Ruby on rails 我无法下载使用carrierwave上传的文件

以前我可以下载我上传的单个文件，但当我把它改为多个文件上传时，我无法下载请帮助我

这是我的控制器

发票\u详细信息\u controller.rb

    class InvoiceDetailsController < ApplicationController
      before_action :set_invoice_detail, only: [:show, :edit, :update, :destroy]

      respond_to :html

      def index
        @invoice_details = InvoiceDetail.all
        respond_with(@invoice_details)
      end

      def show
     @invoice_detail = InvoiceDetail.find(params[:id])

      respond_to do |format|
        format.html # show.html.erb
        format.xml  { render :xml => @invoice_detail }
        format.pdf { render :layout => false }
      end
      end

      def new
        @invoice_detail = InvoiceDetail.new
        respond_with(@invoice_detail)
      end

      def edit
      end

      def create
        @invoice_detail = InvoiceDetail.new(invoice_detail_params)
        respond_to do |format|
          if @invoice_detail.save
            format.html { redirect_to invoice_details_path, notice: 'Invoice was successfully created.' }
          else
            format.html { render action: "new" }
          end
        end
      end

      def update
        @invoice_detail.update(invoice_detail_params)
        redirect_to invoice_details_path
      end

      def destroy
        @invoice_detail.destroy
      redirect_to invoice_details_path
      end

      def download
          respond_to do |format|
            format.html {
                if params[:invoice_id].nil?
                    redirect_to :back
                else
                  begin
                    invoice = InvoiceDetail.find(params[:invoice_id])
                    attachment_file = File.join('public', invoice.attachment.url)
                    if File.exists?(attachment_file)
                      send_file attachment_file, :disposition => 'attachment'
                    else
                      redirect_to :back
                    end
                  rescue Exception => error
                    redirect_to :back
                  end
                end
            }
          end
      end

      private
        def set_invoice_detail
          @invoice_detail = InvoiceDetail.find(params[:id])
        end

        def invoice_detail_params
          params.require(:invoice_detail).permit(:attachment,:invoice_number, :supplier_name, :invoice_date, :invoice_due_date, :description_of_goods, :quatity, :price_per_unit, :total_amount, :mode_of_payment, :status, :shipping_country)
        end
    end
here are my models

invoice_details.rb

    class InvoiceDetail < ActiveRecord::Base
       has_many :attachment
       accepts_nested_attributes_for :attachment
    end

invoice_files.rb

    class InvoiceFile < ActiveRecord::Base
       mount_uploader :avatar, AvatarUploader
       belongs_to :InvoiceDetail
       validates :name, presence: true # Make sure the owner's name is present.
    end


here is my form

_form.html.erb

    <%= form_for(@invoice_detail , html: {class: 'form-horizontal', role: 'form' }) do |f| %>
      <% if @invoice_detail.errors.any? %>
        <div id="error_explanation">
          <h2><%= pluralize(@invoice_detail.errors.count, "error") %> prohibited this invoice_detail from being saved:</h2>

          <ul>
          <% @invoice_detail.errors.full_messages.each do |message| %>
            <li><%= message %></li>
          <% end %>
          </ul>
        </div>
      <% end %>

        <div class="field">
            <%= f.label :invoice_number, :class => 'control-label' %>
                <div class="controls">
        <%= f.text_field :invoice_number, :class => 'text_field', :required => true, :maxlength => 15, :placeholder =>'15 Alpha Numeric with special Characters', :presence => "check invoice num"   %>
      </div>
      </div>
        <div class="field">
        <%= f.label :supplier_name, :class => 'control-label' %>
                    <div class="controls">

        <%= f.text_field :supplier_name, :class => 'text_field', :required => true,:maxlength => 20, :placeholder => '20 Alpha numeric characters'  %>
        </div>
      </div>
      <div class="field">
        <%= f.label :invoice_date, :class => 'control-label' %>
                    <div class="controls1">

        <%= f.date_select :invoice_date, :class => 'text_area' %>
        </div>
      </div>
      <div class="field">
        <%= f.label :invoice_due_date, :class => 'control-label' %>
                    <div class="controls1">

        <%= f.date_select :invoice_due_date, :class => 'text_area' %>
        </div>

      </div>
      <div class="field">
        <%= f.label :description_of_goods, :class => 'control-label' %>
                        <div class="controls">

        <%= f.text_area :description_of_goods, :class => 'text_area', :maxlength => 50, :placeholder => 'Accepts up to 50 Alpha Numeric with special Characters'%>
        </div>
      </div>
      <div class="field">
        <%= f.label :quality, :class => 'control-label' %>
                        <div class="controls">

        <%= f.text_field :quatity , :class => 'text_area',:maxlength => 10, :placeholder =>'Accepts up to 10 Digits'%>
        </div>
      </div>
      <div class="field">
        <%= f.label :price_per_unit, :class => 'control-label' %>
                        <div class="controls">

