555 lines
21 KiB
Ruby
555 lines
21 KiB
Ruby
module CollectiveIdea #:nodoc:
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module Acts #:nodoc:
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module NestedSet #:nodoc:
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def self.included(base)
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base.extend(SingletonMethods)
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end
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# This acts provides Nested Set functionality. Nested Set is a smart way to implement
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# an _ordered_ tree, with the added feature that you can select the children and all of their
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# descendants with a single query. The drawback is that insertion or move need some complex
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# sql queries. But everything is done here by this module!
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#
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# Nested sets are appropriate each time you want either an orderd tree (menus,
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# commercial categories) or an efficient way of querying big trees (threaded posts).
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#
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# == API
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#
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# Methods names are aligned with acts_as_tree as much as possible, to make replacment from one
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# by another easier, except for the creation:
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#
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# in acts_as_tree:
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# item.children.create(:name => "child1")
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#
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# in acts_as_nested_set:
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# # adds a new item at the "end" of the tree, i.e. with child.left = max(tree.right)+1
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# child = MyClass.new(:name => "child1")
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# child.save
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# # now move the item to its right place
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# child.move_to_child_of my_item
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#
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# You can pass an id or an object to:
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# * <tt>#move_to_child_of</tt>
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# * <tt>#move_to_right_of</tt>
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# * <tt>#move_to_left_of</tt>
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#
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module SingletonMethods
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# Configuration options are:
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#
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# * +:parent_column+ - specifies the column name to use for keeping the position integer (default: parent_id)
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# * +:left_column+ - column name for left boundry data, default "lft"
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# * +:right_column+ - column name for right boundry data, default "rgt"
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# * +:scope+ - restricts what is to be considered a list. Given a symbol, it'll attach "_id"
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# (if it hasn't been already) and use that as the foreign key restriction. You
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# can also pass an array to scope by multiple attributes.
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# Example: <tt>acts_as_nested_set :scope => [:notable_id, :notable_type]</tt>
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# * +:dependent+ - behavior for cascading destroy. If set to :destroy, all the
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# child objects are destroyed alongside this object by calling their destroy
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# method. If set to :delete_all (default), all the child objects are deleted
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# without calling their destroy method.
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#
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# See CollectiveIdea::Acts::NestedSet::ClassMethods for a list of class methods and
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# CollectiveIdea::Acts::NestedSet::InstanceMethods for a list of instance methods added
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# to acts_as_nested_set models
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def acts_as_nested_set(options = {})
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options = {
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:parent_column => 'parent_id',
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:left_column => 'lft',
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:right_column => 'rgt',
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:order => 'id',
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:dependent => :delete_all, # or :destroy
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}.merge(options)
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if options[:scope].is_a?(Symbol) && options[:scope].to_s !~ /_id$/
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options[:scope] = "#{options[:scope]}_id".intern
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end
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write_inheritable_attribute :acts_as_nested_set_options, options
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class_inheritable_reader :acts_as_nested_set_options
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include Comparable
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include Columns
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include InstanceMethods
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extend Columns
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extend ClassMethods
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# no bulk assignment
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attr_protected left_column_name.intern,
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right_column_name.intern,
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parent_column_name.intern
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before_create :set_default_left_and_right
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before_destroy :prune_from_tree
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# no assignment to structure fields
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[left_column_name, right_column_name, parent_column_name].each do |column|
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module_eval <<-"end_eval", __FILE__, __LINE__
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def #{column}=(x)
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raise ActiveRecord::ActiveRecordError, "Unauthorized assignment to #{column}: it's an internal field handled by acts_as_nested_set code, use move_to_* methods instead."
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end
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end_eval
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end
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named_scope :roots, :conditions => {parent_column_name => nil}, :order => quoted_left_column_name
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named_scope :leaves, :conditions => "#{quoted_right_column_name} - #{quoted_left_column_name} = 1", :order => quoted_left_column_name
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if self.respond_to?(:define_callbacks)
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define_callbacks("before_move", "after_move")
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end
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end
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end
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module ClassMethods
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# Returns the first root
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def root
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roots.find(:first)
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end
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def valid?
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left_and_rights_valid? && no_duplicates_for_columns? && all_roots_valid?
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end
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def left_and_rights_valid?
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count(
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:joins => "LEFT OUTER JOIN #{quoted_table_name} AS parent ON " +
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"#{quoted_table_name}.#{quoted_parent_column_name} = parent.#{primary_key}",
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:conditions =>
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"#{quoted_table_name}.#{quoted_left_column_name} IS NULL OR " +
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"#{quoted_table_name}.#{quoted_right_column_name} IS NULL OR " +
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"#{quoted_table_name}.#{quoted_left_column_name} >= " +
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"#{quoted_table_name}.#{quoted_right_column_name} OR " +
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"(#{quoted_table_name}.#{quoted_parent_column_name} IS NOT NULL AND " +
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"(#{quoted_table_name}.#{quoted_left_column_name} <= parent.#{quoted_left_column_name} OR " +
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"#{quoted_table_name}.#{quoted_right_column_name} >= parent.#{quoted_right_column_name}))"
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) == 0
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end
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def no_duplicates_for_columns?
