app/controllers/guests_controller.rb

@@ -11,12 +11,12 @@ class GuestsController < ApplicationController
   end
 
   def create
-    Guest.create!(params.require(:guest).permit(:name, :group_id, :status))
+    Guest.create!(guest_params)
     render json: {}, status: :created
   end
 
   def update
-    Guest.find(params[:id]).update!(params.require(:guest).permit(:name, :status))
+    Guest.find(params[:id]).update!(guest_params)
     render json: {}, status: :ok
   end
 
@@ -24,4 +24,10 @@ class GuestsController < ApplicationController
     Guest.find(params[:id]).destroy!
     render json: {}, status: :ok
   end
+
+  private
+
+  def guest_params
+    params.require(:guest).permit(:name, :group_id, :status)
+  end
 end

spec/requests/guests_spec.rb

@@ -67,6 +67,7 @@ RSpec.describe 'guests', type: :request do
             type: :object,
             properties: {
               name: { type: :string },
+              group_id: { type: :string, format: :uuid },
               status: { type: :string, enum: Guest.statuses.keys }
             }
           }