ruby on Rails form_tag空提交值

Question

我按PARAMS [：commit] =='用户'按下按钮。但是在控制器操作值中始终=“”（空）。我做错了什么？

控制器类

class AdminController < ApplicationController 

    def show
    end

    def panel
        puts "Params ============================================= " 
        if params[:commit] == 'Users'
            puts "Users ============================================= " 
            puts params[:commit]
        elsif params[:commit] == 'Projects'
            puts "Projects ============================================= " 
            puts params[:commit]
        else              
            puts "ELSE  ============================================"
            puts params[:commit] 
        end
    end

end

视图面板.html.ERB

<%= form_tag url_for(action: 'panel'), method: "post" do %>
  <%= submit_tag 'User' %>
<% end %>

路由

Rails.application.routes.draw do
  root 'admin#show' 

  get  '/panel', to: "admin#panel"
end

日志

Processing by AdminController#panel as HTML
Params ============================================= 
ELSE  ============================================

  Rendering layout layouts/application.html.erb
  Rendering admin/panel.html.erb within layouts/application
  Rendered admin/panel.html.erb within layouts/application (Duration: 0.9ms | Allocations: 523)
  Rendered layout layouts/application.html.erb (Duration: 6.5ms | Allocations: 2745)
Completed 200 OK in 17ms (Views: 12.0ms | Allocations: 3047)