1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
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
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
|
module ActiveRecord
module Reflection # :nodoc:
def self.included(base)
base.extend(ClassMethods)
end
# Reflection allows you to interrogate Active Record classes and objects about their associations and aggregations.
# This information can, for example, be used in a form builder that took an Active Record object and created input
# fields for all of the attributes depending on their type and displayed the associations to other objects.
#
# You can find the interface for the AggregateReflection and AssociationReflection classes in the abstract MacroReflection class.
module ClassMethods
def create_reflection(macro, name, options, active_record)
case macro
when :has_many, :belongs_to, :has_one, :has_and_belongs_to_many
reflection = AssociationReflection.new(macro, name, options, active_record)
when :composed_of
reflection = AggregateReflection.new(macro, name, options, active_record)
end
write_inheritable_hash :reflections, name => reflection
reflection
end
# Returns a hash containing all AssociationReflection objects for the current class
# Example:
#
# Invoice.reflections
# Account.reflections
#
def reflections
read_inheritable_attribute(:reflections) || write_inheritable_attribute(:reflections, {})
end
# Returns an array of AggregateReflection objects for all the aggregations in the class.
def reflect_on_all_aggregations
reflections.values.select { |reflection| reflection.is_a?(AggregateReflection) }
end
# Returns the AggregateReflection object for the named +aggregation+ (use the symbol). Example:
#
# Account.reflect_on_aggregation(:balance) # returns the balance AggregateReflection
#
def reflect_on_aggregation(aggregation)
reflections[aggregation].is_a?(AggregateReflection) ? reflections[aggregation] : nil
end
# Returns an array of AssociationReflection objects for all the associations in the class. If you only want to reflect on a
# certain association type, pass in the symbol (:has_many, :has_one, :belongs_to) for that as the first parameter.
# Example:
#
# Account.reflect_on_all_associations # returns an array of all associations
# Account.reflect_on_all_associations(:has_many) # returns an array of all has_many associations
#
def reflect_on_all_associations(macro = nil)
association_reflections = reflections.values.select { |reflection| reflection.is_a?(AssociationReflection) }
macro ? association_reflections.select { |reflection| reflection.macro == macro } : association_reflections
end
# Returns the AssociationReflection object for the named +association+ (use the symbol). Example:
#
# Account.reflect_on_association(:owner) # returns the owner AssociationReflection
# Invoice.reflect_on_association(:line_items).macro # returns :has_many
#
def reflect_on_association(association)
reflections[association].is_a?(AssociationReflection) ? reflections[association] : nil
end
end
# Abstract base class for AggregateReflection and AssociationReflection that describes the interface available for both of
# those classes. Objects of AggregateReflection and AssociationReflection are returned by the Reflection::ClassMethods.
class MacroReflection
attr_reader :active_record
def initialize(macro, name, options, active_record)
@macro, @name, @options, @active_record = macro, name, options, active_record
end
# Returns the name of the macro, so it would return :balance for "composed_of :balance, :class_name => 'Money'" or
# :clients for "has_many :clients".
def name
@name
end
# Returns the type of the macro, so it would return :composed_of for
# "composed_of :balance, :class_name => 'Money'" or :has_many for "has_many :clients".
def macro
@macro
end
# Returns the hash of options used for the macro, so it would return { :class_name => "Money" } for
# "composed_of :balance, :class_name => 'Money'" or {} for "has_many :clients".
def options
@options
end
# Returns the class for the macro, so "composed_of :balance, :class_name => 'Money'" returns the Money class and
# "has_many :clients" returns the Client class.
def klass
@klass ||= class_name.constantize
end
def class_name
@class_name ||= options[:class_name] || derive_class_name
end
def ==(other_aggregation)
name == other_aggregation.name && other_aggregation.options && active_record == other_aggregation.active_record
end
private
def derive_class_name
name.to_s.camelize
end
end
# Holds all the meta-data about an aggregation as it was specified in the Active Record class.
class AggregateReflection < MacroReflection #:nodoc:
end
# Holds all the meta-data about an association as it was specified in the Active Record class.
class AssociationReflection < MacroReflection #:nodoc:
def klass
@klass ||= active_record.send(:compute_type, class_name)
end
def table_name
@table_name ||= klass.table_name
end
def primary_key_name
@primary_key_name ||= options[:foreign_key] || derive_primary_key_name
end
def association_foreign_key
@association_foreign_key ||= @options[:association_foreign_key] || class_name.foreign_key
end
def counter_cache_column
if options[:counter_cache] == true
"#{active_record.name.underscore.pluralize}_count"
elsif options[:counter_cache]
options[:counter_cache]
end
end
def through_reflection
@through_reflection ||= options[:through] ? active_record.reflect_on_association(options[:through]) : false
end
# Gets an array of possible :through source reflection names
#
# [singularized, pluralized]
#
def source_reflection_names
@source_reflection_names ||= (options[:source] ? [options[:source]] : [name.to_s.singularize, name]).collect { |n| n.to_sym }
end
# Gets the source of the through reflection. It checks both a singularized and pluralized form for :belongs_to or :has_many.
# (The :tags association on Tagging below)
#
# class Post
# has_many :tags, :through => :taggings
# end
#
def source_reflection
return nil unless through_reflection
@source_reflection ||= source_reflection_names.collect { |name| through_reflection.klass.reflect_on_association(name) }.compact.first
end
def check_validity!
if options[:through]
if through_reflection.nil?
raise HasManyThroughAssociationNotFoundError.new(active_record.name, self)
end
if source_reflection.nil?
raise HasManyThroughSourceAssociationNotFoundError.new(self)
end
if options[:source_type] && source_reflection.options[:polymorphic].nil?
raise HasManyThroughAssociationPointlessSourceTypeError.new(active_record.name, self, source_reflection)
end
if source_reflection.options[:polymorphic] && options[:source_type].nil?
raise HasManyThroughAssociationPolymorphicError.new(active_record.name, self, source_reflection)
end
unless [:belongs_to, :has_many].include?(source_reflection.macro) && source_reflection.options[:through].nil?
raise HasManyThroughSourceAssociationMacroError.new(self)
end
end
end
private
def derive_class_name
# get the class_name of the belongs_to association of the through reflection
if through_reflection
options[:source_type] || source_reflection.class_name
else
class_name = name.to_s.camelize
class_name = class_name.singularize if [ :has_many, :has_and_belongs_to_many ].include?(macro)
class_name
end
end
def derive_primary_key_name
if macro == :belongs_to
"#{name}_id"
elsif options[:as]
"#{options[:as]}_id"
else
active_record.name.foreign_key
end
end
end
end
end
|
