= sfPropelActAsNestedSetBehaviorPlugin plugin =

[[PageOutline]]

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 [http://dev.mysql.com/tech-resources/articles/hierarchical-data.html 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
 * Also maintains adjacency list properties, making your classes compatible with code based on this tree traversal methodology

== Installation ==

  * Install the plugin
  
    {{{
      symfony plugin-install http://plugins.symfony-project.com/sfPropelActAsNestedSetBehaviorPlugin
    }}}

  * Add new fields to your schema.xml
    
   {{{
    <column name="tree_left" type="INTEGER" required="true" /> 
    <column name="tree_right" type="INTEGER" required="true" /> 
    <column name="tree_parent" type="INTEGER" required="true" /> 
    <column name="topic_id" type="INTEGER" required="true" /> 
   }}}

  * 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'   => ForumPostPeer::TREE_LEFT,
                           'right'  => ForumPostPeer::TREE_RIGHT,
                           'parent' => ForumPostPeer::TREE_PARENT,
                           'scope'  => ForumPostPeer::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 ===

{{{
#!php
  $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 ===

{{{
#!php
  $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
   */
}}}

=== Lame threaded forum posts list example ===

{{{
  $root = ForumPostPeer::retrieveByPk(rootnodepk);
  <ul>
    <?php echo $root->getTitle() ?>

    <?php foreach ($root->getDescendants() as $post): ?>

       <li style="padding-left: <?php echo $post->getLevel() ?>em;">
            <?php echo $post->getTitle() ?>
       </li>

    <?php endforeach; ?>
  </ul>
}}}

=== Using nested sets and sfPropelPager ===

{{{
  // Decide which posts to fetch
  $c = new Criteria();
  $c->add(ForumPostPeer::TOPIC_ID, $topic_id);
  $c->addAscendingOrderByColumn(ForumPostPeer::TREE_LEFT); // ForumPostPeer::TREE_LEFT is the column holding nested set's left value
    
  // Create pager
  $pager = new sfPropelPager('ForumPost', 10);
  $pager->setCriteria($c);
  $pager->setPage($this->getRequestParameter('page', 1));
  $pager->init();
}}}

== 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()}}} : Returns given node first child.
 * {{{BaseObject retrieveLastChild()}}} : Returns given node last child.
 * {{{BaseObject retrieveParent()}}} : Returns given node parent.
 * {{{array getPath()}}} : Returns path to a specific node as an array, useful to create breadcrumbs.

=== 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 YET'''
 * {{{void moveToPrevSiblingOf()}}} : '''NOT IMPLEMENTED YET'''
 * {{{void deleteChildren()}}} : '''NOT IMPLEMENTED YET'''
 * {{{void 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

== Changelog ==

=== 2007-02-19 | 0.6.2 ===

 * Fixed a bug due to wrong usage of `rtrim`. (Thanks to Krešo Kunjas)

=== 2007-02-15 | 0.6.1 ===

Fixed minor bug in getPath()

=== 2007-02-15 | 0.6.0 ===

Implemented missing node retrieval methods : 

 * retrieveFirstChild
 * retrieveLastChild
 * retrieveParent
 * getPath
 
Updated docs and unit tests accordingly

=== 2007-02-14 | 0.5.1 ===

Pear package missed plugin's config.php file.

=== 2007-02-14 | 0.5.0 ===

Initial public release. The behavior is stable and fully unit-tested, but the API is not yet complete. Missing methods :

 * retrieveFirstChild
 * retrieveLastChild   
 * moveToPrevSiblingOf
 * moveToNextSiblingOf
 * deleteChildren
 * deleteTree
 * getPath