Add API endpoint to get the group for a form

app/controllers/api/form_documents_controller.rb

@@ -3,6 +3,10 @@ def show
     render json: form_document.content
   end
 
+  def group
+    render json: Form.find_by!(id: form_id).group
+  end
+
 private
 
   def form_document
@@ -17,4 +21,8 @@ def form_document_params
 
     permitted_params
   end
+
+  def form_id
+    params.require(:form_id)
+  end
 end

app/models/group.rb

@@ -34,9 +34,19 @@ def to_param
     external_id
   end
 
+  def as_json(options = {})
+    options[:only] ||= %i[name external_id]
+    options[:methods] ||= %i[group_admin_users organisation]
+    super(options)
+  end
+
 private
 
   def set_external_id
     self.external_id = ExternalIdProvider.generate_unique_id_for(Group)
   end
+
+  def group_admin_users
+    users.group_admins
+  end
 end

app/models/organisation.rb

@@ -20,4 +20,12 @@ def name_with_abbreviation
   def admin_users
     users.organisation_admin
   end
+
+  alias_method :organisation_admin_users, :admin_users
+
+  def as_json(options = {})
+    options[:only] ||= %i[id name]
+    options[:methods] ||= %i[organisation_admin_users]
+    super(options)
+  end
 end

app/models/user.rb

@@ -159,6 +159,11 @@ def signed_in!
     update!(last_signed_in_at: Time.zone.now)
   end
 
+  def as_json(options = {})
+    options[:only] ||= %i[name email]
+    super(options)
+  end
+
 private
 
   def requires_name?

config/routes.rb

@@ -272,6 +272,7 @@
   scope "api/v2", as: "api_v2" do
     scope "forms/:form_id" do
       get "/:tag", to: "api/form_documents#show", as: :form_document, constraints: { tag: /draft|live|archived/ }
+      get "/group", to: "api/form_documents#group", as: :form_group
     end
   end
 

spec/requests/api/form_documents_controller_spec.rb

@@ -3,7 +3,7 @@
 RSpec.describe Api::FormDocumentsController, type: :request do
   let(:headers) { { "ACCEPT": "application/json" } }
 
-  describe "GET /show" do
+  describe "#show" do
     context "when the form exists" do
       context "when the tag is draft" do
         let(:draft_form_name) { "Draft form" }
@@ -151,6 +151,51 @@
     end
   end
 
+  describe "#group" do
+    context "when the form exists" do
+      let(:form) { create(:form) }
+      let(:group) { create(:group, organisation: test_org) }
+      let(:group_admin) { create(:user) }
+
+      before do
+        organisation_admin_user
+        create(:membership, user: group_admin, group:, role: :group_admin)
+        create(:membership, user: create(:user), group:, role: :editor)
+
+        group.group_forms.create!(form_id: form.id)
+      end
+
+      it "returns the group" do
+        get("/api/v2/forms/#{form.id}/group", headers:)
+
+        expect(response).to have_http_status(:success)
+        expect(response.parsed_body).to eq({
+          "external_id" => group.external_id,
+          "name" => group.name,
+          "group_admin_users" => [
+            { "name" => group_admin.name, "email" => group_admin.email },
+          ],
+          "organisation" => {
+            "id" => test_org.id,
+            "name" => test_org.name,
+            "organisation_admin_users" => [
+              { "name" => organisation_admin_user.name, "email" => organisation_admin_user.email },
+            ],
+          },
+        })
+      end
+    end
+
+    context "when the form doesn't exist" do
+      it "returns http not found" do
+        get("/api/v2/forms/non-existent/group", headers:)
+
+        expect(response).to have_http_status(:not_found)
+        expect(response.headers["Content-Type"]).to eq("application/json; charset=utf-8")
+      end
+    end
+  end
+
   describe "logging", :capture_logging do
     let(:trace_id) { "Root=1-63441c4a-abcdef012345678912345678" }
     let(:request_id) { "a-request-id" }