Module: DelegateAllFor

Defined in:
lib/delegate_all_for.rb,
lib/delegate_all_for/version.rb

Constant Summary collapse

VERSION = 
"0.0.9"

Instance Method Summary collapse

Instance Method Details

#delegate_all_for(*attr_names) ⇒ Object

For all columns of the specified association to the current object, the reader, writer, and predicate methods are delegated.

Supported options:

:except

An array of column names to exclude from delegation

:also_include

An array of method names to also delegate

:prefix

Prefixes accessors. See the delegate documentation.

:allow_nil

Allows accessor to be nil. See the delegate documentation.



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# File 'lib/delegate_all_for.rb', line 23

def delegate_all_for(*attr_names)
  return unless self.table_exists?
  options = { except: [], also_include: [], prefix: false, allow_nil: false }
  options.update(attr_names.extract_options!)
  options.assert_valid_keys(:except, :also_include, :prefix, :allow_nil)

  exclude_columns = self.column_names.dup.concat(options[:except].map(&:to_s))
  attr_names.each do |association_name|
    if reflection = reflect_on_association(association_name)
      to = association_name
      delegate_opts = options.slice(:prefix, :allow_nil).merge(to: to)
      method_prefix = delegate_opts[:prefix] ? "#{prefix == true ? to : prefix}_" : ''

      options[:also_include].each do |m|
        class_eval(%{delegate :#{m}, #{delegate_opts}})
      end

      (reflection.klass.column_names - exclude_columns).each do |method|
        next if method.in?(reflection.foreign_key, 'updated_at', 'updated_on', 'created_at', 'created_on')
        class_eval <<-eoruby, __FILE__, __LINE__ + 1
          delegate :#{method},  #{delegate_opts}
          delegate :#{method}?, #{delegate_opts}
          delegate :#{method}=, #{delegate_opts.merge(allow_nil: false)} # allow_nil true leads to unintuitive behavior
        eoruby
      end
    else
      raise ArgumentError, "No association found for name `#{association_name}'. Has it been defined yet?"
    end
  end
end