user validation

app/controllers/application_controller.rb

@@ -1,10 +1,19 @@
 class ApplicationController < ActionController::Base
   helper_method :current_user
   helper_method :logged_in?
+
   def current_user
     User.find_by(id: session[:user_id])
   end
+  
   def logged_in?
     !current_user.nil?
   end
+
+  def notices_from_errors(record)
+    messages = record.errors.messages.map do |attribute, messages|
+      messages.map { |message| "#{attribute} #{message}".capitalize }
+    end
+    messages.flatten
+  end
 end

app/controllers/users_controller.rb

@@ -5,8 +5,12 @@ class UsersController < ApplicationController
 
   def create
     @user = User.create(params.require(:user).permit(:email, :password))
-    session[:user_id] = @user.id
-    redirect_to '/welcome', notice: 'Account has been created'
+    if @user.invalid?
+      redirect_to '/welcome', notice: notices_from_errors(@user)
+    else
+      session[:user_id] = @user.id
+      redirect_to '/welcome', notice: 'Account has been created'
+    end
   end
 
   def password_recovery_request