Download inputs as a csv

app/controllers/api/v3/inputs_controller.rb

@@ -1,27 +1,31 @@
 # frozen_string_literal: true
+require 'csv'
 
 module Api
   module V3
     class InputsController < ::Api::V3::BaseController
       before_action do
         @scenario = Scenario.find(params[:scenario_id])
-        authorize!(:read, @scenario)
+        if user_signed_in? && current_user.can?(:read, @scenario)
+          authorize!(:read, @scenario)
+        end
       end
 
       # GET /api/v3/inputs
       # GET /api/v3/scenarios/:scenario_id/inputs
+      # GET /api/v3/scenarios/:scenario_id/inputs.csv
       #
-      # Returns the details for all available inputs. If the scenario_id isn't
-      # passed then the action will use the latest scenario.
-      #
+      # Returns input details in JSON or CSV format. Uses the latest scenario if
+      # scenario_id is not provided.
+
       def index
         extras = ActiveModel::Type::Boolean.new.cast(params[:include_extras])
+        inputs = serialized_inputs(extras)
 
-        render json: InputSerializer.collection(
-          Input.all,
-          @scenario,
-          **serializer_args(extra_attributes: extras)
-        )
+        respond_to do |format|
+          format.json { render json: inputs }
+          format.csv { send_csv_data(inputs) }
+        end
       end
 
       # GET /api/v3/inputs/:id
@@ -77,6 +81,55 @@ def serializer_args(extra_attributes:)
           extra_attributes:
         }
       end
+
+      def serialized_inputs(extras)
+        InputSerializer.collection(
+          Input.all,
+          @scenario,
+          **serializer_args(extra_attributes: extras)
+        )
+      end
+
+      def send_csv_data(inputs)
+        csv_data = generate_csv(inputs)
+        send_data csv_data, filename: "inputs_#{@scenario.id}.csv"
+      end
+
+      def generate_csv(inputs)
+        CSV.generate(headers: true) do |csv|
+          csv << csv_headers
+          cached_values = Input.cache(@scenario.parent)
+          user_values = @scenario.user_values
+          inputs.each do |key, input|
+            add_csv_row(csv, key, input, cached_values, user_values)
+          end
+        end
+      end
+
+      def csv_headers
+        ["Key", "Unit", "Start Year Value", "Scenario Value", "Min", "Max", "Share Group"]
+      end
+
+      def add_csv_row(csv, key, input, cached_values, user_values)
+        input_data = input.instance_variable_get(:@input)
+        return if input_data.nil?
+
+        puts(input.data.inspect)
+
+        # Provide a safe fallback for missing values
+        values = cached_values&.read(@scenario.parent, input_data) || {}
+        default_value = input.instance_variable_get(:@default_values_from)&.call(values) || ""
+
+        csv << [
+          key,
+          input_data.unit || "",
+          default_value || "",
+          user_values[input_data.key] || "",
+          input_data.min_value || "",
+          input_data.max_value || "",
+          input_data.share_group || ""
+        ]
+      end
     end
   end
 end

config/routes.rb

@@ -85,7 +85,7 @@
         get 'converters', to: redirect('/api/v3/scenarios/%{scenario_id}/nodes')
         get 'converters/:id', to: redirect('/api/v3/scenarios/%{scenario_id}/nodes/%{id}')
 
-        resources :inputs, :only => [:index, :show]
+        resources :inputs, only: [:index, :show], defaults: { format: :json }, constraints: { format: /(json|csv)/ }
 
         resource :version, :only => [:create, :show, :update], controller: 'scenario_version_tags'