Added a setter for parents=.

ancestry.gemspec

@@ -1,26 +1,30 @@
+# -*- encoding: utf-8 -*-
+# stub: ancestry 2.1.4 ruby lib
+
 Gem::Specification.new do |s|
-  s.name        = 'ancestry'
-  s.description = 'Organise ActiveRecord model into a tree structure'
-  s.summary     = 'Ancestry allows the records of a ActiveRecord model to be organised in a tree structure, using a single, intuitively formatted database column. It exposes all the standard tree structure relations (ancestors, parent, root, children, siblings, descendants) and all of them can be fetched in a single sql query. Additional features are named_scopes, integrity checking, integrity restoration, arrangement of (sub)tree into hashes and different strategies for dealing with orphaned records.'
+  s.name = "ancestry"
+  s.version = "2.1.4"
 
-  s.version = '2.1.4'
+  s.required_rubygems_version = Gem::Requirement.new(">= 0") if s.respond_to? :required_rubygems_version=
+  s.require_paths = ["lib"]
+  s.authors = ["Stefan Kroes [enhancements for multi-parent nodes by tjchambers]"]
+  s.date = "2015-01-22"
+  s.description = "Organise ActiveRecord model into a tree structure"
+  s.email = "[email protected]"
+  s.files = ["MIT-LICENSE", "README.rdoc", "ancestry.gemspec", "init.rb", "install.rb", "lib/ancestry.rb", "lib/ancestry/class_methods.rb", "lib/ancestry/exceptions.rb", "lib/ancestry/has_ancestry.rb", "lib/ancestry/instance_methods.rb"]
+  s.homepage = "http://github.com/tjchambers/ancestry"
+  s.rubygems_version = "2.4.3"
+  s.summary = "Ancestry allows the records of a ActiveRecord model to be organised in a tree structure, using a single, intuitively formatted database column. It exposes all the standard tree structure relations (ancestors, parent, root, children, siblings, descendants) and all of them can be fetched in a single sql query. Additional features are named_scopes, integrity checking, integrity restoration, arrangement of (sub)tree into hashes and different strategies for dealing with orphaned records."
 
-  s.author   = 'Stefan Kroes [enhancements for multi-parent nodes by tjchambers]'
-  s.email    = '[email protected]'
-  s.homepage = 'http://github.com/tjchambers/ancestry'
+  if s.respond_to? :specification_version then
+    s.specification_version = 4
 
-  s.files = [
-    'ancestry.gemspec', 
-    'init.rb', 
-    'install.rb', 
-    'lib/ancestry.rb', 
-    'lib/ancestry/has_ancestry.rb', 
-    'lib/ancestry/exceptions.rb', 
-    'lib/ancestry/class_methods.rb', 
-    'lib/ancestry/instance_methods.rb', 
-    'MIT-LICENSE', 
-    'README.rdoc'
-  ]
-
-  s.add_dependency 'activerecord', '>= 4.0.0'
+    if Gem::Version.new(Gem::VERSION) >= Gem::Version.new('1.2.0') then
+      s.add_runtime_dependency(%q<activerecord>, [">= 4.0.0"])
+    else
+      s.add_dependency(%q<activerecord>, [">= 4.0.0"])
+    end
+  else
+    s.add_dependency(%q<activerecord>, [">= 4.0.0"])
+  end
 end

lib/ancestry.rb

@@ -4,5 +4,7 @@
 require File.join(File.expand_path(File.dirname(__FILE__)), 'ancestry/has_ancestry')
 
 module Ancestry
-  ANCESTRY_PATTERN = /\A[0-9]+(\/[0-9]+)*(,[0-9]+(\/[0-9]+)*)*\Z/
+  # ANCESTRY_PATTERN = /\A[0-9]+(\/[0-9]+)*(,[0-9]+(\/[0-9]+)*)*\Z/
+  # This was modified to cycle through an array of values that may match this pattern, rather than 1 value
+  ANCESTRY_PATTERN = /[\A[0-9]+(\/[0-9]+)*([0-9]+(\/[0-9]+)*)*\Z]/  
 end

