feat(rounding): Expose rounding attributes to APIs (#2764)

## Context

In addition to the [flexible
aggregation](https://github.com/119ef63110d2803db639f0db37a3b135?pvs=25),
some customers wants to round the output of the aggregation.

## Description

This PR exposes `rounding_function` and `rounding_precision` fields to
REST and GraphQL APIs. It also update `BillableMetrics#CreateService`
and `BillableMetrics#UpdateService`

app/controllers/api/v1/billable_metrics_controller.rb

@@ -122,6 +122,8 @@ def input_params
           :recurring,
           :field_name,
           :expression,
+          :rounding_function,
+          :rounding_precision,
           filters: [:key, {values: []}]
         )
       end

app/graphql/types/billable_metrics/create_input.rb

@@ -12,6 +12,8 @@ class CreateInput < BaseInputObject
       argument :field_name, String, required: false
       argument :name, String, required: true
       argument :recurring, Boolean, required: false
+      argument :rounding_function, Types::BillableMetrics::RoundingFunctionEnum, required: false
+      argument :rounding_precision, Integer, required: false
       argument :weighted_interval, Types::BillableMetrics::WeightedIntervalEnum, required: false
 
       argument :filters, [Types::BillableMetricFilters::Input], required: false

app/graphql/types/billable_metrics/object.rb

@@ -27,6 +27,9 @@ class Object < Types::BaseObject
       field :recurring, Boolean, null: false
       field :subscriptions_count, Integer, null: false
 
+      field :rounding_function, Types::BillableMetrics::RoundingFunctionEnum, null: true
+      field :rounding_precision, Integer, null: true
+
       field :created_at, GraphQL::Types::ISO8601DateTime, null: false
       field :deleted_at, GraphQL::Types::ISO8601DateTime, null: true
       field :updated_at, GraphQL::Types::ISO8601DateTime, null: false

app/graphql/types/billable_metrics/rounding_function_enum.rb

@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+module Types
+  module BillableMetrics
+    class RoundingFunctionEnum < Types::BaseEnum
+      BillableMetric::ROUNDING_FUNCTIONS.values.each do |type|
+        value type
+      end
+    end
+  end
+end

app/graphql/types/billable_metrics/update_input.rb

@@ -14,6 +14,8 @@ class UpdateInput < BaseInputObject
       argument :field_name, String, required: false
       argument :name, String, required: true
       argument :recurring, Boolean, required: false
+      argument :rounding_function, Types::BillableMetrics::RoundingFunctionEnum, required: false
+      argument :rounding_precision, Integer, required: false
       argument :weighted_interval, Types::BillableMetrics::WeightedIntervalEnum, required: false
 
       argument :filters, [Types::BillableMetricFilters::Input], required: false

app/serializers/v1/billable_metric_serializer.rb

@@ -11,6 +11,8 @@ def serialize
         aggregation_type: model.aggregation_type,
         weighted_interval: model.weighted_interval,
         recurring: model.recurring,
+        rounding_function: model.rounding_function,
+        rounding_precision: model.rounding_precision,
         created_at: model.created_at.iso8601,
         field_name: model.field_name,
         expression: model.expression,

app/services/billable_metrics/create_service.rb

@@ -23,6 +23,8 @@ def call
           recurring: args[:recurring] || false,
           aggregation_type: args[:aggregation_type]&.to_sym,
           field_name: args[:field_name],
+          rounding_function: args[:rounding_function]&.to_sym,
+          rounding_precision: args[:rounding_precision],
           weighted_interval: args[:weighted_interval]&.to_sym,
           expression: args[:expression]
         )

app/services/billable_metrics/update_service.rb

@@ -38,6 +38,8 @@ def call
         billable_metric.weighted_interval = params[:weighted_interval]&.to_sym if params.key?(:weighted_interval)
         billable_metric.field_name = params[:field_name] if params.key?(:field_name)
         billable_metric.recurring = params[:recurring] if params.key?(:recurring)
+        billable_metric.rounding_function = params[:rounding_function] if params.key?(:rounding_function)
+        billable_metric.rounding_precision = params[:rounding_precision] if params.key?(:rounding_precision)
         billable_metric.weighted_interval = params[:weighted_interval]&.to_sym if params.key?(:weighted_interval)
         billable_metric.expression = params[:expression] if params.key?(:expression)
 

spec/graphql/types/billable_metrics/create_input_spec.rb

@@ -12,6 +12,8 @@
   it { is_expected.to accept_argument(:field_name).of_type('String') }
   it { is_expected.to accept_argument(:name).of_type('String!') }
   it { is_expected.to accept_argument(:recurring).of_type('Boolean') }
+  it { is_expected.to accept_argument(:rounding_function).of_type('RoundingFunctionEnum') }
+  it { is_expected.to accept_argument(:rounding_precision).of_type('Int') }
   it { is_expected.to accept_argument(:weighted_interval).of_type('WeightedIntervalEnum') }
   it { is_expected.to accept_argument(:filters).of_type('[BillableMetricFiltersInput!]') }
 end

spec/graphql/types/billable_metrics/object_spec.rb

@@ -24,4 +24,6 @@
   it { is_expected.to have_field(:deleted_at).of_type('ISO8601DateTime') }
   it { is_expected.to have_field(:updated_at).of_type('ISO8601DateTime!') }
   it { is_expected.to have_field(:integration_mappings).of_type('[Mapping!]') }
+  it { is_expected.to have_field(:rounding_function).of_type('RoundingFunctionEnum') }
+  it { is_expected.to have_field(:rounding_precision).of_type('Int') }
 end

