ruby-on-rails – 为什么活动存储会抛出这个错误：nil的未定义方

这就是我所做的.

>我已经运行了迁移：rails active_storage：install
>我编辑了我的开发环境文件：config.active_storage.service =：local
>与我的生产文件相同：config.active_storage.service =：amazon
>我确保使用has_one_attached：image正确设置了我的模型

我的控制器：

class EventsController < ApplicationController 
  def create
    @event = Event.new(event_params)
    @event.save
  end

  private

  def event_params 
    params.require(:event).permit(:name,:image)
  end
end

这是表格：

<%= simple_form_for(@event,url: events_path,method: :post) do |f| %>
  <%= f.input :name %>

  <%= f.input :image %>

  <%= f.submit %>
<% end %>

这是模型：

class Event < ActiveRecord::Base

  has_one_attached :image

  acts_as_list

end

值得一提的是,我正在将此特定项目升级到rails 5.它还习惯使用回形针.

问题：
当我提交此表单时,会抛出上述错误.相同
尝试更新@event对象时发生错误.

更新

>在查看框架跟踪时,错误将在此行上抛出：blob.upload io.奇怪的是,当我调试这条线时,blob不是零.它拥有一个没有id的ActiveStorage :: Blob.而且io也不是零.

错误日志：

我故意取出真品令牌.

Started POST "/events" for ::1 at 2018-08-23 10:02:25 -0600
Processing by EventsController#create as HTML
  Parameters: {"utf8"=>"?","authenticity_token"=>"*****************","event"=>{"name"=>"test event","image"=>#<ActionDispatch::Http::UploadedFile:0x00007fc816e90af8 @tempfile=#<Tempfile:/var/folders/f9/q3x5477d1dxd7fxjbrl2tvch0000gn/T/RackMultipart20180823-61111-14dih2d.jpg>,@original_filename="sample-image.jpg",@content_type="image/jpeg",@headers="Content-Disposition: form-data; name="event[image]"; filename="sample-image.jpg"rnContent-Type: image/jpegrn">},"commit"=>"Update Event"}
Completed 500 Internal Server Error in 61ms (ActiveRecord: 0.0ms)



NoMethodError (undefined method `upload' for nil:NilClass):

app/controllers/events_controller.rb:4:in `create'
::1 - - [23/Aug/2018:10:02:25 MDT] "POST /events HTTP/1.1" 500 138644
http://localhost:3000/ -> /events