### Home Classes Methods

### In Files

- lib/sequel/plugins/composition.rb

### Methods

- #composition
- #define_composition_accessor
- #inherited

### Files

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No matching classes.

# 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={}) click to toggle source

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]]

    # 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={}) click to toggle source

Define getter and setter methods for the composition object.

    # 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) click to toggle source

Copy the necessary class instance variables to the subclass.

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

[Validate]

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