Class: ROM::SQL::Association::ManyToMany

Inherits:
ROM::SQL::Association show all
Defined in:
lib/rom/sql/association/many_to_many.rb

Direct Known Subclasses

OneToOneThrough

Instance Method Summary collapse

Constructor Details

#initialize ⇒ ManyToMany

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.

Returns a new instance of ManyToMany.



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# File 'lib/rom/sql/association/many_to_many.rb', line 12

def initialize(*)
  super
  @through = Relation::Name[
    options[:through] || options[:through_relation], options[:through]
  ]
end

Instance Method Details

#associate(relations, children, parent) ⇒ 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. 



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# File 'lib/rom/sql/association/many_to_many.rb', line 69

def associate(relations, children, parent)
  ((spk, sfk), (tfk, tpk)) = join_key_map(relations)

  case parent
  when Array
    parent.map { |p| associate(relations, children, p) }.flatten(1)
  else
    children.map { |tuple|
      { sfk => tuple.fetch(spk), tfk => parent.fetch(tpk) }
    }
  end
end

#call(relations, target_rel = nil) ⇒ Object 



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# File 'lib/rom/sql/association/many_to_many.rb', line 20

def call(relations, target_rel = nil)
  join_rel = join_relation(relations)
  assocs = join_rel.associations

  left = target_rel ? assocs[target].(relations, target_rel) : assocs[target].(relations)
  right = relations[target.relation]

  left_fk = foreign_key || join_rel.foreign_key(source.relation)

  schema =
    if left.schema.key?(left_fk)
      if target_rel
        target_rel.schema.merge(left.schema.project(left_fk))
      else
        left.schema.project(*(right.schema.map(&:name) + [left_fk]))
      end
    else
      right.schema.merge(join_rel.schema.project(left_fk))
    end.qualified

  relation = left.inner_join(source, join_keys(relations))

  if view
    apply_view(schema, relation)
  else
    schema.(relation)
  end
end

#combine_keys(relations) ⇒ Object 



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# File 'lib/rom/sql/association/many_to_many.rb', line 64

def combine_keys(relations)
  Hash[*with_keys(relations)]
end

#join(relations, type, source = , target = ) ⇒ Object 



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# File 'lib/rom/sql/association/many_to_many.rb', line 50

def join(relations, type, source = relations[self.source], target = relations[self.target])
  through_assoc = source.associations[through]
  joined = through_assoc.join(relations, type, source)
  joined.__send__(type, target.name.dataset, join_keys(relations)).qualified
end

#join_keys(relations) ⇒ Object 



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# File 'lib/rom/sql/association/many_to_many.rb', line 57

def join_keys(relations)
  with_keys(relations) { |source_key, target_key|
    { qualify(source, source_key) => qualify(through, target_key) }
  }
end

#join_relation(relations) ⇒ 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. 



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# File 'lib/rom/sql/association/many_to_many.rb', line 83

def join_relation(relations)
  relations[through.relation]
end