注册是另一个表单的一部分时设计错误消息

Question

我目前在另一个表单中有一个设计注册表。提交父表单后，我创建了一个用户并将其登录。但我无法收到错误通知。

这是表格

= form_tag orders_path, id: 'payment-form' do
        #formShipping.modal.fade{"aria-hidden" => "true", "aria-labelledby" => "productShippingLabel", :role => "dialog", :tabindex => "-1"}
      .modal-dialog
        .modal-content
          .modal-header
            %button.close{"data-dismiss" => "modal", :type => "button"}
              %span{"aria-hidden" => "true"} ×
              %span.sr-only Close
            %h4#myModalLabel.modal-title Payment Form
          .modal-body
            / Button trigger modal
            .panel.panel-default
              .panel-heading Donor Information
              .panel-body
                .col-md-3
                .col-md-6
                  - if current_user
                    .text-center
                      You're already a member
                  - else
                    .default-info
                      %label{:for => "name"} Name
                      %input.form-control{:type => "text", :name => "name"}/
                      %label{:for => "email"} Email
                      %input.form-control{:type => "text", :name => "email"}/
                    .hide-info
                      = form_for(resource, :as => resource_name, :url => session_path(resource_name), :id => "form2") do |f|
                        = devise_error_messages!
                        %p
                          %label{:for => "name"} Name
                          %input.form-control{:type => "text", :name => "name"}/
                          = f.label :email
                          %br/
                          = f.text_field :email, class: "form-control"
                          = f.label :password
                          - if @validatable
                            %i
                              (#{@minimum_password_length} characters minimum)
                          %br/
                          = f.password_field :password, autocomplete: "off", class: "form-control"
                          = f.label :password_confirmation
                          %br/
                          = f.password_field :password_confirmation, autocomplete: "off", class: "form-control"
                  .col-md-3
            .panel.panel-default
              .panel-heading
                %h3.panel-title Card information
              .panel-body
                %span.payment-errors
                .row
                  .col-md-6
                    %label{:for => "name"} Card Number
                    %input.form-control{:type => "text", "data-stripe" => "number"}/
                  .col-md-3
                    %label{:for => "name"} CVC
                    %input.form-control{:placeholder => "Ex. 331", :type => "text", "data-stripe" => "cvc"}/
                  .col-md-3
                    = label_tag :card_month, "Expiration"
                    = select_month nil, {add_month_numbers: true}, {name: nil, id: "card_month", "data-stripe" => "exp-month"}
                    = select_year nil, {start_year: Date.today.year, end_year: Date.today.year+15}, {name: nil, id: "card_year", "data-stripe" => "exp-year"}
                .text-center
                  %h2.total-amount
                    Total:
                    $0.00
                  %input{:name => "terms", :type => "CHECKBOX"}>/
                  Agree to terms?
                  %br/
                  %br
                %input{:name => "store_front", :type => "hidden", :value => @store_front.id}/
                .text-center
                  %button.btn.btn-primary{:type => "submit"} Pay Now!

这是用户保存的控制器操作

  @user = User.new(:email => params[:user][:email], :password => params[:user][:password],    #values from params
       :password_confirmation => params[:user][:password_confirmation])
        @user.update_attributes(:subscriber => true)
        @user.save
        sign_in @user

如何正确显示我的设计错误消息？