        <%= f.text_field :price_per_unit, :class => 'text_area',:maxlength => 15,  :placeholder =>'Accepts up to 15 Digits' %>
        </div>
      </div>
      <div class="field">
        <%= f.label :total_amount, :class => 'control-label' %>
                        <div class="controls">

        <%= f.text_field :total_amount, :class => 'text_area', :maxlength => 15, :placeholder =>'Accepts up to 15 Digits'  %>
        </div>
      </div>
      <div class="field">
        <%= f.label :mode_of_payment, :class => 'control-label' %>
                        <div class="controls">

        <%= f.select :mode_of_payment, options_for_select(%w[Cash Cheque Transfer LC]), :class => 'text_area', :placeholder => 'Select mode of payment' %>
        </div>
      </div>
      <div class="field">
        <%= f.label :status, :class => 'control-label' %>
                            <div class="controls">

        <%= f.select :status, options_for_select(%w[Paid Pending]), :class => 'text_area' %>
        </div>
      </div>
      <div class="field">
        <%= f.label :shipping_country, :class => 'control-label' %>
                            <div class="controls">

        <%= f.country_select :shipping_country, {priority: %w(ID US CA), prompt: 'Please select a country'}, :class => 'text_area' %>
        </div>
      </div>
         <div class="control-group">
          <%= f.label :attachment , :class => 'control-label' %>
          <div class="controls">
            <%= f.file_field :avatar, :multiple => true, name: "attachment[avatar][]", :class => 'file_field', :required => true %>
          </div>
        </div>
      <div class="form-actions1">
        <%= f.submit  :class => 'btn btn-primary' %>
        <%#= f.submit "cancel", :class => 'btn btn-danger', method: :delete, data: { confirm: 'Are you sure you want to cancel' } %>

<%= form_for(@invoice_detail , html: {class: 'form-horizontal', role: 'form' }) do |f| %>
  <% if @invoice_detail.errors.any? %>
    <div id="error_explanation">
      <h2><%= pluralize(@invoice_detail.errors.count, "error") %> prohibited this invoice_detail from being saved:</h2>

      <ul>
      <% @invoice_detail.errors.full_messages.each do |message| %>
        <li><%= message %></li>
      <% end %>
      </ul>
    </div>
  <% end %>

    <div class="field">
        <%= f.label :invoice_number, :class => 'control-label' %>
            <div class="controls">
    <%= f.text_field :invoice_number, :class => 'text_field', :required => true, :maxlength => 15, :placeholder =>'15 Alpha Numeric with special Characters', :presence => "check invoice num"   %>
  </div>
  </div>
    <div class="field">
    <%= f.label :supplier_name, :class => 'control-label' %>
                <div class="controls">

    <%= f.text_field :supplier_name, :class => 'text_field', :required => true,:maxlength => 20, :placeholder => '20 Alpha numeric characters'  %>
    </div>
  </div>
  <div class="field">
    <%= f.label :invoice_date, :class => 'control-label' %>
                <div class="controls1">

    <%= f.date_select :invoice_date, :class => 'text_area' %>
    </div>
  </div>
  <div class="field">
    <%= f.label :invoice_due_date, :class => 'control-label' %>
                <div class="controls1">

    <%= f.date_select :invoice_due_date, :class => 'text_area' %>
    </div>

  </div>
  <div class="field">
    <%= f.label :description_of_goods, :class => 'control-label' %>
                    <div class="controls">

    <%= f.text_area :description_of_goods, :class => 'text_area', :maxlength => 50, :placeholder => 'Accepts up to 50 Alpha Numeric with special Characters'%>
    </div>
  </div>
  <div class="field">
    <%= f.label :quality, :class => 'control-label' %>
                    <div class="controls">

    <%= f.text_field :quatity , :class => 'text_area',:maxlength => 10, :placeholder =>'Accepts up to 10 Digits'%>
    </div>
  </div>
  <div class="field">
    <%= f.label :price_per_unit, :class => 'control-label' %>
                    <div class="controls">

    <%= f.text_field :price_per_unit, :class => 'text_area',:maxlength => 15,  :placeholder =>'Accepts up to 15 Digits' %>
    </div>
  </div>
  <div class="field">
    <%= f.label :total_amount, :class => 'control-label' %>
                    <div class="controls">

    <%= f.text_field :total_amount, :class => 'text_area', :maxlength => 15, :placeholder =>'Accepts up to 15 Digits'  %>
    </div>
  </div>
  <div class="field">
    <%= f.label :mode_of_payment, :class => 'control-label' %>
                    <div class="controls">

    <%= f.select :mode_of_payment, options_for_select(%w[Cash Cheque Transfer LC]), :class => 'text_area', :placeholder => 'Select mode of payment' %>
    </div>
  </div>
  <div class="field">
    <%= f.label :status, :class => 'control-label' %>
                        <div class="controls">

