RoR scaffold在脚本/生成后添加字段

class User< ApplicationRecord
  validates :email, presence: true
end

class AddEmailToUsers< ActiveRecord::Migration[6.1]
  def change
    add_column :users, :email, :string
  end
end

<%= form_with(model: user, local: true) do |form| %>
  <%= form.label :email %>
  <%= form.text_field :email %>
  <%= form.submit %>
<% end %>

class User< ApplicationRecord
  validates :email, presence: true, uniqueness: true
end

def create
  @user = User.new(user_params)

  respond_to do |format|
    if @user.save
      format.html { redirect_to @user, notice: 'User was successfully created.' }
      format.json { render :show, status: :created, location: @user }
    else
      format.html { render :new, status: :unprocessable_entity }
      format.json { render json: @user.errors, status: :unprocessable_entity }
    end
  end
end

private
  def user_params
    params.require(:user).permit(:email)
  end

<p>
  <strong>Email:</strong>
  <%= @user.email %>
</p>