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module CollectiveIdea #:nodoc:
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module Acts #:nodoc:
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module NestedSet #:nodoc:
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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.
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#
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# item.children.create(:name => "child1")
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#
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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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# * +:counter_cache+ adds a counter cache for the number of children.
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# defaults to false.
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# Example: <tt>acts_as_nested_set :counter_cache => :children_count</tt>
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#
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# See CollectiveIdea::Acts::NestedSet::Model::ClassMethods for a list of class methods and
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# CollectiveIdea::Acts::NestedSet::Model 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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:dependent => :delete_all, # or :destroy
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:counter_cache => false,
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:order => 'id'
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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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class_attribute :acts_as_nested_set_options
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self.acts_as_nested_set_options = options
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include CollectiveIdea::Acts::NestedSet::Model
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include Columns
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extend Columns
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belongs_to :parent, :class_name => self.base_class.to_s,
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:foreign_key => parent_column_name,
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:counter_cache => options[:counter_cache],
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:inverse_of => :children
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has_many :children, :class_name => self.base_class.to_s,
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:foreign_key => parent_column_name, :order => left_column_name,
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:inverse_of => :parent,
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:before_add => options[:before_add],
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:after_add => options[:after_add],
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:before_remove => options[:before_remove],
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:after_remove => options[:after_remove]
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attr_accessor :skip_before_destroy
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before_create :set_default_left_and_right
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before_save :store_new_parent
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after_save :move_to_new_parent
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before_destroy :destroy_descendants
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# no assignment to structure fields
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[left_column_name, right_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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define_model_callbacks :move
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end
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module Model
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extend ActiveSupport::Concern
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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.first
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end
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def roots
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where(parent_column_name => nil).order(quoted_left_column_name)
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end
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def leaves
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where("#{quoted_right_column_name} - #{quoted_left_column_name} = 1").order(quoted_left_column_name)
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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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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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where(
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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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).count == 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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select("#{scope_string}#{column}, COUNT(#{column})").
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group("#{scope_string}#{column}").
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having("COUNT(#{column}) > 1").
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first.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.
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# Also very useful for converting from acts_as_tree.
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def rebuild!(validate_nodes = true)
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# Don't rebuild a valid tree.
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return true if 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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where(["#{quoted_parent_column_name} = ? #{scope.call(node)}", node]).order(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!(:validate => validate_nodes)
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end
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# Find root node(s)
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root_nodes = where("#{quoted_parent_column_name} IS NULL").order(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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# Iterates over tree elements and determines the current level in the tree.
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# Only accepts default ordering, odering by an other column than lft
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# does not work. This method is much more efficent than calling level
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# because it doesn't require any additional database queries.
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#
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# Example:
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# Category.each_with_level(Category.root.self_and_descendants) do |o, level|
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#
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def each_with_level(objects)
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path = [nil]
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objects.each do |o|
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if o.parent_id != path.last
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# we are on a new level, did we decent or ascent?
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if path.include?(o.parent_id)
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# remove wrong wrong tailing paths elements
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path.pop while path.last != o.parent_id
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else
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path << o.parent_id
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end
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end
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yield(o, path.length - 1)
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end
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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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# 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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# Returns root
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def root
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self_and_ancestors.where(parent_column_name => nil).first
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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.where([
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"#{self.class.quoted_table_name}.#{quoted_left_column_name} <= ? AND #{self.class.quoted_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.where(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.where("#{self.class.quoted_table_name}.#{quoted_right_column_name} - #{self.class.quoted_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.where([
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"#{self.class.quoted_table_name}.#{quoted_left_column_name} >= ? AND #{self.class.quoted_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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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.where(["#{self.class.quoted_table_name}.#{quoted_left_column_name} < ?", left]).
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order("#{self.class.quoted_table_name}.#{quoted_left_column_name} DESC").last
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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.where(["#{self.class.quoted_table_name}.#{quoted_left_column_name} > ?", left]).first
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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.where(["#{self.class.quoted_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(options = {})
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options = {:order => "#{self.class.quoted_table_name}.#{quoted_left_column_name}"}.merge(options)
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|
394 |
scopes = Array(acts_as_nested_set_options[:scope])
|
|
395 |
options[:conditions] = scopes.inject({}) do |conditions,attr|
|
|
396 |
conditions.merge attr => self[attr]
|
|
397 |
end unless scopes.empty?
|
|
398 |
self.class.base_class.scoped options
|
|
399 |
end
|
|
400 |
|
|
401 |
def store_new_parent
|
|
402 |
@move_to_new_parent_id = send("#{parent_column_name}_changed?") ? parent_id : false
|
|
403 |
true # force callback to return true
|
|
404 |
end
|
|
405 |
|
|
406 |
def move_to_new_parent
|
|
407 |
if @move_to_new_parent_id.nil?
