carrierwaveで画像を複数アップロードし､DBに保存

前提・実現したいこと

carrierwaveで画像を複数アップロードし､DBに保存
商品を保存するitemsテーブルと､画像を保存するphotosテーブルがあります
railsで複数の画像を持った商品出品機能を実装しようとしているのですが､画像を複数枚選択し､保存しようとしても保存されません｡
一枚でも保存できませんでした｡
エラーは発生していません｡

該当のソースコード

sample.html.haml

.product_listing_content
  = render "user-shared/user-header" 
  .product_listing_box
    .product_listing_title
      商品の情報を入力
    = form_with(model: @item, local: true, multipart: true) do |f|
      .upload_box
        .upload_text
          .upload_header 
            出品画像
          .upload_require 
            必須
        %p
          最大10枚までアップロードできます
        = fields_for :photos do |i|
          = i.label :img, class: "image_label", for: "image"  do
            .upload_image
              = i.file_field :img, name: "photos[img][]", multipart: true, class: "file_field", id: "image"
              %pre.image_text

sample.controller.rb

class ItemsController < ApplicationController

  def index
    
  end


  def new
    @category = Category.all.order("id ASC").limit(13)
    @postage = Postage.all.order("id ASC").limit(2)
    @prefecture = Prefecture.all
    @postage_day = PostageDay.all
    @state = State.all
    @item = Item.new
    @item.photos.build
 
    
end
  

  def category_children  
    @category_children = Category.find(params[:productcategory]).children
    end


  def category_grandchildren
    @category_grandchildren = Category.find(params[:productcategory]).children
    end

  def postage_children 
    @postage_children = Postage.find(params[:postageitem]).children
    
  end


  def create
    @item = Item.new(item_params)
    @item.save

    redirect_to root_path
  end




  def show
    @search_params = user_search_params
    @prefecrure = Prefecture.all
  end
  

private



  def user_search_params
    params.fetch(:search, {}).permit(:id,:prefecture)
  end

  def item_params
    params.require(:item).permit(:state_id, :name, :explain, :category_id, :price, :postage_id, :prefecture_id, :postage_day_id, photos_attributes: [:id, {img: []}, :item_id]).merge(user_id: 1, buyer_id: 1, shipping_date: 1, size_id: 1, brand_id: 1)
  end
end

item.rb

has_many :photos
accepts_nested_attributes_for :photos

photo.rb

class Photo < ApplicationRecord
  belongs_to :item, optional: true
  mount_uploaders :img, PhotoUploader
end

ターミナル
Started POST "/items" for ::1 at 2019-08-18 18:01:57 +0900
Processing by ItemsController#create as HTML
Parameters: {"utf8"=>"✓", "authenticity_token"=>"2r9aGxEbvqaTm+BMmz+lK0JBnYoHAwPRQrGqWsDwyH4sdND3LI8sz3zlA7z6rEX+N0Wx6YT2449ZfO+bd48peQ==", "photos"=>{"img"=>[#<ActionDispatch::Http::UploadedFile:0x00007fd08ac458a8 @tempfile=#Tempfile:/var/folders/tf/jtyh4t1n2k913fhwch5fqvxh0000gn/T/RackMultipart20190818-43340-mv15n2.jpg, @original_filename="book1.jpg", @content_type="image/jpeg", @headers="Content-Disposition: form-data; name="photos[img][]"; filename="book1.jpg"\r\nContent-Type: image/jpeg\r\n">]}, "item"=>{"name"=>"p", "explain"=>"p", "category_id"=>"100", "state_id"=>"1", "postage_id"=>"8", "prefecture_id"=>"1", "postage_day_id"=>"1", "price"=>"1000"}, "commit"=>"出品する"}

From: /Users/nakagawashuuma/Desktop/mercari/freemarket_sample_56b/app/controllers/items_controller.rb @ line 38 ItemsController#create:

36: def create
37:   @item = Item.new(item_params)

=> 38: binding.pry
39: @item.save
40: # @photo = Photo.new(photo_params)
41: # binding.pry
42: # @photo.save
43: redirect_to root_path
44: end

[1] pry(#<ItemsController>)> @item = Item.new(item_params)
=> #<Item:0x00007fd0923795c8
id: nil,
name: "p",
explain: "p",
state_id: 1,
price: 1000,
buyer_id: 1,
prefecture_id: 1,
shipping_date: 1,
size_id: 1,
brand_id: 1,
user_id: 1,
created_at: nil,
updated_at: nil,
category_id: 100,
postage_id: 8,
postage_day_id: 1>
[2] pry(#<ItemsController>)> params
=> <ActionController::Parameters {"utf8"=>"✓", "authenticity_token"=>"2r9aGxEbvqaTm+BMmz+lK0JBnYoHAwPRQrGqWsDwyH4sdND3LI8sz3zlA7z6rEX+N0Wx6YT2449ZfO+bd48peQ==", "photos"=>{"img"=>[#<ActionDispatch::Http::UploadedFile:0x00007fd08ac458a8 @tempfile=#Tempfile:/var/folders/tf/jtyh4t1n2k913fhwch5fqvxh0000gn/T/RackMultipart20190818-43340-mv15n2.jpg, @original_filename="book1.jpg", @content_type="image/jpeg", @headers="Content-Disposition: form-data; name="photos[img][]"; filename="book1.jpg"\r\nContent-Type: image/jpeg\r\n">]}, "item"=><ActionController::Parameters {"name"=>"p", "explain"=>"p", "category_id"=>"100", "state_id"=>"1", "postage_id"=>"8", "prefecture_id"=>"1", "postage_day_id"=>"1", "price"=>"1000"} permitted: false>, "commit"=>"出品する", "controller"=>"items", "action"=>"create"} permitted: false>
[3] pry(#<ItemsController>)> params[:photos][:img]
=> [#<ActionDispatch::Http::UploadedFile:0x00007fd08ac458a8
@content_type="image/jpeg",
@headers="Content-Disposition: form-data; name="photos[img][]"; filename="book1.jpg"\r\nContent-Type: image/jpeg\r\n",
@original_filename="book1.jpg",
@tempfile=#File:/var/folders/tf/jtyh4t1n2k913fhwch5fqvxh0000gn/T/RackMultipart20190818-43340-mv15n2.jpg>]
[4] pry(#<ItemsController>)>