Module: Glue::NestedSets

Defined in:
lib/glue/hierarchical.rb

Overview

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

Class Method Summary collapse

Class Method Details

.included_with_parameters(base, options) ⇒ Object 



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# File 'lib/glue/hierarchical.rb', line 14

def self.included_with_parameters 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 "    property :\#{parent}, Fixnum, :sql_index => true\n    property :\#{left}, :\#{right}, \#{c[:type]}\n\n    def root?\n      (@\#{parent}.nil? || @\#{parent} == 0) && (@\#{left} == 1) && (@\#{right} > @\#{left})\n    end\n\n    def child?\n      (@\#{parent} &&  @\#{parent} != 0) && (@\#{left} > 1) && (@\#{right} > @\#{left})\n    end\n\n    def parent\n      if root?\n        nil\n      else\n        \#{base}[@\#{parent}]\n      end\n    end\n\n    def \#{children}_count\n      return (@\#{right} - @\#{left} - 1)/2\n    end\n\n    def full_\#{children}(options = {})\n      options.update(\#{cond_and}\"(\#{left} BETWEEN \\#\\{@\#{left}\\} AND \\\#{@\#{right}})\")\n      \#{base}.all(options)\n    end\n\n    def \#{children}(options = {})\n      options.update(\#{cond_and}\"(\#{left} > \\#\\{@\#{left}\\}) AND (\#{right} < \\\#{@\#{right}})\")\n      \#{base}.all(options)\n    end\n\n    def direct_\#{children}(options = {})\n      options.update(\#{cond_and}\"\#{parent} = \\\#{pk}\")\n      \#{base}.all(options)\n    end\n\n    def add_\#{child}(child)\n      self.reload if pk\n      child.reload if child.pk\n\n      if @\#{left}.nil? || @\#{left} == 0 || @\#{right}.nil? || @\#{right} == 0\n        @\#{left} = 1\n        @\#{right} = 2 \n      end\n\n      child.\#{parent} = pk\n      child.\#{left} = pivot = @\#{right}\n      child.\#{right} = pivot + 1\n      @\#{right} = pivot + 2\n\n      \#{base}.transaction do\n        \#{base}.update(\"\#{left} = (\#{left} + 2)\",  \#{cond_and}\"\#{left} >= \\\#{pivot}\")\n        \#{base}.update(\"\#{right} = (\#{right} + 2)\", \#{cond_and}\"\#{right} >= \\\#{pivot}\")\n      end\n\n      self.save\n      child.save\n    end\n  EOE\nend\n", __FILE__, __LINE__