|
|
408 |
move_to_root
|
|
409 |
elsif @move_to_new_parent_id
|
|
410 |
move_to_child_of(@move_to_new_parent_id)
|
|
411 |
end
|
|
412 |
end
|
|
413 |
|
|
414 |
# on creation, set automatically lft and rgt to the end of the tree
|
|
415 |
def set_default_left_and_right
|
|
416 |
highest_right_row = nested_set_scope(:order => "#{quoted_right_column_name} desc").find(:first, :limit => 1,:lock => true )
|
|
417 |
maxright = highest_right_row ? (highest_right_row[right_column_name] || 0) : 0
|
|
418 |
# adds the new node to the right of all existing nodes
|
|
419 |
self[left_column_name] = maxright + 1
|
|
420 |
self[right_column_name] = maxright + 2
|
|
421 |
end
|
|
422 |
|
|
423 |
def in_tenacious_transaction(&block)
|
|
424 |
retry_count = 0
|
|
425 |
begin
|
|
426 |
transaction(&block)
|
|
427 |
rescue ActiveRecord::StatementInvalid => error
|
|
428 |
raise unless connection.open_transactions.zero?
|
|
429 |
raise unless error.message =~ /Deadlock found when trying to get lock|Lock wait timeout exceeded/
|
|
430 |
raise unless retry_count < 10
|
|
431 |
retry_count += 1
|
|
432 |
logger.info "Deadlock detected on retry #{retry_count}, restarting transaction"
|
|
433 |
sleep(rand(retry_count)*0.1) # Aloha protocol
|
|
434 |
retry
|
|
435 |
end
|
|
436 |
end
|
|
437 |
|
|
438 |
# Prunes a branch off of the tree, shifting all of the elements on the right
|
|
439 |
# back to the left so the counts still work.
|
|
440 |
def destroy_descendants
|
|
441 |
return if right.nil? || left.nil? || skip_before_destroy
|
|
442 |
|
|
443 |
in_tenacious_transaction do
|
|
444 |
reload_nested_set
|
|
445 |
# select the rows in the model that extend past the deletion point and apply a lock
|
|
446 |
self.class.base_class.find(:all,
|
|
447 |
:select => "id",
|
|
448 |
:conditions => ["#{quoted_left_column_name} >= ?", left],
|
|
449 |
:lock => true
|
|
450 |
)
|
|
451 |
|
|
452 |
if acts_as_nested_set_options[:dependent] == :destroy
|
|
453 |
descendants.each do |model|
|
|
454 |
model.skip_before_destroy = true
|
|
455 |
model.destroy
|
|
456 |
end
|
|
457 |
else
|
|
458 |
nested_set_scope.delete_all(
|
|
459 |
["#{quoted_left_column_name} > ? AND #{quoted_right_column_name} < ?",
|
|
460 |
left, right]
|
|
461 |
)
|
|
462 |
end
|
|
463 |
|
|
464 |
# update lefts and rights for remaining nodes
|
|
465 |
diff = right - left + 1
|
|
466 |
nested_set_scope.update_all(
|
|
467 |
["#{quoted_left_column_name} = (#{quoted_left_column_name} - ?)", diff],
|
|
468 |
["#{quoted_left_column_name} > ?", right]
|
|
469 |
)
|
|
470 |
nested_set_scope.update_all(
|
|
471 |
["#{quoted_right_column_name} = (#{quoted_right_column_name} - ?)", diff],
|
|
472 |
["#{quoted_right_column_name} > ?", right]
|
|
473 |
)
|
|
474 |
|
|
475 |
reload
|
|
476 |
# Don't allow multiple calls to destroy to corrupt the set
|
|
477 |
self.skip_before_destroy = true
|
|
478 |
end
|
|
479 |
end
|
|
480 |
|
|
481 |
# reload left, right, and parent
|
|
482 |
def reload_nested_set
|
|
483 |
reload(
|
|
484 |
:select => "#{quoted_left_column_name}, #{quoted_right_column_name}, #{quoted_parent_column_name}",
|
|
485 |
:lock => true
|
|
486 |
)
|
|
487 |
end
|
|
488 |
|
|
489 |
def move_to(target, position)
|
|
490 |
raise ActiveRecord::ActiveRecordError, "You cannot move a new node" if self.new_record?
|
|
491 |
run_callbacks :move do
|
|
492 |
in_tenacious_transaction do
|
|
493 |
if target.is_a? self.class.base_class
|
|
494 |
target.reload_nested_set
|
|
495 |
elsif position != :root
|
|
496 |
# load object if node is not an object
|
|
497 |
target = nested_set_scope.find(target)
|
|
498 |
end
|
|
499 |
self.reload_nested_set
|
|
500 |
|
|
501 |
unless position == :root || move_possible?(target)
|
|
502 |
raise ActiveRecord::ActiveRecordError, "Impossible move, target node cannot be inside moved tree."
