从表单参数和属性Rails创建对象

class UsersController< ApplicationController
  def create
    @user = User.new(user_params)
    if @user.save
      redirect_to @user
    else
      render 'new'
    end
  end

  private

  def user_params
    params.require(:user).permit(:name, :email, :password)
  end
end

class User< ApplicationRecord
  validates :name, presence: true
  validates :email, presence: true, uniqueness: true
  validates :password, presence: true, length: { minimum: 6 }
end

<h1>Create a new user</h1>

<%= form_with(model: @user, local: true) do |form| %>
  <%= form.label :name %>
  <%= form.text_field :name %>

  <%= form.label :email %>
  <%= form.email_field :email %>

  <%= form.label :password %>
  <%= form.password_field :password %>

  <%= form.submit "Create" %>
<% end %>