rails 4 paperclip：缺少必需的attr_accessor

Question

I have a problem with paperclip and rails 4. When uploading an image, I get the following error:

Image model missing required attr_accessor for 'pic_file_name'

When adding the recommended attr_accessors

  attr_accessor :pic_file_name
  attr_accessor :pic_content_type
  attr_accessor :pic_file_size
  attr_accessor :pic_updated_at

the record is saved but the :pic column is empty, nothing was uploaded.

I also tried whitelisting :pic_file_name

 private
    # Use callbacks to share common setup or constraints between actions.
    def set_image
      @image = Image.find(params[:id])
    end

    # Never trust parameters from the scary internet, only allow the white list through.
    def image_params
      params.require(:image).permit(:title, :pic, :pic_file_name)
    end

but no success.

Any ideas what is wrong here?

Answer 1

I have solved this by creating a new column

 def change
    add_column :images, :pic_file_name, :string
  end

might be necessary for rails 4 apps, don't know. Works now.

Answer 2

Try implementing pic_file_name

def pic_file_name
 pic
end

def pic_file_name(file_name)
 pic = file_name
end