lib/ancestry/instance_methods.rb

@@ -125,6 +125,18 @@ def parent_id=(parent_id)
                     end
     end
 
+    ## These were re-added to give single parent functionality
+
+    def parent
+      if parent_id.blank? then nil else unscoped_find(parent_id) end
+    end
+
+    def parent_id
+      if ancestor_ids.empty? then nil else ancestor_ids.last end
+    end
+
+    ## These were re-added to give single parent functionality    
+
     # branches are the multiple parents of the current node
     def branches
       if ancestor_ids.empty? then
@@ -150,11 +162,30 @@ def parents
         unscoped_find(parent_ids)
       end
     end
+
+    def parents=(new_parents)
+      ancestry = if new_parents.nil?
+                   nil
+                 else
+                   # This is for the single ID case                   
+                   # (self.base_class.find(new_parents).child_ancestry.split("/") - [self.id.to_s]).join("/")
+
+                   # What this does is finds the new record in the DB, gets the child_ancestry value for that new
+                   # record - which is the ancestry path of the entire tree, but that includes the ID for the current
+                   # node, so we remove the current node from the child_ancestry path, convert it back into an
+                   # ancestry-friendly string and return that entire thing.                   
+
+                   # This is for an list of ancestry values
+                   (new_parents.collect { |x| (self.base_class.find(x).child_ancestry.split("/") - [self.id.to_s]).join("/") }).join(",")
+                 end
+                 # binding.pry
+      write_attribute(self.base_class.ancestry_column, ancestry)
+    end
 
     def has_parent?
       !is_root?
     end
-
+    
     # Root - the topmost SINGULAR node of the current tree
     def root_id
       if ancestor_ids.empty? then
@@ -175,6 +206,56 @@ def root
     def is_root?
       read_attribute(self.base_class.ancestry_column).blank?
     end
+
+    # Children
+
+    def child_conditions
+      t = get_arel_table
+      t[get_ancestry_column].eq(child_ancestry)
+    end
+
+    def children
+      self.base_class.where child_conditions
+    end
+
+    def child_ids
+      children.select(self.base_class.primary_key).map(&self.base_class.primary_key.to_sym)
+    end
+
+    def has_children?
+      self.children.exists?({})
+    end
+    alias_method :children?, :has_children?
+
+    def is_childless?
+      !has_children?
+    end
+    alias_method :childless?, :is_childless?
+
+    # Siblings
+
+    def sibling_conditions
+      t = get_arel_table
+      t[get_ancestry_column].eq(read_attribute(self.base_class.ancestry_column))
+    end
+
+    def siblings
+      self.base_class.where sibling_conditions
+    end
+
+    def sibling_ids
+      siblings.select(self.base_class.primary_key).collect(&self.base_class.primary_key.to_sym)
+    end
+
+    def has_siblings?
+      self.siblings.count > 1
+    end
+    alias_method :siblings?, :has_siblings?
+
+    def is_only_child?
+      !has_siblings?
+    end
+    alias_method :only_child?, :is_only_child?
 
 
     # Descendants = all the nodes below and NOT including the current node
@@ -262,11 +343,23 @@ def unscoped_descendants
     # basically validates the ancestry, but also applied if validation is
     # bypassed to determine if children should be affected
     def sane_ancestry?
-      ancestry.nil? || (ancestry.to_s =~ Ancestry::ANCESTRY_PATTERN && !ancestor_ids.include?(self.id))
+      ancestry.nil? || (ancestry.to_s =~ Ancestry::ANCESTRY_PATTERN && !ancestor_ids.include?(self.id))      
     end
 
     def unscoped_find(id)
       self.base_class.unscoped { self.base_class.find(id) }
     end
+
+    def get_arel_table
+      self.base_class.arel_table
+    end
+
+    def get_primary_key_column
+      self.base_class.primary_key.to_sym
+    end
+
+    def get_ancestry_column
+      self.base_class.ancestry_column.to_sym
+    end
   end
 end