Provide endpoint to show a product group

Our Spree::Product corresponds to a DFC SuppliedProduct with variants.

engines/dfc_provider/app/controllers/dfc_provider/product_groups_controller.rb

@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+# Show Spree::Product as SuppliedProduct with variants.
+module DfcProvider
+  class ProductGroupsController < DfcProvider::ApplicationController
+    before_action :check_enterprise
+
+    def show
+      spree_product = current_enterprise.supplied_products.find(params[:id])
+      product = ProductGroupBuilder.product_group(spree_product)
+      render json: DfcIo.export(product)
+    end
+  end
+end

engines/dfc_provider/app/services/product_group_builder.rb

@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+class ProductGroupBuilder < DfcBuilder
+  def self.product_group(product)
+    id = urls.enterprise_product_group_url(
+      enterprise_id: product.variants.first.supplier_id,
+      id: product.id,
+    )
+    variants = product.variants.map do |spree_variant|
+      SuppliedProductBuilder.semantic_id(spree_variant)
+    end
+
+    DataFoodConsortium::Connector::SuppliedProduct.new(
+      id, variants:,
+    )
+  end
+end

engines/dfc_provider/app/services/supplied_product_builder.rb

@@ -1,11 +1,14 @@
 # frozen_string_literal: true
 
 class SuppliedProductBuilder < DfcBuilder
-  def self.supplied_product(variant)
-    id = urls.enterprise_supplied_product_url(
+  def self.semantic_id(variant)
+    urls.enterprise_supplied_product_url(
       enterprise_id: variant.supplier_id,
       id: variant.id,
     )
+  end
+
+  def self.supplied_product(variant)
     product_uri = urls.enterprise_url(
       variant.supplier_id,
       spree_product_id: variant.product_id
@@ -16,7 +19,7 @@ class SuppliedProductBuilder < DfcBuilder
     )
 
     DfcProvider::SuppliedProduct.new(
-      id,
+      semantic_id(variant),
       name: variant.product_and_full_name,
       description: variant.description,
       productType: product_type(variant),

engines/dfc_provider/spec/requests/product_groups_spec.rb

@@ -0,0 +1,49 @@
+# frozen_string_literal: true
+
+require_relative "../swagger_helper"
+
+RSpec.describe "ProductGroups", swagger_doc: "dfc.yaml", rswag_autodoc: true do
+  let!(:user) { create(:oidc_user) }
+  let!(:enterprise) { create(:distributor_enterprise, id: 10_000, owner: user) }
+  let!(:product) {
+    create(
+      :product_with_image,
+      id: 90_000,
+      name: "Pesto", description: "Basil Pesto",
+      variants: [variant]
+    )
+  }
+  let(:variant) {
+    build(:base_variant, id: 10_001, unit_value: 1, primary_taxon: taxon, supplier: enterprise)
+  }
+  let(:taxon) {
+    build(
+      :taxon,
+      name: "Processed Vegetable",
+      dfc_id: "https://github.com/datafoodconsortium/taxonomies/releases/latest/download/productTypes.rdf#processed-vegetable"
+    )
+  }
+
+  before { login_as user }
+
+  path "/api/dfc/enterprises/{enterprise_id}/product_groups/{id}" do
+    parameter name: :enterprise_id, in: :path, type: :string
+    parameter name: :id, in: :path, type: :string
+
+    let(:enterprise_id) { enterprise.id }
+
+    get "Show ProductGroup" do
+      produces "application/json"
+
+      response "200", "success" do
+        let(:id) { product.id }
+
+        run_test! do
+          expect(json_response["@id"]).to eq "http://test.host/api/dfc/enterprises/10000/product_groups/90000"
+
+          expect(json_response["dfc-b:hasVariant"]).to eq "http://test.host/api/dfc/enterprises/10000/supplied_products/10001"
+        end
+      end
+    end
+  end
+end

swagger/dfc.yaml

@@ -554,6 +554,34 @@ paths:
                     "@type": dfc-b:Person
         '404':
           description: not found
+  "/api/dfc/enterprises/{enterprise_id}/product_groups/{id}":
+    parameters:
+    - name: enterprise_id
+      in: path
+      required: true
+      schema:
+        type: string
+    - name: id
+      in: path
+      required: true
+      schema:
+        type: string
+    get:
+      summary: Show ProductGroup
+      tags:
+      - ProductGroups
+      responses:
+        '200':
+          description: success
+          content:
+            application/json:
+              examples:
+                test_example:
+                  value:
+                    "@context": https://www.datafoodconsortium.org
+                    "@id": http://test.host/api/dfc/enterprises/10000/product_groups/90000
+                    "@type": dfc-b:SuppliedProduct
+                    dfc-b:hasVariant: http://test.host/api/dfc/enterprises/10000/supplied_products/10001
   "/api/dfc/enterprises/{enterprise_id}/social_medias/{name}":
     get:
       summary: Show social media