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| 1 | +module Agents | |
| 2 | + class AttributeDifferenceAgent < Agent | |
| 3 | + cannot_be_scheduled! | |
| 4 | + | |
| 5 | + description <<-MD | |
| 6 | + The Attribute Difference Agent receives events and emits a new event with | |
| 7 | + the difference or change of a specific attribute in comparison to the previous | |
| 8 | + event received. | |
| 9 | + | |
| 10 | + `path` specifies the JSON path of the attribute to be used from the event. | |
| 11 | + | |
| 12 | + `output` specifies the new attribute name that will be created on the original payload | |
| 13 | + and it will contain the difference or change. | |
| 14 | + | |
| 15 | + `method` specifies if it should be... | |
| 16 | + | |
| 17 | + * `percentage_change` eg. Previous value was `160`, new value is `116`. Percentage change is `-27.5` | |
| 18 | + * `decimal_difference` eg. Previous value was `5.5`, new value is `15.2`. Difference is `9.7` | |
| 19 | + * `integer_difference` eg. Previous value was `50`, new value is `40`. Difference is `-10` | |
| 20 | + | |
| 21 | + `decimal_precision` defaults to `3`, but you can override this if you want. | |
| 22 | + | |
| 23 | + `expected_update_period_in_days` is used to determine if the Agent is working. | |
| 24 | + | |
| 25 | + The resulting event will be a copy of the received event with the difference | |
| 26 | + or change added as an extra attribute. If you use the `percentage_change` the | |
| 27 | +      attribute will be formatted as such `{{attribute}}_change`, otherwise it will | |
| 28 | +      be `{{attribute}}_diff`. | |
| 29 | + | |
| 30 | + All configuration options will be liquid interpolated based on the incoming event. | |
| 31 | + MD | |
| 32 | + | |
| 33 | + event_description <<-MD | |
| 34 | + This will change based on the source event. | |
| 35 | + MD | |
| 36 | + | |
| 37 | + def default_options | |
| 38 | +      { | |
| 39 | + 'path' => '.data.rate', | |
| 40 | + 'output' => 'rate_diff', | |
| 41 | + 'method' => 'integer_difference', | |
| 42 | + 'expected_update_period_in_days' => 1 | |
| 43 | + } | |
| 44 | + end | |
| 45 | + | |
| 46 | + def validate_options | |
| 47 | + unless options['path'].present? && options['method'].present? && options['output'].present? && options['expected_update_period_in_days'].present? | |
| 48 | + errors.add(:base, 'The attribute, method and expected_update_period_in_days fields are all required.') | |
| 49 | + end | |
| 50 | + end | |
| 51 | + | |
| 52 | + def working? | |
| 53 | + event_created_within?(interpolated['expected_update_period_in_days']) && !recent_error_logs? | |
| 54 | + end | |
| 55 | + | |
| 56 | + def receive(incoming_events) | |
| 57 | + incoming_events.each do |event| | |
| 58 | + handle(interpolated(event), event) | |
| 59 | + end | |
| 60 | + end | |
| 61 | + | |
| 62 | + private | |
| 63 | + | |
| 64 | + def handle(opts, event) | |
| 65 | + opts['decimal_precision'] ||= 3 | |
| 66 | + attribute_value = Utils.value_at(event.payload, opts['path']) | |
| 67 | + attribute_value = attribute_value.nil? ? 0 : attribute_value | |
| 68 | + payload = event.payload.deep_dup | |
| 69 | + | |
| 70 | + if opts['method'] == 'percentage_change' | |
| 71 | + change = calculate_percentage_change(attribute_value, opts['decimal_precision']) | |
| 72 | + payload[opts['output']] = change | |
| 73 | + | |
| 74 | + elsif opts['method'] == 'decimal_difference' | |
| 75 | + difference = calculate_decimal_difference(attribute_value, opts['decimal_precision']) | |
| 76 | + payload[opts['output']] = difference | |
| 77 | + | |
| 78 | + elsif opts['method'] == 'integer_difference' | |
| 79 | + difference = calculate_integer_difference(attribute_value) | |
| 80 | + payload[opts['output']] = difference | |
| 81 | + end | |
| 82 | + | |
| 83 | + created_event = create_event(payload: payload) | |
| 84 | +      log('Propagating new event', outbound_event: created_event, inbound_event: event) | |
| 85 | + update_memory(attribute_value) | |
| 86 | + end | |
| 87 | + | |
| 88 | + def calculate_integer_difference(new_value) | |
| 89 | + return 0 if last_value.nil? | |
| 90 | + (new_value.to_i - last_value.to_i) | |
| 91 | + end | |
| 92 | + | |
| 93 | + def calculate_decimal_difference(new_value, dec_pre) | |
| 94 | + return 0.0 if last_value.nil? | |
| 95 | + (new_value.to_f - last_value.to_f).round(dec_pre.to_i) | |
| 96 | + end | |
| 97 | + | |
| 98 | + def calculate_percentage_change(new_value, dec_pre) | |
| 99 | + return 0.0 if last_value.nil? | |
| 100 | + (((new_value.to_f / last_value.to_f) * 100) - 100).round(dec_pre.to_i) | |
| 101 | + end | |
| 102 | + | |
| 103 | + def last_value | |
| 104 | + memory['last_value'] | |
| 105 | + end | |
| 106 | + | |
| 107 | + def update_memory(new_value) | |
| 108 | + memory['last_value'] = new_value | |
| 109 | + end | |
