Module: Og::NestedSets

Defined in:
lib/og/mixin/hierarchical.rb

Overview

Implements the Nested Sets pattern for hierarchical SQL queries. – TODO: use active collections. ++

Class Method Summary collapse

Class Method Details

.append_dynamic_features(base, options) ⇒ Object 



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# File 'lib/og/mixin/hierarchical.rb', line 17

def self.append_dynamic_features(base, options)
	c = { 
		:left => 'lft', 
		:right => 'rgt', 
		:type => Fixnum, 
		:parent => base.to_s.demodulize.underscore.downcase,
		:children => base.to_s.demodulize.underscore.downcase.plural  
	}
	c.update(options) if options

	parent = "#{c[:parent]}_oid"
	left = c[:left]
	right = c[:right]
	children = c[:children]
	child = children.singular

 	if c[:scope].is_a?(Symbol) && c[:scope].to_s !~ /_oid$/
		c[:scope] = "#{c[:scope]}_oid".intern
	end

	scope = c[:scope]
	
	if scope
		if scope.is_a?(Symbol)
			scope = %{(#{scope} ? "#{scope} = \#{@#{scope}}" : "#{scope} IS NULL")}
		end
	
		cond = 'condition => ' + scope
		cond_and = ':condition => ' + scope + ' + " AND " +'
	else
		cond = ':condition => nil'
		cond_and = ':condition => '
	end		

	base.module_eval <<-EOE, __FILE__, __LINE__		
		property :#{parent}, Fixnum, :sql_index => true
		property :#{left}, :#{right}, #{c[:type]}

		def root?
			(@#{parent}.nil? || @#{parent} == 0) && (@#{left} == 1) && (@#{right} > @#{left})			
		end
	
		def child?
			(@#{parent} &&  @#{parent} != 0) && (@#{left} > 1) && (@#{right} > @#{left})			
		end
                                  
		def #{children}_count
			return (@#{right} - @#{left} - 1)/2
		end

		def full_#{children}(options = {})
			options.update(#{cond_and}"(#{left} BETWEEN \#\{@#{left}\} AND \#{@#{right}})")
			#{base}.all(options)
		end

		def #{children}(options = {})
			options.update(#{cond_and}"(#{left} > \#\{@#{left}\}) AND (#{right} < \#{@#{right}})")
			#{base}.all(options)
		end
													
		def direct_#{children}(options = {})
			options.update(#{cond_and}"#{parent} = \#{pk}")
			#{base}.all(options)
		end

		def add_#{child}(child)
			self.reload if pk
			child.reload if child.pk
			
			if @#{left}.nil? || @#{left} == 0 || @#{right}.nil? || @#{right} == 0
				@#{left} = 1
				@#{right} = 2 
			end
		
			child.#{parent} = pk
			child.#{left} = pivot = @#{right}
			child.#{right} = pivot + 1
			@#{right} = pivot + 2

			#{base}.transaction do
				#{base}.update_property("#{left} = (#{left} + 2)",  #{cond_and}"#{left} >= \#{pivot}")
				#{base}.update_property("#{right} = (#{right} + 2)", #{cond_and}"#{right} >= \#{pivot}")
			end
		
			self.save
			child.save
		end
	EOE
end