summaryrefslogtreecommitdiff
path: root/lib/bulk_imports/pipeline.rb
blob: 1444516273798685bc6ae3a855ee4072d5e42d02 (plain)
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
# frozen_string_literal: true

module BulkImports
  module Pipeline
    extend ActiveSupport::Concern
    include Gitlab::Utils::StrongMemoize
    include Gitlab::ClassAttributes
    include Runner

    NotAllowedError = Class.new(StandardError)

    CACHE_KEY_EXPIRATION = 2.hours

    def initialize(context)
      @context = context
    end

    included do
      private

      attr_reader :context

      # Fetch pipeline extractor.
      # An extractor is defined either by instance `#extract(context)` method
      # or by using `extractor` DSL.
      #
      # @example
      # class MyPipeline
      #   extractor MyExtractor, foo: :bar
      # end
      #
      # class MyPipeline
      #   def extract(context)
      #     puts 'Fetch some data'
      #   end
      # end
      #
      # If pipeline implements instance method `extract` - use it
      # and ignore class `extractor` method implementation.
      def extractor
        @extractor ||= self.respond_to?(:extract) ? self : instantiate(self.class.get_extractor)
      end

      # Fetch pipeline transformers.
      #
      # A transformer can be defined using:
      #   - `transformer` class method
      #   - `transform` instance method
      #
      # Multiple transformers can be defined within a single
      # pipeline and run sequentially for each record in the
      # following order:
      #   - Transformers defined using `transformer` class method
      #   - Instance method `transform`
      #
      # Instance method `transform` is always the last to run.
      #
      # @example
      # class MyPipeline
      #   transformer MyTransformerOne, foo: :bar
      #   transformer MyTransformerTwo, foo: :bar
      #
      #   def transform(context, data)
      #     # perform transformation here
      #   end
      # end
      #
      # In the example above `#transform` is the first to run and
      # `MyTransformerTwo` method is the last.
      def transformers
        strong_memoize(:transformers) do
          defined_transformers = self.class.transformers.map(&method(:instantiate))

          transformers = []
          transformers << self if respond_to?(:transform)
          transformers.concat(defined_transformers)
          transformers
        end
      end

      # Fetch pipeline loader.
      # A loader is defined either by instance method `#load(context, data)`
      # or by using `loader` DSL.
      #
      # @example
      # class MyPipeline
      #   loader MyLoader, foo: :bar
      # end
      #
      # class MyPipeline
      #   def load(context, data)
      #     puts 'Load some data'
      #   end
      # end
      #
      # If pipeline implements instance method `load` - use it
      # and ignore class `loader` method implementation.
      def loader
        @loader ||= self.respond_to?(:load) ? self : instantiate(self.class.get_loader)
      end

      def pipeline
        @pipeline ||= self.class.name
      end

      def instantiate(class_config)
        options = class_config[:options]

        if options
          class_config[:klass].new(class_config[:options])
        else
          class_config[:klass].new
        end
      end

      def abort_on_failure?
        self.class.abort_on_failure?
      end
    end

    class_methods do
      def extractor(klass, options = nil)
        class_attributes[:extractor] = { klass: klass, options: options }
      end

      def transformer(klass, options = nil)
        add_attribute(:transformers, klass, options)
      end

      def loader(klass, options = nil)
        class_attributes[:loader] = { klass: klass, options: options }
      end

      def get_extractor
        class_attributes[:extractor]
      end

      def transformers
        class_attributes[:transformers] || []
      end

      def get_loader
        class_attributes[:loader]
      end

      def abort_on_failure!
        class_attributes[:abort_on_failure] = true
      end

      def abort_on_failure?
        class_attributes[:abort_on_failure]
      end

      private

      def add_attribute(sym, klass, options)
        class_attributes[sym] ||= []
        class_attributes[sym] << { klass: klass, options: options }
      end
    end
  end
end