如何使用Devise和Rails 3简单地验证用户名和密码是否正确

gem 'devise'

rails generate devise:install
rails generate devise User

rails db:migrate

class User < ApplicationRecord
  devise :database_authenticatable
end

Rails.application.routes.draw do
  devise_for :users
  # ...
end

<%= form_for(resource, as: resource_name, url: session_path(resource_name)) do |f| %>
  <div>
    <%= f.label :email %><br />
    <%= f.email_field :email, autofocus: true %>
  </div>

  <div>
    <%= f.label :password %><br />
    <%= f.password_field :password, autocomplete: "off" %>
  </div>

  <div>
    <%= f.submit "Log in" %>
  </div>
<% end %>

class SessionsController < ApplicationController
  def create
    user = User.find_by(email: params[:user][:email])
    if user && user.valid_password?(params[:user][:password])
      # 用户名和密码正确
      # 进行相应的操作
    else
      # 用户名或密码不正确
      # 处理错误情况
    end
  end
end