Module: Sequel::Plugins::Composition::ClassMethods

Attributes

composition_module	[R]	A module included in the class holding the composition getter and setter methods.
compositions	[R]	A hash with composition name keys and composition reflection hash values.

Public Instance methods

composition(name, opts={})

Define a composition for this model, with name being the name of the composition. You must provide either a :mapping option or both the :composer and :decomposer options.

Options:

:class - if using the :mapping option, the class to use, as a Class, String or Symbol.
:composer - A proc that is instance evaled when the composition getter method is called to create the composition.
:decomposer - A proc that is instance evaled before saving the model object, if the composition object exists, which sets the columns in the model object based on the value of the composition object.

:mapping - An array where each element is either a symbol or an array of two symbols. A symbol is treated like an array of two symbols where both symbols are the same. The first symbol represents the getter method in the model, and the second symbol represents the getter method in the composition object. Example:

  # Uses columns year, month, and day in the current model
  # Uses year, month, and day methods in the composition object
  :mapping=>[:year, :month, :day]
  # Uses columns year, month, and day in the current model
  # Uses y, m, and d methods in the composition object where
  # for example y in the composition object represents year
  # in the model object.
  :mapping=>[[:year, :y], [:month, :m], [:day, :d]]

[Source]

    # File lib/sequel/plugins/composition.rb, line 60
60:         def composition(name, opts={})
61:           opts = opts.dup
62:           compositions[name] = opts
63:           if mapping = opts[:mapping]
64:             keys = mapping.map{|k| k.is_a?(Array) ? k.first : k}
65:             if !opts[:composer]              
66:               late_binding_class_option(opts, name)
67:               klass = opts[:class]
68:               class_proc = proc{klass || constantize(opts[:class_name])}
69:               opts[:composer] = proc do
70:                 if values = keys.map{|k| send(k)} and values.any?{|v| !v.nil?}
71:                   class_proc.call.new(*values)
72:                 else
73:                   nil
74:                 end
75:               end
76:             end
77:             if !opts[:decomposer]
78:               setter_meths = keys.map{|k| "#{k}=""#{k}="}
79:               cov_methods = mapping.map{|k| k.is_a?(Array) ? k.last : k}
80:               setters = setter_meths.zip(cov_methods)
81:               opts[:decomposer] = proc do
82:                 if (o = compositions[name]).nil?
83:                   setter_meths.each{|sm| send(sm, nil)}
84:                 else
85:                   setters.each{|sm, cm| send(sm, o.send(cm))}
86:                 end
87:               end
88:             end
89:           end
90:           raise(Error, "Must provide :composer and :decomposer options, or :mapping option") unless opts[:composer] && opts[:decomposer]
91:           define_composition_accessor(name, opts)
92:         end

define_composition_accessor(name, opts={})

Define getter and setter methods for the composition object.

[Source]

     # File lib/sequel/plugins/composition.rb, line 102
102:         def define_composition_accessor(name, opts={})
103:           include(@composition_module ||= Module.new) unless composition_module
104:           composer = opts[:composer]
105:           composition_module.class_eval do
106:             define_method(name) do 
107:               compositions.include?(name) ? compositions[name] : (compositions[name] = instance_eval(&composer))
108:             end
109:             define_method("#{name}=") do |v|
110:               modified!
111:               compositions[name] = v
112:             end
113:           end
114:         end

inherited(subclass)

Copy the necessary class instance variables to the subclass.

[Source]

    # File lib/sequel/plugins/composition.rb, line 95
95:         def inherited(subclass)
96:           super
97:           c = compositions.dup
98:           subclass.instance_eval{@compositions = c}
99:         end