|
|
503 |
end
|
|
504 |
|
|
505 |
bound = case position
|
|
506 |
when :child; target[right_column_name]
|
|
507 |
when :left; target[left_column_name]
|
|
508 |
when :right; target[right_column_name] + 1
|
|
509 |
when :root; 1
|
|
510 |
else raise ActiveRecord::ActiveRecordError, "Position should be :child, :left, :right or :root ('#{position}' received)."
|
|
511 |
end
|
|
512 |
|
|
513 |
if bound > self[right_column_name]
|
|
514 |
bound = bound - 1
|
|
515 |
other_bound = self[right_column_name] + 1
|
|
516 |
else
|
|
517 |
other_bound = self[left_column_name] - 1
|
|
518 |
end
|
|
519 |
|
|
520 |
# there would be no change
|
|
521 |
return if bound == self[right_column_name] || bound == self[left_column_name]
|
|
522 |
|
|
523 |
# we have defined the boundaries of two non-overlapping intervals,
|
|
524 |
# so sorting puts both the intervals and their boundaries in order
|
|
525 |
a, b, c, d = [self[left_column_name], self[right_column_name], bound, other_bound].sort
|
|
526 |
|
|
527 |
# select the rows in the model between a and d, and apply a lock
|
|
528 |
self.class.base_class.select('id').lock(true).where(
|
|
529 |
["#{quoted_left_column_name} >= :a and #{quoted_right_column_name} <= :d", {:a => a, :d => d}]
|
|
530 |
)
|
|
531 |
|
|
532 |
new_parent = case position
|
|
533 |
when :child; target.id
|
|
534 |
when :root; nil
|
|
535 |
else target[parent_column_name]
|
|
536 |
end
|
|
537 |
|
|
538 |
self.nested_set_scope.update_all([
|
|
539 |
"#{quoted_left_column_name} = CASE " +
|
|
540 |
"WHEN #{quoted_left_column_name} BETWEEN :a AND :b " +
|
|
541 |
"THEN #{quoted_left_column_name} + :d - :b " +
|
|
542 |
"WHEN #{quoted_left_column_name} BETWEEN :c AND :d " +
|
|
543 |
"THEN #{quoted_left_column_name} + :a - :c " +
|
|
544 |
"ELSE #{quoted_left_column_name} END, " +
|
|
545 |
"#{quoted_right_column_name} = CASE " +
|
|
546 |
"WHEN #{quoted_right_column_name} BETWEEN :a AND :b " +
|
|
547 |
"THEN #{quoted_right_column_name} + :d - :b " +
|
|
548 |
"WHEN #{quoted_right_column_name} BETWEEN :c AND :d " +
|
|
549 |
"THEN #{quoted_right_column_name} + :a - :c " +
|
|
550 |
"ELSE #{quoted_right_column_name} END, " +
|
|
551 |
"#{quoted_parent_column_name} = CASE " +
|
|
552 |
"WHEN #{self.class.base_class.primary_key} = :id THEN :new_parent " +
|
|
553 |
"ELSE #{quoted_parent_column_name} END",
|
|
554 |
{:a => a, :b => b, :c => c, :d => d, :id => self.id, :new_parent => new_parent}
|
|
555 |
])
|
|
556 |
end
|
|
557 |
target.reload_nested_set if target
|
|
558 |
self.reload_nested_set
|
|
559 |
end
|
|
560 |
end
|
|
561 |
|
|
562 |
end
|
|
563 |
|
|
564 |
# Mixed into both classes and instances to provide easy access to the column names
|
|
565 |
module Columns
|
|
566 |
def left_column_name
|
|
567 |
acts_as_nested_set_options[:left_column]
|
|
568 |
end
|
|
569 |
|
|
570 |
def right_column_name
|
|
571 |
acts_as_nested_set_options[:right_column]
|
|
572 |
end
|
|
573 |
|
|
574 |
def parent_column_name
|
|
575 |
acts_as_nested_set_options[:parent_column]
|
|
576 |
end
|
|
577 |
|
|
578 |
def scope_column_names
|
|
579 |
Array(acts_as_nested_set_options[:scope])
|
|
580 |
end
|
|
581 |
|
|
582 |
def quoted_left_column_name
|
|
583 |
connection.quote_column_name(left_column_name)
|
|
584 |
end
|
|
585 |
|
|
586 |
def quoted_right_column_name
|
|
587 |
connection.quote_column_name(right_column_name)
|
|
588 |
end
|
|
589 |
|
|
590 |
def quoted_parent_column_name
|
|
591 |
connection.quote_column_name(parent_column_name)
|
|
592 |
end
|
|
593 |
|
|
594 |
def quoted_scope_column_names
|
|
595 |
scope_column_names.collect {|column_name| connection.quote_column_name(column_name) }
|
|
596 |
end
|
|
597 |
end
|
|
598 |
|
|
599 |
end
|
|
600 |
end
|
|
601 |
end
|