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

Defined in:
lib/sequel/plugins/composition.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Instance Attribute Details

#composition_module ⇒ Object (readonly)

A module included in the class holding the composition getter and setter methods.



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# File 'lib/sequel/plugins/composition.rb', line 36

def composition_module
  @composition_module
end

#compositions ⇒ Object (readonly)

A hash with composition name keys and composition reflection hash values.



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# File 'lib/sequel/plugins/composition.rb', line 32

def compositions
  @compositions
end

Instance Method Details

#composition(name, opts = {}) ⇒ Object

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]]

Raises:



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# File 'lib/sequel/plugins/composition.rb', line 60

def composition(name, opts={})
  opts = opts.dup
  compositions[name] = opts
  if mapping = opts[:mapping]
    keys = mapping.map{|k| k.is_a?(Array) ? k.first : k}
    if !opts[:composer]              
      late_binding_class_option(opts, name)
      klass = opts[:class]
      class_proc = proc{klass || constantize(opts[:class_name])}
      opts[:composer] = proc do
        if values = keys.map{|k| send(k)} and values.any?{|v| !v.nil?}
          class_proc.call.new(*values)
        else
          nil
        end
      end
    end
    if !opts[:decomposer]
      setter_meths = keys.map{|k| :"#{k}="}
      cov_methods = mapping.map{|k| k.is_a?(Array) ? k.last : k}
      setters = setter_meths.zip(cov_methods)
      opts[:decomposer] = proc do
        if (o = compositions[name]).nil?
          setter_meths.each{|sm| send(sm, nil)}
        else
          setters.each{|sm, cm| send(sm, o.send(cm))}
        end
      end
    end
  end
  raise(Error, "Must provide :composer and :decomposer options, or :mapping option") unless opts[:composer] && opts[:decomposer]
  define_composition_accessor(name, opts)
end

#define_composition_accessor(name, opts = {}) ⇒ Object

Define getter and setter methods for the composition object.



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# File 'lib/sequel/plugins/composition.rb', line 102

def define_composition_accessor(name, opts={})
  include(@composition_module ||= Module.new) unless composition_module
  composer = opts[:composer]
  composition_module.class_eval do
    define_method(name) do 
      compositions.include?(name) ? compositions[name] : (compositions[name] = instance_eval(&composer))
    end
    define_method("#{name}=") do |v|
      modified!
      compositions[name] = v
    end
  end
end

#inherited(subclass) ⇒ Object

Copy the necessary class instance variables to the subclass.



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# File 'lib/sequel/plugins/composition.rb', line 95

def inherited(subclass)
  super
  c = compositions.dup
  subclass.instance_eval{@compositions = c}
end