Rails link_to 和 button_to 的區別

• link_to   &   button_to

  link_to 和 button_to 其實還是存在很大區別的，我們可以查看一下源代碼。
  
  源代碼：
  https://github.com/rails/rails/blob/master/actionview/lib/action_view/helpers/url_helper.rb

  def link_to(name = nil, options = nil, html_options = nil, &block)
      html_options, options, name = options, name, block if block_given?
      options ||= {}  
  
      html_options = convert_options_to_data_attributes(options, html_options)
  
      url = url_for(options)  
  
      html_options["href".freeze] ||= url
      content_tag("a".freeze, name || url, html_options, &block)
    end
  
  //====================================================================
  
  def button_to(name = nil, options = nil, html_options = nil, &block)
      html_options, options = options, name if block_given?
      options      ||= {}
      html_options ||= {}
      html_options = html_options.stringify_keys  
  
      url    = options.is_a?(String) ? options : url_for(options)
      remote = html_options.delete("remote")
      params = html_options.delete("params")  
  
      method     = html_options.delete("method").to_s
      method_tag = BUTTON_TAG_METHOD_VERBS.include?(method) ? method_tag(method) : "".freeze.html_safe  
  
      form_method  = method == "get" ? "get" : "post"
      form_options = html_options.delete("form") || {}
      form_options[:class] ||= html_options.delete("form_class") || "button_to"
      form_options[:method] = form_method
      form_options[:action] = url
      form_options[:'data-remote'] = true if remote  
  
      request_token_tag = if form_method == "post"
        request_method = method.empty? ? "post" : method
        token_tag(nil, form_options: { action: url, method: request_method })
      else
        "".freeze
      end  
  
      html_options = convert_options_to_data_attributes(options, html_options)
      html_options["type"] = "submit"  
  
      button = if block_given?
        content_tag("button", html_options, &block)
      else
        html_options["value"] = name || url
        tag("input", html_options)
      end  
  
      inner_tags = method_tag.safe_concat(button).safe_concat(request_token_tag)
      if params
        to_form_params(params).each do |param|
          inner_tags.safe_concat tag(:input, type: "hidden", name: param[:name], value: param[:value])
        end
      end
      content_tag("form", inner_tags, form_options)
    end
  

  從源代碼中可以看出link_to是用url方式跳轉的，默認get方式。 而button_to則是生成一個form表單進行提交，默認是post方式。因此他們的使用方法也略有差異，具體使用可以參照github，本章節介紹日常中經常會使用到的一種使用。

  // Routes 
  resources :gbms_dous do
     collection do
       post 'saveSingleDou', to: 'saveSingleDou', as: 'save_single'
       post 'saveMultiDou', to: 'saveMultiDou', as: 'save_multi'
       post 'reloadSingleDou', to: 'reloadSingleDou', as: 'reload_single'
     end
    end
  
  // Page
  <%= link_to 'Reload',  reload_single_gbms_dous_path({id:"#{@dou.DOUID}"}), method: :post , :class=>'btn btn-info btn-sm glyphicon glyphicon-refresh' %>
  
  <%= button_to('Save',save_single_gbms_dous_path,method: :post, params: {:id=>@dou.DOUID}, :class=>'btn btn-info btn-sm')%>
  
  // Controller
   def saveSingleDou
      douID = params[:id]
    …..
    end