undefined method `stringify_keys'

问题

When I try to upload image using Paperclip gem I got this error:

NoMethodError (undefined method `stringify_keys' for <ActionDispatch::Http::UploadedFile:0x000000025387f0>)

class MenuItem < ActiveRecord::Base
 has_one :image


end

class Image < ActiveRecord::Base
 belongs_to :menu_item
 has_attached_file :image, :styles => {
            :large => "640x480",
            :medium => "300x300", 
            :thumb => "100x100" 
           }
end

回答1:

I've seen this error happen before, usually when people attempt to call update_attributes like this:

update_attributes(params[:image])

The call should actually be this:

update_attributes(:image => params[:image])

A bit of a shot in the dark, but if that's it I'm sure we'll all be impressed.

回答2:

After struggling for a while in rails 3.2.2 I managed to solve this in this manner

(image = Image.new(image: params[:image])).save

update_attributes(image: image)

回答3:

I just had this problem, and to clarify things a bit, update_attributes is different from update_attribute.

The following should work:

update_attributes(:image => params[:image])

or

update_attribute(:image, params[:image])

There you go! There are other issues with update_attributes related to attr_accesible, but either works.

来源：https://stackoverflow.com/questions/8514970/undefined-method-stringify-keys