Add specific field error messages if email or password omitted

app/controllers/users/sessions_controller.rb

@@ -0,0 +1,16 @@
+class Users::SessionsController < Devise::SessionsController
+  def create
+    self.resource = resource_class.new
+    if params.dig("user", "email").empty?
+      resource.errors.add :email, "Please enter email address"
+    end
+    if params.dig("user", "password").empty?
+      resource.errors.add :password, "Please enter password"
+    end
+    if resource.errors.present?
+      render :new, status: :unprocessable_entity
+    else
+      super
+    end
+  end
+end

config/routes.rb

@@ -1,6 +1,6 @@
 Rails.application.routes.draw do
   devise_for :admin_users, ActiveAdmin::Devise.config
-  devise_for :users, controllers: { passwords: "users/passwords" }, skip: [:registrations]
+  devise_for :users, controllers: { passwords: "users/passwords", sessions: "users/sessions" }, skip: [:registrations]
   devise_scope :user do
     get "confirmations/reset", to: "users/passwords#reset_confirmation"
     get "users/edit" => "devise/registrations#edit", :as => "edit_user_registration"

spec/features/user_spec.rb

@@ -90,6 +90,14 @@ RSpec.describe "User Features" do
       expect(page).to have_selector("#error-summary-title")
       expect(page).to have_no_css(".govuk-notification-banner.govuk-notification-banner--success")
     end
+
+    it "show specific field error messages if a field was omitted" do
+      visit("/case_logs")
+      click_button("Sign in")
+      expect(page).to have_selector("#error-summary-title")
+      expect(page).to have_selector("#user-email-field-error")
+      expect(page).to have_selector("#user-password-field-error")
+    end
   end
 
   context "Your Account " do