acts_as_filesystem.rb
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module ActsAsFilesystem
module ActsMethods
# Declares the ActiveRecord model to acts like a filesystem: objects are
# arranged in a tree (liks acts_as_tree), and . The underlying table must
# have the following fields:
#
# * name (+:string+) - the title of the object
# * slug (+:string+)- the title turned in a URL-friendly string (downcased,
# non-ascii chars transliterated into ascii, all sequences of
# non-alphanumericd characters changed into dashed)
# * path (+:text+)- stores the full path of the object (the full path of
# the parent, a "/" and the slug of the object)
# * children_count - a cache of the number of children elements.
def acts_as_filesystem
# a filesystem is a tree
acts_as_tree :counter_cache => :children_count
extend ClassMethods
include InstanceMethods
if self.has_path?
after_update :update_children_path
before_create :set_path
include InstanceMethods::PathMethods
end
before_save :set_ancestry
end
end
module ClassMethods
def build_ancestry(parent_id = nil, ancestry = '')
ActiveRecord::Base.transaction do
self.base_class.where(parent_id: parent_id).each do |node|
node.update_column :ancestry, ancestry
build_ancestry node.id, (ancestry.empty? ? "#{node.formatted_ancestry_id}" :
"#{ancestry}#{node.ancestry_sep}#{node.formatted_ancestry_id}")
end
end
#raise "Couldn't reach and set ancestry on every record" if self.base_class.where('ancestry is null').count != 0
end
def has_path?
(['name', 'slug', 'path'] - self.column_names).blank?
end
end
module InstanceMethods
def ancestry_column
'ancestry'
end
def ancestry_sep
'.'
end
def has_ancestry?
self.class.column_names.include? self.ancestry_column
end
def formatted_ancestry_id
"%010d" % self.id if self.id
end
def ancestry
self[ancestry_column]
end
def ancestor_ids
return nil if !has_ancestry? or ancestry.nil?
@ancestor_ids ||= ancestry.split(ancestry_sep).map{ |id| id.to_i }
end
def ancestry=(value)
self[ancestry_column] = value
end
def set_ancestry
return unless self.has_ancestry?
if self.ancestry.nil? or (new_record? or parent_id_changed?) or recalculate_path
self.ancestry = self.hierarchy(true)[0...-1].map{ |p| p.formatted_ancestry_id }.join(ancestry_sep)
end
end
def descendents_options
["#{self.ancestry_column} LIKE ?", "%#{self.formatted_ancestry_id}%"]
end
def descendents
self.class.where descendents_options
end
# calculates the level of the record in the records hierarchy. Top-level
# records have level 0; the children of the top-level records have
# level 1; the children of records with level 1 have level 2, and so on.
#
# A level 0
# / \
# B C level 1
# / \ / \
# E F G H level 2
# ...
def level
self.hierarchy.size - 1
end
# Is this record a top-level record?
def top_level?
self.parent.nil?
end
# Is this record a leaf in the hierarchy tree of records?
#
# Being a leaf means that this record has no subrecord.
def leaf?
self.children.empty?
end
def top_ancestor
if has_ancestry? and !ancestry.blank?
self.class.base_class.find_by id: self.top_ancestor_id
else
self.hierarchy.first
end
end
def top_ancestor_id
if has_ancestry? and !ancestry.nil?
self.ancestor_ids.first
else
self.hierarchy.first.id
end
end
# returns the full hierarchy from the top-level item to this one. For
# example, if item1 has a children item2 and item2 has a children item3,
# then item3's hierarchy would be [item1, item2, item3].
#
# If +reload+ is passed as +true+, then the hierarchy is reload (usefull
# when the ActiveRecord object was modified in some way, or just after
# changing parent)
def hierarchy(reload = false)
@hierarchy = nil if reload or recalculate_path
if @hierarchy.nil?
@hierarchy = []
if !reload and !recalculate_path and ancestor_ids
objects = self.class.base_class.where(id: ancestor_ids)
ancestor_ids.each{ |id| @hierarchy << objects.find{ |t| t.id == id } }
@hierarchy << self
else
item = self
while item
@hierarchy.unshift(item)
item = item.parent
end
end
end
@hierarchy
end
def map_traversal(&block)
result = []
current_level = [self]
while !current_level.empty?
result += current_level
ids = current_level.select {|item| item.children_count > 0}.map(&:id)
break if ids.empty?
current_level = self.class.base_class.where(parent_id: ids)
end
block ||= (lambda { |x| x })
result.map(&block)
end
def all_children
res = map_traversal
res.shift
res
end
#####
# Path methods
# These methods are used when _path_, _name_ and _slug_ attributes exist
# and should be calculated based on the tree
#####
module PathMethods
# used to know when to trigger batch renaming
attr_accessor :recalculate_path
# calculates the full path to this record using parent's path.
def calculate_path
self.hierarchy.map{ |obj| obj.slug }.join('/')
end
def set_path
if self.path == self.slug && !self.top_level?
self.path = self.calculate_path
end
end
def explode_path
path.split(/\//)
end
def update_children_path
if self.recalculate_path
self.children.each do |child|
child.path = child.calculate_path
child.recalculate_path = true
child.save!
end
end
self.recalculate_path = false
end
# calculates the full name of a record by accessing the name of all its
# ancestors.
#
# If you have this record hierarchy:
# Record "A"
# Record "B"
# Record "C"
#
# Then Record "C" will have "A/B/C" as its full name.
def full_name(sep = '/')
self.hierarchy.map {|item| item.name || '?' }.join(sep)
end
# gets the name without leading parents. Useful when dividing records
# in top-level groups and full names must not include the top-level
# record which is already a emphasized label
def full_name_without_leading(count, sep = '/')
parts = self.full_name(sep).split(sep)
count.times { parts.shift }
parts.join(sep)
end
def set_name(value)
if self.name != value
self.recalculate_path = true
end
self[:name] = value
end
# sets the name of the record. Also sets #slug accordingly.
def name=(value)
self.set_name(value)
unless self.name.blank?
self.slug = self.name.to_slug
end
end
# sets the slug of the record. Also sets the path with the new slug value.
def slug=(value)
self[:slug] = value
unless self.slug.blank?
self.path = self.calculate_path
end
end
end
end
end