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
|
require 'active_support/hash_with_indifferent_access'
require 'active_support/core_ext/object/duplicable'
module ActiveModel
# == Active \Model \Dirty
#
# Provides a way to track changes in your object in the same way as
# Active Record does.
#
# The requirements for implementing ActiveModel::Dirty are:
#
# * <tt>include ActiveModel::Dirty</tt> in your object.
# * Call <tt>define_attribute_methods</tt> passing each method you want to
# track.
# * Call <tt>attr_name_will_change!</tt> before each change to the tracked
# attribute.
# * Call <tt>changes_applied</tt> after the changes are persisted.
# * Call <tt>reset_changes</tt> when you want to reset the changes
# information.
#
# A minimal implementation could be:
#
# class Person
# include ActiveModel::Dirty
#
# define_attribute_methods :name
#
# def name
# @name
# end
#
# def name=(val)
# name_will_change! unless val == @name
# @name = val
# end
#
# def save
# # do persistence work
# changes_applied
# end
#
# def reload!
# reset_changes
# end
# end
#
# A newly instantiated object is unchanged:
#
# person = Person.find_by(name: 'Uncle Bob')
# person.changed? # => false
#
# Change the name:
#
# person.name = 'Bob'
# person.changed? # => true
# person.name_changed? # => true
# person.name_was # => "Uncle Bob"
# person.name_change # => ["Uncle Bob", "Bob"]
# person.name = 'Bill'
# person.name_change # => ["Uncle Bob", "Bill"]
#
# Save the changes:
#
# person.save
# person.changed? # => false
# person.name_changed? # => false
#
# Reset the changes:
#
# person.previous_changes # => {"name" => ["Uncle Bob", "Bill"]}
# person.reload!
# person.previous_changes # => {}
#
# Assigning the same value leaves the attribute unchanged:
#
# person.name = 'Bill'
# person.name_changed? # => false
# person.name_change # => nil
#
# Which attributes have changed?
#
# person.name = 'Bob'
# person.changed # => ["name"]
# person.changes # => {"name" => ["Bill", "Bob"]}
#
# If an attribute is modified in-place then make use of <tt>[attribute_name]_will_change!</tt>
# to mark that the attribute is changing. Otherwise ActiveModel can't track
# changes to in-place attributes.
#
# person.name_will_change!
# person.name_change # => ["Bill", "Bill"]
# person.name << 'y'
# person.name_change # => ["Bill", "Billy"]
module Dirty
extend ActiveSupport::Concern
include ActiveModel::AttributeMethods
included do
attribute_method_suffix '_changed?', '_change', '_will_change!', '_was'
attribute_method_affix prefix: 'reset_', suffix: '!'
end
# Returns +true+ if any attribute have unsaved changes, +false+ otherwise.
#
# person.changed? # => false
# person.name = 'bob'
# person.changed? # => true
def changed?
changed_attributes.present?
end
# Returns an array with the name of the attributes with unsaved changes.
#
# person.changed # => []
# person.name = 'bob'
# person.changed # => ["name"]
def changed
changed_attributes.keys
end
# Returns a hash of changed attributes indicating their original
# and new values like <tt>attr => [original value, new value]</tt>.
#
# person.changes # => {}
# person.name = 'bob'
# person.changes # => { "name" => ["bill", "bob"] }
def changes
ActiveSupport::HashWithIndifferentAccess[changed.map { |attr| [attr, attribute_change(attr)] }]
end
# Returns a hash of attributes that were changed before the model was saved.
#
# person.name # => "bob"
# person.name = 'robert'
# person.save
# person.previous_changes # => {"name" => ["bob", "robert"]}
def previous_changes
@previously_changed ||= {}
end
# Returns a hash of the attributes with unsaved changes indicating their original
# values like <tt>attr => original value</tt>.
#
# person.name # => "bob"
# person.name = 'robert'
# person.changed_attributes # => {"name" => "bob"}
def changed_attributes
@changed_attributes ||= {}
end
# Handle <tt>*_changed?</tt> for +method_missing+.
def attribute_changed?(attr)
changed_attributes.include?(attr)
end
# Handle <tt>*_was</tt> for +method_missing+.
def attribute_was(attr)
attribute_changed?(attr) ? changed_attributes[attr] : __send__(attr)
end
private
# Removes current changes and makes them accessible through +previous_changes+.
def changes_applied
@previously_changed = changes
@changed_attributes = {}
end
# Removes all dirty data: current changes and previous changes
def reset_changes
@previously_changed = {}
@changed_attributes = {}
end
# Handle <tt>*_change</tt> for +method_missing+.
def attribute_change(attr)
[changed_attributes[attr], __send__(attr)] if attribute_changed?(attr)
end
# Handle <tt>*_will_change!</tt> for +method_missing+.
def attribute_will_change!(attr)
return if attribute_changed?(attr)
begin
value = __send__(attr)
value = value.duplicable? ? value.clone : value
rescue TypeError, NoMethodError
end
changed_attributes[attr] = value
end
# Handle <tt>reset_*!</tt> for +method_missing+.
def reset_attribute!(attr)
if attribute_changed?(attr)
__send__("#{attr}=", changed_attributes[attr])
changed_attributes.delete(attr)
end
end
end
end
|