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scope_string = Array(acts_as_nested_set_options[:scope]).map do |c|
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connection.quote_column_name(c)
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end.push(nil).join(", ")
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[quoted_left_column_name, quoted_right_column_name].all? do |column|
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# No duplicates
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find(:first,
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:select => "#{scope_string}#{column}, COUNT(#{column})",
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:group => "#{scope_string}#{column}
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HAVING COUNT(#{column}) > 1").nil?
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end
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end
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# Wrapper for each_root_valid? that can deal with scope.
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def all_roots_valid?
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if acts_as_nested_set_options[:scope]
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roots(:group => scope_column_names).group_by{|record| scope_column_names.collect{|col| record.send(col.to_sym)}}.all? do |scope, grouped_roots|
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each_root_valid?(grouped_roots)
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end
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else
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each_root_valid?(roots)
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end
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end
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def each_root_valid?(roots_to_validate)
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left = right = 0
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roots_to_validate.all? do |root|
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(root.left > left && root.right > right).tap do
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left = root.left
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right = root.right
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end
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end
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end
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# Rebuilds the left & rights if unset or invalid. Also very useful for converting from acts_as_tree.
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def rebuild!(force=false)
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# Don't rebuild a valid tree.
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# valid? doesn't strictly validate the tree
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return true if !force && valid?
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scope = lambda{|node|}
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if acts_as_nested_set_options[:scope]
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scope = lambda{|node|
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scope_column_names.inject(""){|str, column_name|
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str << "AND #{connection.quote_column_name(column_name)} = #{connection.quote(node.send(column_name.to_sym))} "
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}
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}
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end
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indices = {}
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set_left_and_rights = lambda do |node|
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# set left
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node[left_column_name] = indices[scope.call(node)] += 1
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# find
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find(:all, :conditions => ["#{quoted_parent_column_name} = ? #{scope.call(node)}", node], :order => "#{quoted_left_column_name}, #{quoted_right_column_name}, #{acts_as_nested_set_options[:order]}").each{|n| set_left_and_rights.call(n) }
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# set right
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node[right_column_name] = indices[scope.call(node)] += 1
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node.save!
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end
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# Find root node(s)
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root_nodes = find(:all, :conditions => "#{quoted_parent_column_name} IS NULL", :order => "#{quoted_left_column_name}, #{quoted_right_column_name}, #{acts_as_nested_set_options[:order]}").each do |root_node|
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# setup index for this scope
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indices[scope.call(root_node)] ||= 0
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set_left_and_rights.call(root_node)
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end
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end
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end
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# Mixed into both classes and instances to provide easy access to the column names
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module Columns
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def left_column_name
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acts_as_nested_set_options[:left_column]
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end
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def right_column_name
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acts_as_nested_set_options[:right_column]
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end
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def parent_column_name
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acts_as_nested_set_options[:parent_column]
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end
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def scope_column_names
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Array(acts_as_nested_set_options[:scope])
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end
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def quoted_left_column_name
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connection.quote_column_name(left_column_name)
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end
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def quoted_right_column_name
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connection.quote_column_name(right_column_name)
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end
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def quoted_parent_column_name
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connection.quote_column_name(parent_column_name)
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end
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def quoted_scope_column_names
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scope_column_names.collect {|column_name| connection.quote_column_name(column_name) }
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end
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end
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# Any instance method that returns a collection makes use of Rails 2.1's named_scope (which is bundled for Rails 2.0), so it can be treated as a finder.
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#
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# category.self_and_descendants.count
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# category.ancestors.find(:all, :conditions => "name like '%foo%'")
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module InstanceMethods
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# Value of the parent column
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def parent_id
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self[parent_column_name]
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end
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# Value of the left column
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def left
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self[left_column_name]
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end
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# Value of the right column
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def right
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self[right_column_name]
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end
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# Returns true if this is a root node.
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def root?
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parent_id.nil?
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end
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def leaf?
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new_record? || (right - left == 1)
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end
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# Returns true is this is a child node
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def child?
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!parent_id.nil?
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end
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# order by left column
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def <=>(x)
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left <=> x.left
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end
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# Redefine to act like active record
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def ==(comparison_object)
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comparison_object.equal?(self) ||
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(comparison_object.instance_of?(self.class) &&
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comparison_object.id == id &&
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!comparison_object.new_record?)
