Class: UnionOf::Reflection

Inherits:
ActiveRecord::Reflection::AssociationReflection
  • Object
show all
Defined in:
lib/union_of/reflection.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Reflection

Returns a new instance of Reflection.



7
8
9
10
11
 
# File 'lib/union_of/reflection.rb', line 7

def initialize(...)
  super

  @union_sources = @options[:sources]
end

Instance Attribute Details

#union_sources ⇒ Object (readonly)

Returns the value of attribute union_sources.



5
6
7
 
# File 'lib/union_of/reflection.rb', line 5

def union_sources
  @union_sources
end

Instance Method Details

#association_class ⇒ Object 



16
 
# File 'lib/union_of/reflection.rb', line 16

def association_class = UnionOf::Association

#association_scope_cache ⇒ Object

FIXME(ezekg) scope cache is borked

Raises:

  • (NotImplementedError) 


93
 
# File 'lib/union_of/reflection.rb', line 93

def association_scope_cache(...) = raise NotImplementedError

#collection? ⇒ Boolean

Returns:

  • (Boolean) 


15
 
# File 'lib/union_of/reflection.rb', line 15

def collection?       = true

#deconstruct_keys(keys) ⇒ Object 



95
 
# File 'lib/union_of/reflection.rb', line 95

def deconstruct_keys(keys) = { name:, options: }

#join_scope(table, foreign_table, foreign_klass, alias_tracker = nil) ⇒ Object 



19
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
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
 
# File 'lib/union_of/reflection.rb', line 19

def join_scope(table, foreign_table, foreign_klass, alias_tracker = nil)
  predicate_builder = predicate_builder(table)
  scope_chain_items = join_scopes(table, predicate_builder)
  klass_scope       = klass_join_scope(table, predicate_builder)

  # This holds our union's constraints. For example, if we're unioning across 3
  # tables, then this will hold constraints for all 3 of those tables, so that
  # the join on our target table mirrors the union of all 3 associations.
  foreign_constraints = []

  union_sources.each do |union_source|
    union_reflection = foreign_klass.reflect_on_association(union_source)

    if union_reflection.through_reflection?
      source_reflection  = union_reflection.source_reflection
      through_reflection = union_reflection.through_reflection
      through_klass      = through_reflection.klass
      through_table      = through_klass.arel_table

      # Alias table if we're provided with an alias tracker (i.e. via our #join_constraints overload)
      unless alias_tracker.nil?
        through_table = alias_tracker.aliased_table_for(through_table) do
          through_reflection.alias_candidate(union_source)
        end
      end

      # Create base join constraints and add default constraints if available
      through_constraint = through_table[through_reflection.join_primary_key].eq(
        foreign_table[through_reflection.join_foreign_key],
      )

      unless (where_clause = through_klass.default_scoped.where_clause).empty?
        through_constraint = where_clause.ast.and(through_constraint)
      end

      klass_scope.joins!(
        Arel::Nodes::OuterJoin.new(
          through_table,
          Arel::Nodes::On.new(through_constraint),
        ),
      )

      foreign_constraints << table[source_reflection.join_primary_key].eq(through_table[source_reflection.join_foreign_key])
    else
      foreign_constraints << table[union_reflection.join_primary_key].eq(foreign_table[union_reflection.join_foreign_key])
    end
  end

  unless foreign_constraints.empty?
    foreign_constraint = foreign_constraints.reduce(&:or)

    klass_scope.where!(foreign_constraint)
  end

  unless scope_chain_items.empty?
    scope_chain_items.reduce(klass_scope) do |scope, item|
      scope.merge!(item) # e.g. default scope constraints
    end

    # FIXME(ezekg) Wrapping the where clause in a grouping node so that Rails
    #              doesn't append our left outer joins a second time. This is
    #              because internally, during joining in #join_constraints,
    #              if Rails sees an Arel::Nodes::And node with predicates that
    #              don't match the current table, it'll concat all join
    #              sources. We don't want that, thus the hack.
    klass_scope.where_clause = ActiveRecord::Relation::WhereClause.new(
      [Arel::Nodes::Grouping.new(klass_scope.where_clause.ast)],
    )
  end

  klass_scope
end

#macro ⇒ Object 



13
 
# File 'lib/union_of/reflection.rb', line 13

def macro             = :union_of

#union_of? ⇒ Boolean

Returns:

  • (Boolean) 


14
 
# File 'lib/union_of/reflection.rb', line 14

def union_of?         = true

#union_reflections ⇒ Object 



17
 
# File 'lib/union_of/reflection.rb', line 17

def union_reflections = union_sources.collect { active_record.reflect_on_association(_1) }