aboutsummaryrefslogtreecommitdiffstats
path: root/activemodel/lib/active_model/callbacks.rb
blob: 15103f11856df89b2d2978495026ad417bdf66e1 (plain) (blame)
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
require 'active_support/core_ext/array/wrap'
require 'active_support/callbacks'

module ActiveModel
  # == Active Model Callbacks
  #
  # Provides an interface for any class to have Active Record like callbacks.
  #
  # Like the Active Record methods, the callback chain is aborted as soon as
  # one of the methods in the chain returns false.
  #
  # First, extend ActiveModel::Callbacks from the class you are creating:
  #
  #   class MyModel
  #     extend ActiveModel::Callbacks
  #   end
  #
  # Then define a list of methods that you want callbacks attached to:
  #
  #   define_model_callbacks :create, :update
  #
  # This will provide all three standard callbacks (before, around and after) for
  # both the :create and :update methods. To implement, you need to wrap the methods
  # you want callbacks on in a block so that the callbacks get a chance to fire:
  #
  #   def create
  #     run_callbacks :create do
  #       # Your create action methods here
  #     end
  #   end
  #
  # Then in your class, you can use the +before_create+, +after_create+ and +around_create+
  # methods, just as you would in an Active Record module.
  #
  #   before_create :action_before_create
  #
  #   def action_before_create
  #     # Your code here
  #   end
  #
  # You can choose not to have all three callbacks by passing a hash to the
  # define_model_callbacks method.
  #
  #   define_model_callbacks :create, :only => [:after, :before]
  #
  # Would only create the after_create and before_create callback methods in your
  # class.
  module Callbacks
    def self.extended(base)
      base.class_eval do
        include ActiveSupport::Callbacks
      end
    end

    # define_model_callbacks accepts the same options define_callbacks does, in case
    # you want to overwrite a default. Besides that, it also accepts an :only option,
    # where you can choose if you want all types (before, around or after) or just some.
    #
    #   define_model_callbacks :initializer, :only => :after
    #
    # Note, the <tt>:only => <type></tt> hash will apply to all callbacks defined on
    # that method call. To get around this you can call the define_model_callbacks
    # method as many times as you need.
    #
    #   define_model_callbacks :create, :only => :after
    #   define_model_callbacks :update, :only => :before
    #   define_model_callbacks :destroy, :only => :around
    #
    # Would create +after_create+, +before_update+ and +around_destroy+ methods only.
    #
    # You can pass in a class to before_<type>, after_<type> and around_<type>, in which
    # case the callback will call that class's <action>_<type> method passing the object
    # that the callback is being called on.
    #
    #   class MyModel
    #     extend ActiveModel::Callbacks
    #     define_model_callbacks :create
    #
    #     before_create AnotherClass
    #   end
    #
    #   class AnotherClass
    #     def self.before_create( obj )
    #       # obj is the MyModel instance that the callback is being called on
    #     end
    #   end
    #
    def define_model_callbacks(*callbacks)
      options = callbacks.extract_options!
      options = {
         :terminator => "result == false",
         :scope => [:kind, :name],
         :only => [:before, :around, :after]
      }.merge(options)

      types = Array.wrap(options.delete(:only))

      callbacks.each do |callback|
        define_callbacks(callback, options)

        types.each do |type|
          send("_define_#{type}_model_callback", self, callback)
        end
      end
    end

    def _define_before_model_callback(klass, callback) #:nodoc:
      klass.class_eval <<-CALLBACK, __FILE__, __LINE__ + 1
        def self.before_#{callback}(*args, &block)
          set_callback(:#{callback}, :before, *args, &block)
        end
      CALLBACK
    end

    def _define_around_model_callback(klass, callback) #:nodoc:
      klass.class_eval <<-CALLBACK, __FILE__, __LINE__ + 1
        def self.around_#{callback}(*args, &block)
          set_callback(:#{callback}, :around, *args, &block)
        end
      CALLBACK
    end

    def _define_after_model_callback(klass, callback) #:nodoc:
      klass.class_eval <<-CALLBACK, __FILE__, __LINE__ + 1
        def self.after_#{callback}(*args, &block)
          options = args.extract_options!
          options[:prepend] = true
          options[:if] = Array.wrap(options[:if]) << "!halted && value != false"
          set_callback(:#{callback}, :after, *(args << options), &block)
        end
      CALLBACK
    end
  end
end