| 110 | + end | |
| 111 | +end | 
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| 1 | +require 'rails_helper' | |
| 2 | + | |
| 3 | +describe Agents::AttributeDifferenceAgent do | |
| 4 | + def create_event(value=nil) | |
| 5 | + event = Event.new | |
| 6 | + event.agent = agents(:jane_weather_agent) | |
| 7 | +    event.payload = { | |
| 8 | + rate: value | |
| 9 | + } | |
| 10 | + event.save! | |
| 11 | + | |
| 12 | + event | |
| 13 | + end | |
| 14 | + | |
| 15 | + before do | |
| 16 | +    @valid_params = { | |
| 17 | + path: 'rate', | |
| 18 | + output: 'rate_diff', | |
| 19 | + method: 'integer_difference', | |
| 20 | + expected_update_period_in_days: '1' | |
| 21 | + } | |
| 22 | + | |
| 23 | + @checker = Agents::AttributeDifferenceAgent.new(name: 'somename', options: @valid_params) | |
| 24 | + @checker.user = users(:jane) | |
| 25 | + @checker.save! | |
| 26 | + end | |
| 27 | + | |
| 28 | + describe 'validation' do | |
| 29 | + before do | |
| 30 | + expect(@checker).to be_valid | |
| 31 | + end | |
| 32 | + | |
| 33 | + it 'should validate presence of output' do | |
| 34 | + @checker.options[:output] = nil | |
| 35 | + expect(@checker).not_to be_valid | |
| 36 | + end | |
| 37 | + | |
| 38 | + it 'should validate presence of path' do | |
| 39 | + @checker.options[:path] = nil | |
| 40 | + expect(@checker).not_to be_valid | |
| 41 | + end | |
| 42 | + | |
| 43 | + it 'should validate presence of method' do | |
| 44 | + @checker.options[:method] = nil | |
| 45 | + expect(@checker).not_to be_valid | |
| 46 | + end | |
| 47 | + | |
| 48 | + it 'should validate presence of expected_update_period_in_days' do | |
| 49 | + @checker.options[:expected_update_period_in_days] = nil | |
| 50 | + expect(@checker).not_to be_valid | |
| 51 | + end | |
| 52 | + end | |
| 53 | + | |
| 54 | + describe '#working?' do | |
| 55 | + before :each do | |
| 56 | + # Need to create an event otherwise event_created_within? returns nil | |
| 57 | + event = create_event | |
| 58 | + @checker.receive([event]) | |
| 59 | + end | |
| 60 | + | |
| 61 | + it 'is when event created within :expected_update_period_in_days' do | |
| 62 | + @checker.options[:expected_update_period_in_days] = 2 | |
| 63 | + expect(@checker).to be_working | |
| 64 | + end | |
| 65 | + | |
| 66 | + it 'isnt when event created outside :expected_update_period_in_days' do | |
| 67 | + @checker.options[:expected_update_period_in_days] = 2 | |
| 68 | + | |
| 69 | + time_travel_to 2.days.from_now do | |
| 70 | + expect(@checker).not_to be_working | |
| 71 | + end | |
| 72 | + end | |
| 73 | + end | |
| 74 | + | |
| 75 | + describe '#receive' do | |
| 76 | + before :each do | |
| 77 | +      @event = create_event('5.5') | |
| 78 | + end | |
| 79 | + | |
| 80 | + it 'creates events when memory is empty' do | |
| 81 | +      expect { | |
| 82 | + @checker.receive([@event]) | |
| 83 | + }.to change(Event, :count).by(1) | |
| 84 | + expect(Event.last.payload[:rate_diff]).to eq(0) | |
| 85 | + end | |
| 86 | + | |
| 87 | + it 'creates event with extra attribute for integer_difference' do | |
| 88 | + @checker.receive([@event]) | |
| 89 | +      event = create_event('6.5') | |
| 90 | + | |
| 91 | +      expect { | |
| 92 | + @checker.receive([event]) | |
| 93 | + }.to change(Event, :count).by(1) | |
| 94 | + expect(Event.last.payload[:rate_diff]).to eq(1) | |
| 95 | + end | |
| 96 | + | |
| 97 | + it 'creates event with extra attribute for decimal_difference' do | |
| 98 | + @checker.options[:method] = 'decimal_difference' | |
| 99 | + @checker.receive([@event]) | |
| 100 | +      event = create_event('6.4') | |
| 101 | + | |
| 102 | +      expect { | |
| 103 | + @checker.receive([event]) | |
| 104 | + }.to change(Event, :count).by(1) | |
| 105 | + expect(Event.last.payload[:rate_diff]).to eq(0.9) | |
| 106 | + end | |
| 107 | + | |
| 108 | + it 'creates event with extra attribute for percentage_change' do | |
| 109 | + @checker.options[:method] = 'percentage_change' | |
| 110 | + @checker.receive([@event]) | |
| 111 | +      event = create_event('9') | |
| 112 | + | |
| 113 | +      expect { | |
| 114 | + @checker.receive([event]) | |
| 115 | + }.to change(Event, :count).by(1) | |
| 116 | + expect(Event.last.payload[:rate_diff]).to eq(63.636) | |
| 117 | + end | |
| 118 | + | |
| 119 | + it 'creates event with extra attribute for percentage_change with the correct rounding' do | |
| 120 | + @checker.options[:method] = 'percentage_change' | |
| 121 | + @checker.options[:decimal_precision] = 5 | |
| 122 | + @checker.receive([@event]) | |
| 123 | +      event = create_event('9') | |
| 124 | + | |
| 125 | +      expect { | |
| 126 | + @checker.receive([event]) | |
| 127 | + }.to change(Event, :count).by(1) | |
| 128 | + expect(Event.last.payload[:rate_diff]).to eq(63.63636) | |
| 129 | + end | |
| 130 | + end | |
| 131 | +end |