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end
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# Returns root
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def root
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self_and_ancestors.find(:first)
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end
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# Returns the immediate parent
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def parent
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nested_set_scope.find_by_id(parent_id) if parent_id
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end
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# Returns the array of all parents and self
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def self_and_ancestors
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nested_set_scope.scoped :conditions => [
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"#{self.class.table_name}.#{quoted_left_column_name} <= ? AND #{self.class.table_name}.#{quoted_right_column_name} >= ?", left, right
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]
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end
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# Returns an array of all parents
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def ancestors
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without_self self_and_ancestors
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end
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# Returns the array of all children of the parent, including self
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def self_and_siblings
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nested_set_scope.scoped :conditions => {parent_column_name => parent_id}
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end
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# Returns the array of all children of the parent, except self
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def siblings
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without_self self_and_siblings
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end
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# Returns a set of all of its nested children which do not have children
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def leaves
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descendants.scoped :conditions => "#{self.class.table_name}.#{quoted_right_column_name} - #{self.class.table_name}.#{quoted_left_column_name} = 1"
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end
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# Returns the level of this object in the tree
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# root level is 0
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def level
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parent_id.nil? ? 0 : ancestors.count
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end
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# Returns a set of itself and all of its nested children
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def self_and_descendants
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nested_set_scope.scoped :conditions => [
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"#{self.class.table_name}.#{quoted_left_column_name} >= ? AND #{self.class.table_name}.#{quoted_right_column_name} <= ?", left, right
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]
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end
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# Returns a set of all of its children and nested children
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def descendants
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without_self self_and_descendants
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end
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# Returns a set of only this entry's immediate children
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def children
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nested_set_scope.scoped :conditions => {parent_column_name => self}
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end
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def is_descendant_of?(other)
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other.left < self.left && self.left < other.right && same_scope?(other)
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end
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def is_or_is_descendant_of?(other)
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other.left <= self.left && self.left < other.right && same_scope?(other)
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end
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def is_ancestor_of?(other)
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self.left < other.left && other.left < self.right && same_scope?(other)
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end
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def is_or_is_ancestor_of?(other)
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self.left <= other.left && other.left < self.right && same_scope?(other)
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end
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# Check if other model is in the same scope
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def same_scope?(other)
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Array(acts_as_nested_set_options[:scope]).all? do |attr|
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self.send(attr) == other.send(attr)
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end
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end
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# Find the first sibling to the left
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def left_sibling
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siblings.find(:first, :conditions => ["#{self.class.table_name}.#{quoted_left_column_name} < ?", left],
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:order => "#{self.class.table_name}.#{quoted_left_column_name} DESC")
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end
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# Find the first sibling to the right
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def right_sibling
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siblings.find(:first, :conditions => ["#{self.class.table_name}.#{quoted_left_column_name} > ?", left])
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end
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# Shorthand method for finding the left sibling and moving to the left of it.
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def move_left
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move_to_left_of left_sibling
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end
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# Shorthand method for finding the right sibling and moving to the right of it.
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def move_right
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move_to_right_of right_sibling
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end
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# Move the node to the left of another node (you can pass id only)
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def move_to_left_of(node)
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move_to node, :left
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end
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# Move the node to the left of another node (you can pass id only)
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def move_to_right_of(node)
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move_to node, :right
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end
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# Move the node to the child of another node (you can pass id only)
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def move_to_child_of(node)
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move_to node, :child
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end
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# Move the node to root nodes
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def move_to_root
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move_to nil, :root
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end
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def move_possible?(target)
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self != target && # Can't target self
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same_scope?(target) && # can't be in different scopes
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# !(left..right).include?(target.left..target.right) # this needs tested more
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# detect impossible move
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!((left <= target.left && right >= target.left) or (left <= target.right && right >= target.right))
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end
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def to_text
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self_and_descendants.map do |node|
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"#{'*'*(node.level+1)} #{node.id} #{node.to_s} (#{node.parent_id}, #{node.left}, #{node.right})"
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end.join("\n")
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end
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protected
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def without_self(scope)
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scope.scoped :conditions => ["#{self.class.table_name}.#{self.class.primary_key} != ?", self]
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end
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# All nested set queries should use this nested_set_scope, which performs finds on
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# the base ActiveRecord class, using the :scope declared in the acts_as_nested_set
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# declaration.
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def nested_set_scope
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options = {:order => "#{self.class.table_name}.#{quoted_left_column_name}"}
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scopes = Array(acts_as_nested_set_options[:scope])
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options[:conditions] = scopes.inject({}) do |conditions,attr|
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conditions.merge attr => self[attr]
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end unless scopes.empty?
