Rails报错No route matches [POST] "/login" 路由错误解决方案

No route matches [POST] "/login" 是因为路由仅配置了GET /login规则用于渲染登录页，但表单提交默认发送POST请求，请求方法与路由允许的匹配规则不匹配。
现有路由配置中get "/login", to:"contacts#loginuser", as: :loginuser仅能响应GET类型的/login请求，无法接收表单提交的POST请求。

1. 补全路由配置 #

修改config/routes.rb中的登录相关路由，拆分页面渲染和表单提交的路由规则，符合Rails RESTful设计规范：

root to: 'pages#home'

# 替换原有单条get登录路由
get "/login", to: "contacts#loginuser", as: :loginuser # 响应GET请求，返回登录表单页
post "/login", to: "contacts#login", as: :login_submit # 响应POST请求，处理登录校验逻辑

# 其他原有路由保持不变
resources :admins
resources :clients do
  resources :change_policies, only: %i[ index new create edit update destroy]
  resources :age_policies, only: %i[index new create edit update destroy]
  resources :refund_policies, only: %i[index new create edit update destroy]
  resources :reservation_policies, only: %i[index new create edit update destroy]
  resources :cancel_policies, only: %i[index new create edit update destroy]
  resources :rooms, only: %i[index new create edit update destroy]
  resources :contacts, only: %i[index new create edit update destroy]
  resources :reservations, only: %i[index new create edit update show destroy]    
end

resources :reservation, only: %i[index] do
  resources :item_reservations, only: %i[index new create edit update destroy]
  resources :user_reservations, only: %i[index new create edit update destroy]
  resources :other_reservations, only: %i[index new create edit update destroy]
  resources :obs_reservations, only: %i[index new create edit update destroy]
end

resources :registrations, only: %i[new create]

不推荐为了省事直接用match "/login", to: "contacts#loginuser", via: [:get, :post]把两种请求合并到同一个控制器方法，会让方法逻辑混杂，提升后期维护成本。

2. 修改表单提交地址 #

调整登录视图中表单的提交路径，指向新增的POST路由：

<div class="container">
  <div class="row">
    <div class="col-sm-12 col-md-6 text-center">
      <%= image_tag "Motorhotel.png", class: "Logo img-fluid", alt: 'Logo_App' %>
    </div>
    <div class="col-sm-12 col-md-6">
    <br>
      <h2 class="pb-4 text"><%= "Ingresar" %></h2>
      <%# 将原url: loginuser_path 替换为POST路由对应的路径方法 %>
      <%= simple_form_for :contacts, url: login_submit_path do |f| %>
        <%= f.input :mail, label: "Correo Electronico" %>
        <%= f.input :pass, label: "Contraseña" %>
        <%= f.submit "Admitir" %>
      <% end %>
    </div> 
  </div>
</div>

3. 补充控制器处理逻辑 #

在app/controllers/contacts_controller.rb中新增login方法，处理表单提交的账号校验、登录态写入逻辑，参考示例：

def login
  # 匹配管理员或客户账号
  user = Admin.find_by(mail: params[:contacts][:mail]) || Client.find_by(mail: params[:contacts][:mail])
  # 校验密码（需模型中has_secure_password配合authenticate方法）
  if user&.authenticate(params[:contacts][:pass])
    session[:current_user_id] = user.id
    session[:user_type] = user.class.name
    redirect_to root_path, notice: "登录成功"
  else
    redirect_to loginuser_path, alert: "邮箱或密码错误"
  end
end

原有loginuser方法仅保留渲染登录页的逻辑即可，无需额外处理请求参数。

4. 验证路由生效 #

在项目根目录执行命令rails routes | grep login，终端输出如下两行结果即代表配置正确：

loginuser     GET    /login(.:format)    contacts#loginuser
login_submit  POST   /login(.:format)    contacts#login

内容的提问来源于stack exchange，提问作者Juan Pablo Grover Pinto