paperclip No handler found for “file.jpg” rails 4

问题

I'm having problem with setting up paperclip gem in one of me apps.
I get No handler found for error message when i try to save uploaded file.

Things that I've done

• migration:

  add_attachment :orders, :file  
  

• model:

  has_attached_file :file  
  validates_attachment_content_type :file, :content_type => /\Aimage\/.*\Z/
  

• controller:

  def order_params  
    params.require(:order).permit(:file)
  

• view:

  form_tag url, method: :post, html: {multipart: true}  
  ...  
  = file_field_tag 'order[file]', disabled: true, id: 'mtd_file',accept: 'image/png,image/gif,image/jpeg'
  

When I try to execute in my controller Order.create params[order] I get error

No handler found for "file.jpg"

When I look into order[file] param I see that it's a string file.jpg (name of uploaded file).

回答1:

Try using the below line of code, you don't have to pass mulitpart as html hash

form_tag url, method: :post, multipart: true

For form_for you have to pass multipart in html hash

form_for(@user), :html => { :multipart => true } do |f|

For more info, you can refer to the documentation: RailsGuides - Form Helpers - 5 Uploading Files

来源：https://stackoverflow.com/questions/29094795/paperclip-no-handler-found-for-file-jpg-rails-4