Module: Og::Orderable

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

Overview

Attach list/ordering methods to the enchanted class.

Class Method Summary collapse

Class Method Details

.append_dynamic_features(base, options) ⇒ Object 



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# File 'lib/og/mixin/orderable.rb', line 9

def self.append_dynamic_features(base, options)
	o = { 
		:position => 'position', 
		:type => Fixnum, 
	}
	o.update(options) if options

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

	position = o[:position]
	scope = o[: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		

	code = %{		
		property :#{position}, #{o[:type]}

		pre "add_to_bottom", :on => :og_insert	
		pre "decrement_position_of_lower_items", :on => :og_delete
		
		def move_higher
			if higher = higher_item
				#{base}.transaction do
					higher.increment_position
					decrement_position
				end
			end
		end

		def move_lower
			if lower = lower_item
				#{base}.transaction do
					lower.decrement_position
					increment_position
				end
			end
		end

		def move_to_top
			#{base}.transaction do
				increment_position_of_higher_items
				set_top_position
			end
		end

		def move_to_bottom
			#{base}.transaction do
				decrement_position_of_lower_items
				set_bottom_position
			end											
		end

		def move_to
		end

		def add_to_top
			increment_position_of_all_items
		end

		def add_to_bottom
			@#{position} = bottom_position + 1
		end

		def add_to
		end

		def higher_item
			#{base}.one(#{cond_and}"#{position}=\#\{@#{position} - 1\}")
		end
		alias_method :previous_item, :higher_item

		def lower_item
			#{base}.one(#{cond_and}"#{position}=\#\{@#{position} + 1\}")
		end
		alias_method :next_item, :lower_item

		def top_item
		end
		alias_method :first_item, :top_item

		def bottom_item
			#{base}.one(#{cond}, :order => "#{position} DESC", :limit => 1)
		end
		alias_method :last_item, :last_item

		def top?
			@#{position} == 1
		end
		alias_method :first?, :top?

		def bottom?
			@#{position} == bottom_position
		end
		alias_method :last?, :bottom?

		def increment_position
			@#{position} += 1
			update(:#{position})
		end
	
		def decrement_position
			@#{position} -= 1
			update(:#{position})
		end

		def bottom_position
			item = bottom_item
			item ? item.#{position} : 0
		end

		def set_top_position
			@#{position} = 1
			update(:#{position})
		end

		def set_bottom_position
			@#{position} = bottom_position + 1
			update(:#{position})
		end

		def increment_position_of_higher_items
			#{base}.update_property("#{position}=(#{position} + 1)", #{cond_and}"#{position} < \#\{@#{position}\}")
		end

		def increment_position_of_all_items
			#{base}.update_property("#{position}=(#{position} + 1)", #{cond})
		end
		
		def decrement_position_of_lower_items
			#{base}.update_property("#{position}=(#{position} - 1)", #{cond_and}"#{position} > \#\{@#{position}\}")
		end
	}		
	
	base.module_eval(code)
end