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
|
module ActiveRecord
module Reflection # :nodoc:
def self.append_features(base)
super
base.extend(ClassMethods)
base.class_eval do
class << self
alias_method :composed_of_without_reflection, :composed_of
def composed_of_with_reflection(part_id, options = {})
composed_of_without_reflection(part_id, options)
reflect_on_all_aggregations << AggregateReflection.new(:composed_of, part_id, options, self)
end
alias_method :composed_of, :composed_of_with_reflection
end
end
for association_type in %w( belongs_to has_one has_many has_and_belongs_to_many )
base.module_eval <<-"end_eval"
class << self
alias_method :#{association_type}_without_reflection, :#{association_type}
def #{association_type}_with_reflection(association_id, options = {})
#{association_type}_without_reflection(association_id, options)
reflect_on_all_associations << AssociationReflection.new(:#{association_type}, association_id, options, self)
end
alias_method :#{association_type}, :#{association_type}_with_reflection
end
end_eval
end
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
# Returns an array of AggregateReflection objects for all the aggregations in the class.
def reflect_on_all_aggregations
read_inheritable_attribute(:aggregations) or write_inheritable_attribute(:aggregations, [])
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)
reflect_on_all_aggregations.find { |reflection| reflection.name == aggregation } unless reflect_on_all_aggregations.nil?
end
# Returns an array of AssociationReflection objects for all the aggregations in the class.
def reflect_on_all_associations
read_inheritable_attribute(:associations) or write_inheritable_attribute(:associations, [])
end
# Returns the AssociationReflection object for the named +aggregation+ (use the symbol). Example:
# Account.reflect_on_association(:owner) # returns the owner AssociationReflection
def reflect_on_association(association)
reflect_on_all_associations.find { |reflection| reflection.name == association }
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 name 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'" would return the Money class and
# "has_many :clients" would return the Client class.
def klass() end
def ==(other_aggregation)
name == other_aggregation.name && other_aggregation.options && active_record == other_aggregation.active_record
end
end
# Holds all the meta-data about an aggregation as it was specified in the Active Record class.
class AggregateReflection < MacroReflection #:nodoc:
def klass
Object.const_get(options[:class_name] || name_to_class_name(name.id2name))
end
private
def name_to_class_name(name)
name.capitalize.gsub(/_(.)/) { |s| $1.capitalize }
end
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, (name_to_class_name(name.id2name)))
end
def table_name
@table_name ||= klass.table_name
end
private
def name_to_class_name(name)
if name =~ /::/
name
else
unless class_name = options[:class_name]
class_name = name.to_s.camelize
class_name = class_name.singularize if [:has_many, :has_and_belongs_to_many].include?(macro)
end
active_record.send(:type_name_with_module, class_name)
end
end
end
end
end
|