spec/graphql/types/billable_metrics/update_input_spec.rb

@@ -13,6 +13,8 @@
   it { is_expected.to accept_argument(:field_name).of_type('String') }
   it { is_expected.to accept_argument(:name).of_type('String!') }
   it { is_expected.to accept_argument(:recurring).of_type('Boolean') }
+  it { is_expected.to accept_argument(:rounding_function).of_type('RoundingFunctionEnum') }
+  it { is_expected.to accept_argument(:rounding_precision).of_type('Int') }
   it { is_expected.to accept_argument(:weighted_interval).of_type('WeightedIntervalEnum') }
   it { is_expected.to accept_argument(:filters).of_type('[BillableMetricFiltersInput!]') }
 end

spec/requests/api/v1/billable_metrics_controller_spec.rb

@@ -14,7 +14,9 @@
         aggregation_type: 'sum_agg',
         field_name: 'amount_sum',
         expression: '1 + 2',
-        recurring: true
+        recurring: true,
+        rounding_function: 'round',
+        rounding_precision: 2
       }
     end
 
@@ -28,6 +30,8 @@
       expect(json[:billable_metric][:created_at]).to be_present
       expect(json[:billable_metric][:recurring]).to eq(create_params[:recurring])
       expect(json[:billable_metric][:expression]).to eq(create_params[:expression])
+      expect(json[:billable_metric][:rounding_function]).to eq(create_params[:rounding_function])
+      expect(json[:billable_metric][:rounding_precision]).to eq(create_params[:rounding_precision])
       expect(json[:billable_metric][:filters]).to eq([])
     end
 
@@ -49,10 +53,7 @@
 
         expect(response).to have_http_status(:success)
         expect(json[:billable_metric][:lago_id]).to be_present
-        expect(json[:billable_metric][:recurring]).to eq(
-          create_params[:recurring
-                    ]
-        )
+        expect(json[:billable_metric][:recurring]).to eq(create_params[:recurring])
         expect(json[:billable_metric][:aggregation_type]).to eq('weighted_sum_agg')
         expect(json[:billable_metric][:weighted_interval]).to eq('seconds')
       end

spec/serializers/v1/billable_metric_serializer_spec.rb

@@ -17,6 +17,8 @@
       expect(result['billable_metric']['aggregation_type']).to eq(billable_metric.aggregation_type)
       expect(result['billable_metric']['field_name']).to eq(billable_metric.field_name)
       expect(result['billable_metric']['created_at']).to eq(billable_metric.created_at.iso8601)
+      expect(result['billable_metric']['rounding_function']).to eq(billable_metric.rounding_function)
+      expect(result['billable_metric']['rounding_precision']).to eq(billable_metric.rounding_precision)
       expect(result['billable_metric']['weighted_interval']).to eq(billable_metric.weighted_interval)
       expect(result['billable_metric']['expression']).to eq(billable_metric.expression)
       expect(result['billable_metric']['active_subscriptions_count']).to eq(0)

spec/services/billable_metrics/create_service_spec.rb

@@ -21,6 +21,8 @@
         organization_id: organization.id,
         aggregation_type: "count_agg",
         expression: "1 + 2",
+        rounding_function: "ceil",
+        rounding_precision: 2,
         recurring: false
       }
     end

spec/services/billable_metrics/update_service_spec.rb

@@ -16,27 +16,30 @@
       description: 'New metric description',
       aggregation_type: 'sum_agg',
       field_name: 'field_value',
-      expression: '1 + 3'
+      expression: '1 + 3',
+      rounding_function: 'ceil',
+      rounding_precision: 2
     }.tap do |p|
       p[:filters] = filters unless filters.nil?
     end
   end
   let(:filters) { nil }
 
   describe '#call' do
-    it 'updates the billable metric' do
+    it 'updates the billable metric', aggregate_failures: true do
       result = update_service.call
-
-      aggregate_failures do
-        expect(result).to be_success
-
-        metric = result.billable_metric
-        expect(metric.id).to eq(billable_metric.id)
-        expect(metric.name).to eq('New Metric')
-        expect(metric.code).to eq('new_metric')
-        expect(metric.aggregation_type).to eq('sum_agg')
-        expect(metric.expression).to eq('1 + 3')
-      end
+      expect(result).to be_success
+
+      metric = result.billable_metric
+      expect(metric).to have_attributes(
+        id: billable_metric.id,
+        name: 'New Metric',
+        code: 'new_metric',
+        aggregation_type: 'sum_agg',
+        rounding_function: 'ceil',
+        rounding_precision: 2,
+        expression: '1 + 3'
+      )
     end
 
     context 'with filters arguments' do
@@ -106,7 +109,7 @@
 
       before { charge }
 
-      it 'updates only name and description' do
+      it 'updates only name and description', aggregate_failures: true do
         result = update_service.call
 
         aggregate_failures do
@@ -120,7 +123,9 @@
           expect(result.billable_metric).not_to have_attributes(
             code: 'new_metric',
             aggregation_type: 'sum_agg',
-            field_name: 'field_value'
+            field_name: 'field_value',
+            rounding_function: 'ceil',
+            rounding_precision: 2
           )
         end
       end