问多次上传Rails回形针未保存

EN

class Guitar < ActiveRecord::Base
  belongs_to :user
  has_many :photos

  accepts_nested_attributes_for :photos
end

class Photo < ActiveRecord::Base
  belongs_to :guitars

  has_attached_file :photo, styles: {
        thumb: '100x100>',
        square: '200x200#',
        medium: '300x300>',
        large: '600x600#' }
end

class GuitarsController < ApplicationController
  before_action :set_guitar, only: [:show, :edit, :update, :destroy]

  # GET /guitars
  # GET /guitars.json
  def index
    @guitars = Guitar.all
  end

  # GET /guitars/1
  # GET /guitars/1.json
  def show
  end

  # GET /guitars/new
  def new
    @guitar = Guitar.new
    3.times { @guitar.photos.build }
  end

  # GET /guitars/1/edit
  def edit
    @guitar = Guitar.find(params[:id])
    3.times { @guitar.photos.build }
  end

  # POST /guitars
  # POST /guitars.json
  def create
    @guitar = Guitar.new(guitar_params)
    @guitar.user_id = current_user.id if current_user

    respond_to do |format|
      if @guitar.save
    format.html { redirect_to @guitar, notice: 'Guitar was successfully created.' }
    format.json { render action: 'show', status: :created, location: @guitar }
      else
    format.html { render action: 'new' }
    format.json { render json: @guitar.errors, status: :unprocessable_entity }
      end
    end
  end

  # PATCH/PUT /guitars/1
  # PATCH/PUT /guitars/1.json
  def update
    respond_to do |format|
      if @guitar.update(guitar_params)
    format.html { redirect_to @guitar, notice: 'Guitar was successfully updated.' }
    format.json { head :no_content }
      else
    format.html { render action: 'edit' }
    format.json { render json: @guitar.errors, status: :unprocessable_entity }
      end
    end
  end

  # DELETE /guitars/1
  # DELETE /guitars/1.json
  def destroy
    @guitar.destroy
    respond_to do |format|
      format.html { redirect_to guitars_url }
      format.json { head :no_content }
    end
  end

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

    # Never trust parameters from the scary internet, only allow the white list through.
    def guitar_params
      params.require(:guitar).permit(:make, :model, :year, :color, :serial, :price, :condition, :kind, :bodykind, :frets, :one_owner, :user_id)
    end
end

<p>
  <strong>Make:</strong>
  <%= @guitar.make %>
</p>

<p>
  <strong>Model:</strong>
  <%= @guitar.model %>
</p>

<p>
  <strong>Year:</strong>
  <%= @guitar.year %>
</p>

<p>
  <strong>Color:</strong>
  <%= @guitar.color %>
</p>

<p>
  <strong>Serial:</strong>
  <%= @guitar.serial %>
</p>

<p>
  <strong>Price:</strong>
  <%= @guitar.price %>
</p>

<p>
  <strong>Condition:</strong>
  <%= @guitar.condition %>
</p>

<p>
  <strong>Kind:</strong>
  <%= @guitar.kind %>
</p>

<p>
  <strong>Bodykind:</strong>
  <%= @guitar.bodykind %>
</p>

<p>
  <strong>Frets:</strong>
  <%= @guitar.frets %>
</p>

<p>
  <strong>One owner:</strong>
  <%= @guitar.one_owner %>
</p>

<p>
  <strong>User:</strong>
  <%= @guitar.user_id %>
</p>

<div class="thumb">
    <% for asset in @guitar.photos %>
      <%= link_to image_tag(photo.photos.url(:thumb)), photo.photo.url(:original) %>
    <% end %>
</div>

<%= link_to 'Edit', edit_guitar_path(@guitar) %> |
<%= link_to 'Back', guitars_path %>

<%= simple_form_for(@guitar, html: { class: 'form-horizontal', :multipart => true}) do |f| %>
  <% if @guitar.errors.any? %>
    <div id="error_explanation">
      <h2><%= pluralize(@guitar.errors.count, "error") %> prohibited this guitar from being saved:</h2>

      <ul>
      <% @guitar.errors.full_messages.each do |msg| %>
    <li><%= msg %></li>
      <% end %>
      </ul>
    </div>
  <% end %>

  <%= f.input :make, label: 'Make of the Guitar', placeholder: 'Gibson' %>
  <%= f.input :model, label: 'Model of the Guitar', placeholder: 'Les Paul' %>
  <%= f.input :year, label: 'Year Made', placeholder: '1957' %>
  <%= f.input :color, label: 'Color', placeholder: 'GoldTop' %>
  <%= f.input :serial, label: 'Serial', placeholder: '#7-8789' %>
  <%= f.input :price, label: 'Price' %>
  <%= f.input :condition, label: 'Condition, 1-10' %>
  <%= f.input :kind, label: 'Kind of Guitar', placeholder: '6-String-Electric' %>
  <%= f.input :bodykind, label: 'Body Type', placeholder: 'Solid String Electric' %>
  <%= f.input :frets, label: 'Number of Frets', placeholder: '22' %>
  <%= f.input :one_owner, label: 'Original Owner' %>

  <%= f.fields_for :photos do |photo| %>
    <% if photo.object.new_record? %>
      <%= photo.file_field :photo %>
    <% end %>
  <% end %>

  <div class="actions">
    <%= f.submit %>
  </div>
<% end %>