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.



12
13
14
15
16
17
 
# 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. 



71
72
73
74
75
76
77
78
79
80
81
82
 
# File 'lib/rom/sql/association/many_to_many.rb', line 71

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 



20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
 
# 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))
    .order(*right.schema.project_pk.qualified)

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

#combine_keys(relations) ⇒ Object 



66
67
68
 
# File 'lib/rom/sql/association/many_to_many.rb', line 66

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

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



52
53
54
55
56
 
# File 'lib/rom/sql/association/many_to_many.rb', line 52

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 



59
60
61
62
63
 
# File 'lib/rom/sql/association/many_to_many.rb', line 59

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. 



85
86
87
 
# File 'lib/rom/sql/association/many_to_many.rb', line 85

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