111 lines
4.5 KiB
Ruby
111 lines
4.5 KiB
Ruby
module ActiveRecord
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module Acts
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module Tree
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def self.included(base)
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base.extend(ClassMethods)
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end
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# Specify this +acts_as+ extension if you want to model a tree structure by providing a parent association and a children
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# association. This requires that you have a foreign key column, which by default is called +parent_id+.
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#
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# class Category < ActiveRecord::Base
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# acts_as_tree :order => "name"
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# end
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#
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# Example:
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# root
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# \_ child1
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# \_ subchild1
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# \_ subchild2
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#
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# root = Category.create("name" => "root")
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# child1 = root.children.create("name" => "child1")
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# subchild1 = child1.children.create("name" => "subchild1")
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#
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# root.parent # => nil
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# child1.parent # => root
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# root.children # => [child1]
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# root.children.first.children.first # => subchild1
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#
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# In addition to the parent and children associations, the following instance methods are added to the class
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# after calling <tt>acts_as_tree</tt>:
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# * <tt>siblings</tt> - Returns all the children of the parent, excluding the current node (<tt>[subchild2]</tt> when called on <tt>subchild1</tt>)
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# * <tt>self_and_siblings</tt> - Returns all the children of the parent, including the current node (<tt>[subchild1, subchild2]</tt> when called on <tt>subchild1</tt>)
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# * <tt>ancestors</tt> - Returns all the ancestors of the current node (<tt>[child1, root]</tt> when called on <tt>subchild2</tt>)
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# * <tt>root</tt> - Returns the root of the current node (<tt>root</tt> when called on <tt>subchild2</tt>)
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module ClassMethods
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# Configuration options are:
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#
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# * <tt>foreign_key</tt> - specifies the column name to use for tracking of the tree (default: +parent_id+)
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# * <tt>order</tt> - makes it possible to sort the children according to this SQL snippet.
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# * <tt>counter_cache</tt> - keeps a count in a +children_count+ column if set to +true+ (default: +false+).
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def acts_as_tree(options = {})
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configuration = { :foreign_key => "parent_id", :dependent => :destroy, :order => nil, :counter_cache => nil }
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configuration.update(options) if options.is_a?(Hash)
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belongs_to :parent, :class_name => name, :foreign_key => configuration[:foreign_key], :counter_cache => configuration[:counter_cache]
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has_many :children, :class_name => name, :foreign_key => configuration[:foreign_key], :order => configuration[:order], :dependent => configuration[:dependent]
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class_eval <<-EOV
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include ActiveRecord::Acts::Tree::InstanceMethods
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def self.roots
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find(:all, :conditions => "#{configuration[:foreign_key]} IS NULL", :order => #{configuration[:order].nil? ? "nil" : %Q{"#{configuration[:order]}"}})
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end
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def self.root
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find(:first, :conditions => "#{configuration[:foreign_key]} IS NULL", :order => #{configuration[:order].nil? ? "nil" : %Q{"#{configuration[:order]}"}})
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end
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EOV
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end
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end
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module InstanceMethods
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# Returns list of ancestors, starting from parent until root.
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#
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# subchild1.ancestors # => [child1, root]
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def ancestors
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node, nodes = self, []
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nodes << node = node.parent while node.parent
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nodes
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end
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# Returns list of descendants.
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#
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# root.descendants # => [child1, subchild1, subchild2]
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def descendants
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children + children.collect(&:descendants).flatten
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end
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# Returns list of descendants and a reference to the current node.
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#
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# root.self_and_descendants # => [root, child1, subchild1, subchild2]
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def self_and_descendants
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[self] + descendants
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end
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# Returns the root node of the tree.
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def root
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node = self
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node = node.parent while node.parent
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node
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end
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# Returns all siblings of the current node.
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#
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# subchild1.siblings # => [subchild2]
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def siblings
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self_and_siblings - [self]
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end
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# Returns all siblings and a reference to the current node.
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#
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# subchild1.self_and_siblings # => [subchild1, subchild2]
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def self_and_siblings
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parent ? parent.children : self.class.roots
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end
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end
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end
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end
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end
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