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self.class.base_class.scoped options
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end
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# on creation, set automatically lft and rgt to the end of the tree
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def set_default_left_and_right
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maxright = nested_set_scope.maximum(right_column_name) || 0
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# adds the new node to the right of all existing nodes
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self[left_column_name] = maxright + 1
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self[right_column_name] = maxright + 2
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end
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# Prunes a branch off of the tree, shifting all of the elements on the right
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# back to the left so the counts still work.
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def prune_from_tree
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return if right.nil? || left.nil? || !self.class.exists?(id)
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self.class.base_class.transaction do
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reload_nested_set
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if acts_as_nested_set_options[:dependent] == :destroy
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children.each(&:destroy)
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else
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nested_set_scope.send(:delete_all,
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["#{quoted_left_column_name} > ? AND #{quoted_right_column_name} < ?",
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left, right]
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)
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end
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reload_nested_set
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diff = right - left + 1
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nested_set_scope.update_all(
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["#{quoted_left_column_name} = (#{quoted_left_column_name} - ?)", diff],
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["#{quoted_left_column_name} >= ?", right]
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)
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nested_set_scope.update_all(
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["#{quoted_right_column_name} = (#{quoted_right_column_name} - ?)", diff],
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["#{quoted_right_column_name} >= ?", right]
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)
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end
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# Reload is needed because children may have updated their parent (self) during deletion.
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reload
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end
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# reload left, right, and parent
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def reload_nested_set
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reload(:select => "#{quoted_left_column_name}, " +
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"#{quoted_right_column_name}, #{quoted_parent_column_name}")
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end
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def move_to(target, position)
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raise ActiveRecord::ActiveRecordError, "You cannot move a new node" if self.new_record?
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return if callback(:before_move) == false
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transaction do
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if target.is_a? self.class.base_class
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target.reload_nested_set
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elsif position != :root
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# load object if node is not an object
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target = nested_set_scope.find(target)
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end
|
|
self.reload_nested_set
|
|
|
|
unless position == :root || move_possible?(target)
|
|
raise ActiveRecord::ActiveRecordError, "Impossible move, target node cannot be inside moved tree."
|
|
end
|
|
|
|
bound = case position
|
|
when :child; target[right_column_name]
|
|
when :left; target[left_column_name]
|
|
when :right; target[right_column_name] + 1
|
|
when :root; 1
|
|
else raise ActiveRecord::ActiveRecordError, "Position should be :child, :left, :right or :root ('#{position}' received)."
|
|
end
|
|
|
|
if bound > self[right_column_name]
|
|
bound = bound - 1
|
|
other_bound = self[right_column_name] + 1
|
|
else
|
|
other_bound = self[left_column_name] - 1
|
|
end
|
|
|
|
# there would be no change
|
|
return if bound == self[right_column_name] || bound == self[left_column_name]
|
|
|
|
# we have defined the boundaries of two non-overlapping intervals,
|
|
# so sorting puts both the intervals and their boundaries in order
|
|
a, b, c, d = [self[left_column_name], self[right_column_name], bound, other_bound].sort
|
|
|
|
new_parent = case position
|
|
when :child; target.id
|
|
when :root; nil
|
|
else target[parent_column_name]
|
|
end
|
|
|
|
self.class.base_class.update_all([
|
|
"#{quoted_left_column_name} = CASE " +
|
|
"WHEN #{quoted_left_column_name} BETWEEN :a AND :b " +
|
|
"THEN #{quoted_left_column_name} + :d - :b " +
|
|
"WHEN #{quoted_left_column_name} BETWEEN :c AND :d " +
|
|
"THEN #{quoted_left_column_name} + :a - :c " +
|
|
"ELSE #{quoted_left_column_name} END, " +
|
|
"#{quoted_right_column_name} = CASE " +
|
|
"WHEN #{quoted_right_column_name} BETWEEN :a AND :b " +
|
|
"THEN #{quoted_right_column_name} + :d - :b " +
|
|
"WHEN #{quoted_right_column_name} BETWEEN :c AND :d " +
|
|
"THEN #{quoted_right_column_name} + :a - :c " +
|
|
"ELSE #{quoted_right_column_name} END, " +
|
|
"#{quoted_parent_column_name} = CASE " +
|
|
"WHEN #{self.class.base_class.primary_key} = :id THEN :new_parent " +
|
|
"ELSE #{quoted_parent_column_name} END",
|
|
{:a => a, :b => b, :c => c, :d => d, :id => self.id, :new_parent => new_parent}
|
|
], nested_set_scope.proxy_options[:conditions])
|
|
end
|
|
target.reload_nested_set if target
|
|
self.reload_nested_set
|
|
callback(:after_move)
|
|
end
|
|
|
|
end
|
|
|
|
end
|
|
end
|
|
end
|