nobrainer-tree

nobrainer-tree

A tree structure for NoBrainer documents using the materialized path pattern

Requirements

• nobrainer (~> 0.20.0)

Install

To install nobrainer-tree, simply add it to your Gemfile:

gem 'nobrainer-tree', :require => 'nobrainer/tree'

In order to get the latest development version of nobrainer-tree:

gem 'nobrainer-tree', :git => 'git://github.com/secondimpression/nobrainer-tree'

You might want to add :require => nil option and explicitly require 'nobrainer/tree' where needed and finally run

bundle install

Usage

Read the API documentation at https://github.com/secondimpression/nobrainer-tree and take a look at the NoBrainer::Tree module

class Node
  include NoBrainer::Document
  include NoBrainer::Tree
end

Utility methods

There are several utility methods that help getting to other related documents in the tree:

Node.root
Node.roots
Node.leaves

node.root
node.parent
node.children
node.ancestors
node.ancestors_and_self
node.descendants
node.descendants_and_self
node.siblings
node.siblings_and_self
node.leaves

In addition it's possible to check certain aspects of the document's position in the tree:

node.root?
node.leaf?
node.depth
node.ancestor_of?(other)
node.descendant_of?(other)
node.sibling_of?(other)

See NoBrainer::Tree for more information on these methods.

Ordering

NoBrainer::Tree doesn't order children by default. To enable ordering of tree nodes include the NoBrainer::Tree::Ordering module. This will add a position field to your document and provide additional utility methods:

node.lower_siblings
node.higher_siblings
node.first_sibling_in_list
node.last_sibling_in_list

node.move_up
node.move_down
node.move_to_top
node.move_to_bottom
node.move_above(other)
node.move_below(other)

node.at_top?
node.at_bottom?

Example:

class Node
  include NoBrainer::Document
  include NoBrainer::Tree
  include NoBrainer::Tree::Ordering
end

See NoBrainer::Tree::Ordering for more information on these methods.

Traversal

It's possible to traverse the tree using different traversal methods using the NoBrainer::Tree::Traversal module.

Example:

class Node
  include NoBrainer::Document
  include NoBrainer::Tree
  include NoBrainer::Tree::Traversal
end

node.traverse(:breadth_first) do |n|
  # Do something with Node n
end

Destroying

NoBrainer::Tree does not handle destroying of nodes by default. However it provides several strategies that help you to deal with children of deleted documents. You can simply add them as before_destroy callbacks.

Available strategies are:

• :nullify_children -- Sets the children's parent_id to null
• :move_children_to_parent -- Moves the children to the current document's parent
• :destroy_children -- Destroys all children by calling their #destroy method (invokes callbacks)
• :delete_descendants -- Deletes all descendants using a database query (doesn't invoke callbacks)

Example:

class Node
  include NoBrainer::Document
  include NoBrainer::Tree

  before_destroy :nullify_children
end

Callbacks

There are two callbacks that are called before and after the rearranging process. This enables you to do additional computations after the documents position in the tree is updated. See NoBrainer::Tree for details.

Example:

class Page
  include NoBrainer::Document
  include NoBrainer::Tree

  after_rearrange :rebuild_path

  field :slug
  field :path

  private

  def rebuild_path
    self.path = self.ancestors_and_self.collect(&:slug).join('/')
  end
end

Validations

NoBrainer::Tree currently does not validate the document's children or parent associations by default. To explicitly enable validation for children and parent documents it's required to add a validates_associated validation.

Example:

class Node
  include NoBrainer::Document
  include NoBrainer::Tree

  validates_associated :parent, :children
end

Build Status

nobrainer-tree is on Travis CI running the specs on Ruby Head, Ruby 1.9.3, Ruby 2.0 and Ruby 2.1

Known issues

See https://github.com/secondimpression/nobrainer-tree/issues

Repository

See https://github.com/secondimpression/nobrainer-tree and feel free to fork it!

Contributors

See a list of all contributors at https://github.com/benedikt/mongoid-tree/contributors and https://github.com/secondimpression/nobrainer-tree/contributors. Thanks a lot everyone!

Support

If you like nobrainer-tree and want to support the development, the original author would appreciate a small donation:

Copyright

Copyright (c) 2010-2013 Benedikt Deicke. See LICENSE for details.