Class: ActiveRecord::Associations::JoinDependency::JoinAssociation

Inherits:
JoinPart
  • Object
show all
Defined in:
lib/active_record/associations/join_dependency/join_association.rb

Overview

:nodoc:

Defined Under Namespace

Classes: JoinInformation

Instance Attribute Summary collapse

Attributes inherited from JoinPart

#base_klass, #children

Instance Method Summary collapse

Methods inherited from JoinPart

#each, #extract_record, #instantiate, #name

Constructor Details

#initialize(reflection, children) ⇒ JoinAssociation

Returns a new instance of JoinAssociation.



12
13
14
15
16
17
 
# File 'lib/active_record/associations/join_dependency/join_association.rb', line 12

def initialize(reflection, children)
  super(reflection.klass, children)

  @reflection      = reflection
  @tables          = nil
end

Instance Attribute Details

#reflection ⇒ Object (readonly)

The reflection of the association represented



8
9
10
 
# File 'lib/active_record/associations/join_dependency/join_association.rb', line 8

def reflection
  @reflection
end

#tables ⇒ Object

Returns the value of attribute tables.



10
11
12
 
# File 'lib/active_record/associations/join_dependency/join_association.rb', line 10

def tables
  @tables
end

Instance Method Details

#aliased_table_name ⇒ Object 



107
108
109
 
# File 'lib/active_record/associations/join_dependency/join_association.rb', line 107

def aliased_table_name
  table.table_alias || table.name
end

#build_constraint(klass, table, key, foreign_table, foreign_key) ⇒ Object

Builds equality condition.

Example:

class Physician < ActiveRecord::Base
  has_many :appointments
end

If I execute `Physician.joins(:appointments).to_a` then
  klass         # => Physician
  table         # => #<Arel::Table @name="appointments" ...>
  key           # =>  physician_id
  foreign_table # => #<Arel::Table @name="physicians" ...>
  foreign_key   # => id



90
91
92
93
94
95
96
97
98
99
100
101
 
# File 'lib/active_record/associations/join_dependency/join_association.rb', line 90

def build_constraint(klass, table, key, foreign_table, foreign_key)
  constraint = table[key].eq(foreign_table[foreign_key])

  if klass.finder_needs_type_condition?
    constraint = table.create_and([
      constraint,
      klass.send(:type_condition, table)
    ])
  end

  constraint
end

#join_constraints(foreign_table, foreign_klass, join_type, tables, chain) ⇒ Object 



26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
 
# File 'lib/active_record/associations/join_dependency/join_association.rb', line 26

def join_constraints(foreign_table, foreign_klass, join_type, tables, chain)
  joins         = []
  binds         = []
  tables        = tables.reverse

  # The chain starts with the target table, but we want to end with it here (makes
  # more sense in this context), so we reverse
  chain.reverse_each do |reflection|
    table = tables.shift
    klass = reflection.klass

    join_keys   = reflection.join_keys
    key         = join_keys.key
    foreign_key = join_keys.foreign_key

    constraint = build_constraint(klass, table, key, foreign_table, foreign_key)

    predicate_builder = PredicateBuilder.new(TableMetadata.new(klass, table))
    scope_chain_items = reflection.join_scopes(table, predicate_builder)
    klass_scope       = reflection.klass_join_scope(table, predicate_builder)

    scope_chain_items.concat [klass_scope].compact

    rel = scope_chain_items.inject(scope_chain_items.shift) do |left, right|
      left.merge right
    end

    if rel && !rel.arel.constraints.empty?
      binds += rel.bound_attributes
      constraint = constraint.and rel.arel.constraints
    end

    if reflection.type
      value = foreign_klass.base_class.name
      column = klass.columns_hash[reflection.type.to_s]

      binds << Relation::QueryAttribute.new(column.name, value, klass.type_for_attribute(column.name))
      constraint = constraint.and klass.arel_attribute(reflection.type, table).eq(Arel::Nodes::BindParam.new)
    end

    joins << table.create_join(table, table.create_on(constraint), join_type)

    # The current table in this iteration becomes the foreign table in the next
    foreign_table, foreign_klass = table, klass
  end

  JoinInformation.new joins, binds
end

#match?(other) ⇒ Boolean

Returns:

  • (Boolean) 


19
20
21
22
 
# File 'lib/active_record/associations/join_dependency/join_association.rb', line 19

def match?(other)
  return true if self == other
  super && reflection == other.reflection
end

#table ⇒ Object 



103
104
105
 
# File 'lib/active_record/associations/join_dependency/join_association.rb', line 103

def table
  tables.first
end