    <%= f.select :status, options_for_select(%w[Paid Pending]), :class => 'text_area' %>
    </div>
  </div>
  <div class="field">
    <%= f.label :shipping_country, :class => 'control-label' %>
                        <div class="controls">

    <%= f.country_select :shipping_country, {priority: %w(ID US CA), prompt: 'Please select a country'}, :class => 'text_area' %>
    </div>
  </div>
     <div class="control-group">
      <%= f.label :attachment , :class => 'control-label' %>
      <div class="controls">
        <%= f.file_field :avatar, :multiple => true, name: "attachment[avatar][]", :class => 'file_field', :required => true %>
      </div>
    </div>
  <div class="form-actions1">
    <%= f.submit  :class => 'btn btn-primary' %>
    <%#= f.submit "cancel", :class => 'btn btn-danger', method: :delete, data: { confirm: 'Are you sure you want to cancel' } %>
    <%= link_to "Cancel", invoice_details_path(), :class => 'btn btn-danger', data: { confirm: 'Are you sure you want to cancel' } %>

  </div>
<% end %>
      <%= link_to "Cancel", invoice_details_path(), :class => 'btn btn-danger', data: { confirm: 'Are you sure you want to cancel' } %>

      </div>
    <% end %>

类InvoiceDetailsController@invoice_detail}
format.pdf{render:layout=>false}
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def新
@发票详细信息=发票详细信息.new
回复（@invoice\u detail）
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定义编辑
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def创建
@发票详细信息=发票详细信息。新建（发票详细信息参数）
回应待办事项|格式|
如果@invoice\u detail.save
format.html{将\重定向到发票\详细信息\路径，注意：'发票已成功创建。}
其他的
format.html{呈现操作：“新建”}
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def更新
@发票详细信息。更新（发票详细信息参数）
将\u重定向到发票\u详细信息\u路径
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def销毁
@销毁发票
将\u重定向到发票\u详细信息\u路径
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def下载
回应待办事项|格式|
format.html{
如果参数为[：发票号].nil？
重定向到：返回
其他的
开始
发票=InvoiceDetail.find（参数[：发票id]）
附件文件=file.join（'public'，invoice.attachment.url）
如果文件存在？（附件文件）
发送\u文件附件\u文件，：disposition=>“附件”
其他的
重定向到：返回
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rescue异常=>错误
重定向到：返回
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}
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私有的
def设置\u发票\u详细信息
@发票详细信息=发票详细信息.find（参数[：id]）
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def发票详细信息参数
参数要求（：发票详细信息）。许可（：附件，：发票编号，：供应商名称，：发票日期，：发票到期日期，：货物描述，：数量，：单价，：总金额，：付款方式，：状态，：装运国家）
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这是我的模型
发票详细信息.rb
类InvoiceDetail


'控件标签'%>
'text_field'，：required=>true，：maxlength=>15，：placeholder=>'15带特殊字符的字母数字'，：presence=>“check invoice num”%>
'控件标签'%>
“text_field'，：required=>true，：maxlength=>20，：placeholder=>20个字母数字字符'%>
'控件标签'%>
'文本区域'%>
'控件标签'%>
'文本区域'%>
'控件标签'%>
“text_area'，：maxlength=>50，：placeholder=>”最多可接受50个带有特殊字符“%”的字母数字
'控件标签'%>
“text_area'，：maxlength=>10，：placeholder=>”最多可接受10位“%”
'控件标签'%>
“text_area'，：maxlength=>15，：placeholder=>”最多可接受15位“%”
'控件标签'%>
“text_area'，：maxlength=>15，：placeholder=>”最多可接受15位“%”
'控件标签'%>
'文本\区域'，：占位符=>'选择付款方式'%>
'控件标签'%>
'文本区域'%>
'控件标签'%>
'文本区域'%>
'控件标签'%>
true，name:“附件[avatar][]”，：class=>file\u field，：required=>true%>
“btn btn主节点”%>
'btn btn danger'，方法：：删除，数据：{确认：'是否确实要取消'}%>
禁止保存此发票详细信息：



'控件标签'%>
'text_field'，：required=>true，：maxlength=>15，：placeholder=>'15带特殊字符的字母数字'，：presence=>“check invoice num”%>
'控件标签'%>
“text_field'，：required=>true，：maxlength=>20，：placeholder=>20个字母数字字符'%>
'控件标签'%>
'文本区域'%>
'控件标签'%>
'文本区域'%>
'控件标签'%>
“text_area'，：maxlength=>50，：placeholder=>“最多可接受50个带有特殊字符的字母数字”
def download_video
  @video = Video.find params[:id]
  redirect_to @video..avatar.expiring_url(10)

end