Module: DataMapper::DeepCloning

Defined in:
lib/dm-deep_cloning.rb,
lib/data_mapper/deep_cloning/utilities.rb

Defined Under Namespace

Modules: Utilities

Constant Summary collapse

DEFAULT_MODE = 
:new

Instance Method Summary collapse

Instance Method Details

#deep_clone(*args) ⇒ Object 



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# File 'lib/dm-deep_cloning.rb', line 26

def deep_clone(*args)
  mode = args.shift if [:new, :create].include?(args.first)
  mode ||= DEFAULT_MODE

  clone_relations = {}
  args.each do |arg|
    case arg
    when Hash
      Utilities::Hash.recursive_merge!(clone_relations, arg)
    when Array
      arg.each do |el|
        clone_relations[el] = {}
      end
    when Symbol
      clone_relations[arg] = {}
    else
      raise ArgumentError, "deep_clone only accepts Symbols, Hashes or Arrays"
    end
  end
  
  attrs = self.attributes.reject{ |(k, v)|
    self.class.properties[k].key? || k.to_s =~ /^(updated|created)_(at|on)$/
  }

  clone_relations.keys.each do |relationship_name|
    relationship = self.class.relationships[relationship_name]

    case relationship
    when DataMapper::Associations::OneToMany::Relationship, DataMapper::Associations::ManyToMany::Relationship
      attrs[relationship.name] = self.send(relationship.name).to_a.map do |related_object|
        # Q: Why `to_a`????
        # A: This is used to indirectly disable `eager_load` in the `attributes` method called in the following recursive call.
        # Q: Aha!!! But why???
        # A: It simply doesn't work with STI.
        # Q: f***!
        # A: Yea! Took me 3 hours.
        related_object.deep_clone(mode, clone_relations[relationship.name])
      end
      if attrs[relationship.name].empty?
        # Delete the atrribute if no objects need to be assigned to the relation.
        # dm-core seems to have a problem with Foo.new(:bars => []). Sadly
        # this was not reproduceable in the specs.
        attrs.delete(relationship.name)
      end
    when DataMapper::Associations::ManyToOne::Relationship
      attrs[relationship.name] = self.send(relationship.name).deep_clone(mode, clone_relations[relationship.name])
    else
      raise "Deep cloning failed: Unknown relationship '#{relationship_name}' in '#{self.class}'"
    end
  end

  self.class.send(mode, attrs)
end