Mam zagnieżdżoną formę z kolumną file_field, gdy próbuję ją utworzyć zgłasza NoMethodError w UserController # update undefined method `[] 'for #

{
 "utf8"=>"✓",
 "authenticity_token"=>"HFWawKp4RH7+AFV0yQ1cXpzxHDfubKTKkiDiS6QKnJk=",
 "user"=> { 
  "name"=>"Test",
  "image_attributes"=> { 
    "picture"=>#<ActionDispatch::Http::UploadedFile:0x3f4e318
    @original_filename="Beautiful Sky_thumb.jpg",
    @content_type="image/jpeg",
    @headers="Content-Disposition: form-data; name=\"user[pics_attributes][pic]\"; filename=\"Beautiful Sky_thumb.jpg\"\r\nContent-Type: image/jpeg\r\n",
    @tempfile=#<File:C:/Users/Alex/AppData/Local/Temp/RackMultipart20120824-4784-5rmxid>>
  }
 },
"commit"=>"Save User"
}

Mój model

class User < ActiveRecord::Base
  attr_accessbile: :name, image_attributes
  has_many :images
  accepts_nested_attributes_for: images
end

class Image < ActiveRecord::Base
  belongs_to :verve_app
  mount_uploader picture, PictureUploader
end

Mój kontroler

def new
  @user = User.new
  @user.images.build
end

def create
  @user = User.new(params[:user])
  @user.save!
end

Mój widok

<%= form_for @user do |f| %>
  <%= f.hidden_field :name, {value: 'Alex'} %>
  <%= f.fields_for :image_attributes do |image| %>
    <%= image.file_field :picture %>
  <% end %>
  <%= user.submit %>
<% end %>