undefined method `name' for nil:NilClassの原因と解決策

前提・実現したいこと

NoMethodError in UsersController#create
undefined method `name' for #User:0x00007fcd02e976a0
のエラーが出ていて、詰まっています。ご教示お願い致します。

first_name と　last_nameを追加し、migrationファイルを作成、データベースに変更を加えた直後
上記のエラーが出てしまいました。

発生している問題・エラーメッセージ

エラーメッセージ

usercontrollerrb
1class UsersController < ApplicationController
2  def new
3    @user = User.new
4  end
5
6  def show
7    @user = User.find(params[:id])
8  end
9
10  def create
11    @user = User.new(user_params)
12     
13    if @user.save
14      log_in @user
15      flash[:success] = "Signup success!"
16      redirect_to @user
17    else
18      render :new
19    end
20  end
21
22  private
23
24  def user_params
25    params.require(:user).permit(:first_name,:last_name, :email, :password,
26                                 :password_confirmation)
27  end
28end

newhtmlerb
1<% provide(:title, 'Sign up') %>
2<h1>Sign up</h1>
3
4<div class="row">
5  <div class="col-md-6 col-md-offset-3">
6  
7    <%= form_with(model: @user, local: true) do |f| %>
8      <%= render 'shared/error_messages' %>
9
10      <%= f.label :first_name  %>
11      <%= f.text_field :first_name, class: 'form-control' %>
12      <%= f.label :last_name %>
13      <%= f.text_field :last_name, class: 'form-control' %>
14
15      <%= f.label :email %>
16      <%= f.email_field :email, class: 'form-control' %>
17
18      <%= f.label :password %>
19      <%= f.password_field :password, class: 'form-control' %>
20
21      <%= f.label :password_confirmation, "Confirmation" %>
22      <%= f.password_field :password_confirmation, class: 'form-control' %>
23
24      <%= f.submit "Create my account", class: "btn btn-primary" %>
25    <% end %>
26  </div>
27</div>
28

schemarb
1ActiveRecord::Schema.define(version: 2021_05_23_022437) do
2
3  create_table "users", force: :cascade do |t|
4    t.string "first_name"
5    t.string "email"
6    t.datetime "created_at", precision: 6, null: false
7    t.datetime "updated_at", precision: 6, null: false
8    t.string "password_digest"
9    t.string "last_name"
10  end
11
12end

class AddFirstNameToUsers < ActiveRecord::Migration[6.0]
  def change
    rename_column :users, :name, :first_name
  end
end

class AddLastNameToUsers < ActiveRecord::Migration[6.0]
  def change
    add_column :users, :last_name, :string
  end
end

userrb
1class User < ApplicationRecord
2  before_save { self.email = email.downcase }
3
4  VALID_EMAIL_REGEX = /\A[\w+\-.]+@[a-z\d\-.]+.[a-z]+\z/i
5  validates :name,  presence: true, length: { maximum: 50 }
6  validates :email, presence: true, length: { maximum: 255 },
7                    format: { with: VALID_EMAIL_REGEX },
8                    uniqueness: true
9  validates :password, presence: true, length: { minimum: 6 }
10  has_secure_password
11
12  # Returns the hash digest of the given string.
13  def User.digest(string)
14    cost = ActiveModel::SecurePassword.min_cost ? BCrypt::Engine::MIN_COST :
15                                                  BCrypt::Engine.cost
16    BCrypt::Password.create(string, cost: cost)
17  end
18end
19