') : Returns given node descendants (n level).BaseObject retrieveNextSibling() : Returns given node next sibling.BaseObject retrievePrevSibling() : Returns given node previous sibling.BaseObject retrieveFirstChild() : NOT IMPLEMENTED YETBaseObject retrieveLastChild() : NOT IMPLEMENTED YETarray getPath() : NOT IMPLEMENTED YET
Tree modification methods
void moveToFirstChildOf(BaseObject $dest_node) : Moves node to first child of given node.void moveToLastChildOf(BaseObject $dest_node) : Moves node to last child of given node.void moveToNextSiblingOf() : NOT IMPLEMENTED YETvoid moveToPrevSiblingOf() : NOT IMPLEMENTED YETvoid deleteChildren() : NOT IMPLEMENTED YETvoid deleteTree() : NOT IMPLEMENTED YET
Helper methods
void makeRoot() : Sets node properties to make it a root node.BaseObject reload() : Returns an up to date version of node
Tristan Rivoallan 
