如果 Session 不是 Active Record 模型，如何处理 :session 错误？

没有会话模型。除了显示一般失败通知之外，如何创建有关表单提交失败原因的特定错误？

回想一下第 7.3.3 节，我们使用用户模型错误消息显示注册错误。这些错误与特定的 Active Record 对象相关，但此策略在这里不起作用，因为会话不是 Active Record 模型。相反，我们将在闪存中放置一条消息，以便在登录失败时显示。导轨教程 https://www.railstutorial.org/book/basic_login

控制器

class SessionsController < ApplicationController

  def new
  end

   def create
    user = User.find_by(email: params[:session][:email].downcase)
    if user && user.authenticate(params[:session][:password])
      if user.activated?
        log_in user
        params[:session][:remember_me] == '1' ? remember(user) : forget(user)
        redirect_back_or user
      else
        message  = "Account not activated. "
        message += "Check your email for the activation link."
        flash[:warning] = message
        redirect_to root_url
      end
    else
      flash.now[:danger] = 'Invalid email/password combination'
      render 'new'
    end
  end

Form

<%= form_for(:session, url: login_path) do |f| %>
  <%= f.label :email %>
  <%= f.email_field :email, class: 'form-control' %>
  <%= f.label :password %>
  <%= f.password_field :password, class: 'form-control' %>
  <%= f.submit "Sign in", class: "btn btn-primary sessions" %>
<% end %>

参数传递如下：

于 2016-09-06 17:33:59 +0000 于 68.204.49.62 开始发布“/login” 2016-09-06T17：33：59.165393 + 00：00应用程序[web.1]：参数：{“utf8”=>“✓”，“authenticity_token”=>“DhKuJCjbeVgBOsQiujgd34540Vk3i5ouRFpAm8JnU9ZKWlMZhxN7VPnWJrfuuKmg FNTvsDfJNTXNLRpI1pHNebA==", "会话"=>{"电子邮件“=>”[电子邮件受保护] /cdn-cgi/l/email-protection", "密码"=>"[已过滤]", "remember_me"=>"0"}, "提交"=>"登录"}

编辑：所以我想到这样做？

def create
    user = User.find_by(email: params[:session][:email].downcase)
    if user 
      if user.authenticate(params[:session][:password])
        if user.activated?
          log_in user
          params[:session][:remember_me] == '1' ? remember(user) : forget(user)
          flash.now[:success] = "Great job dude!"
          redirect_back_or user
        elsif !user.activated?
          message  = "Account not activated. "
          message += "Check your email for the activation link."
          flash[:warning] = message
          redirect_to root_url
        else
         flash.now[:danger] = "Something went wrong, please try again."
         render 'new'  
        end
      elsif !user.authenticate(params[:session][:password])
        flash.now[:danger] = "Incorrect password."
        render 'new'  
      else 
        flash.now[:danger] = "Something went wrong. Please try again."
        render 'new'
      end
    elsif !user 
      flash.now[:danger] = 'Incorrect email'
      render 'new'
    else  
      flash.now[:danger] = "Something went wrong, please try again or contact support."
      render 'new'
    end
  end

这可以通过尝试/错误测试来实现，但看起来并不理想/干燥。