Module: DataMapper::Model::Relationship

Extended by:
Chainable
Includes:
Assertions
Defined in:
lib/dm-core/model/relationship.rb

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Chainable

chainable, extendable

Methods included from Assertions

#assert_kind_of

Class Method Details

.extended(model) ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Initializes relationships hash for extended model class.

When model calls has n, has 1 or belongs_to, relationships are stored in that hash: keys are repository names and values are relationship sets.



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# File 'lib/dm-core/model/relationship.rb', line 22

def self.extended(model)
  model.instance_variable_set(:@relationships, {})
end

Instance Method Details

#belongs_to(name, *args) ⇒ Association::Relationship

A shorthand, clear syntax for defining many-to-one resource relationships.

* belongs_to :user                              # many to one user
* belongs_to :friend, :model => 'User'          # many to one friend
* belongs_to :reference, :repository => :pubmed # association for repository other than default

Parameters:

  • name (Symbol) —

    the name that the association will be referenced by

  • *args (Model, Hash) —

    model and/or options hash

Returns:

  • (Association::Relationship) —

    The association created should not be accessed directly



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# File 'lib/dm-core/model/relationship.rb', line 161

def belongs_to(name, *args)
  name       = name.to_sym
  model_name = self.name
  model      = extract_model(args)
  options    = extract_options(args)

  if options.key?(:through)
    raise "#{model_name}#belongs_to with :through is deprecated, use 'has 1, :#{name}, #{options.inspect}' in #{model_name} instead (#{caller.first})"
  elsif options.key?(:model) && model
    raise ArgumentError, 'should not specify options[:model] if passing the model in the third argument'
  end

  assert_valid_options(options)

  model ||= options.delete(:model)

  repository_name = repository.name

  # TODO: change to source_repository_name and target_respository_name
  options[:child_repository_name]  = repository_name
  options[:parent_repository_name] = options.delete(:repository)

  relationship = Associations::ManyToOne::Relationship.new(name, self, model, options)

  relationships(repository_name) << relationship

  descendants.each do |descendant|
    descendant.relationships(repository_name) << relationship
  end

  create_relationship_reader(relationship)
  create_relationship_writer(relationship)

  relationship
end

#has(cardinality, name, *args) ⇒ Association::Relationship

A shorthand, clear syntax for defining one-to-one, one-to-many and many-to-many resource relationships.

* has 1,    :friend                             # one friend
* has n,    :friends                            # many friends
* has 1..3, :friends                            # many friends (at least 1, at most 3)
* has 3,    :friends                            # many friends (exactly 3)
* has 1,    :friend,  'User'                    # one friend with the class User
* has 3,    :friends, :through => :friendships  # many friends through the friendships relationship

Parameters:

  • cardinality (Integer, Range, Infinity) —

    cardinality that defines the association type and constraints

  • name (Symbol) —

    the name that the association will be referenced by

  • *args (Model, Hash) —

    model and/or options hash

Returns:

  • (Association::Relationship) —

    the relationship that was created to reflect either a one-to-one, one-to-many or many-to-many relationship

Raises:

  • (ArgumentError) —

    if the cardinality was not understood. Should be a Integer, Range or Infinity(n)



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# File 'lib/dm-core/model/relationship.rb', line 101

def has(cardinality, name, *args)
  name    = name.to_sym
  model   = extract_model(args)
  options = extract_options(args)

  min, max = extract_min_max(cardinality)
  options.update(:min => min, :max => max)

  assert_valid_options(options)

  if options.key?(:model) && model
    raise ArgumentError, 'should not specify options[:model] if passing the model in the third argument'
  end

  model ||= options.delete(:model)

  repository_name = repository.name

  # TODO: change to :target_respository_name and :source_repository_name
  options[:child_repository_name]  = options.delete(:repository)
  options[:parent_repository_name] = repository_name

  klass = if max > 1
    options.key?(:through) ? Associations::ManyToMany::Relationship : Associations::OneToMany::Relationship
  else
    Associations::OneToOne::Relationship
  end

  relationship = klass.new(name, model, self, options)

  relationships(repository_name) << relationship

  descendants.each do |descendant|
    descendant.relationships(repository_name) << relationship
  end

  create_relationship_reader(relationship)
  create_relationship_writer(relationship)

  relationship
end

#n ⇒ Object

Used to express unlimited cardinality of association, see has



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# File 'lib/dm-core/model/relationship.rb', line 68

def n
  Infinity
end

#relationships(repository_name = default_repository_name) ⇒ RelationshipSet

Returns copy of relationships set in given repository.

Parameters:

  • repository_name (Symbol) (defaults to: default_repository_name) —

    Name of the repository for which relationships set is returned

Returns:



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# File 'lib/dm-core/model/relationship.rb', line 50

def relationships(repository_name = default_repository_name)
  # TODO: create RelationshipSet#copy that will copy the relationships, but assign the
  # new Relationship objects to a supplied repository and model.  dup does not really
  # do what is needed

  default_repository_name = self.default_repository_name

  @relationships[repository_name] ||= if repository_name == default_repository_name
    RelationshipSet.new
  else
    relationships(default_repository_name).dup
  end
end