Rails 4: Duplicated file_field input on Nested Form - ruby-on-rails

Question

I have a model "post" and a model "photo". The model post have a nested form from photo to upload images with association. The upload works fine, but everytime I go to edit the post, I have a new input to each image uploaded and one more input to upload a new image. I want to have just the input to upload a new file and hide or not load the others.
Here is my code:
<%= f.fields_for :photos do |photo| %>
<%= photo.file_field :image, class: "form-control" %>
<% end %>
Controller:
module Admin
class SeminovosController < SuperAdminController
before_action :set_seminovo, only: [:show, :edit, :update, :destroy]
# GET /seminovos
# GET /seminovos.json
def index
#seminovos = Seminovo.all
#seminovo = Seminovo.new
#seminovo.photos.build
#expires_in 3.hours, :public => true, 'max-stale' => 0
end
# GET /seminovos/1
# GET /seminovos/1.json
def show
end
# GET /seminovos/new
def new
#seminovo = Seminovo.new
#seminovo.photos.build
#seminovo.photos
end
# GET /seminovos/1/edit
def edit
#seminovo.photos.build
#seminovo.photos
end
# POST /seminovos
# POST /seminovos.json
def create
##seminovo = Seminovo.new(seminovo_params)
respond_to do |format|
#seminovo = Seminovo.new(seminovo_params)
#seminovo.save
format.html { redirect_to #seminovo }
format.js
# if #seminovo.save
# format.html { redirect_to #seminovo, notice: 'Seminovo was successfully created.' }
# format.json { render :show, status: :created, location: #seminovo }
# else
# format.html { render :new }
# format.json { render json: #seminovo.errors, status: :unprocessable_entity }
# end
end
end
# PATCH/PUT /seminovos/1
# PATCH/PUT /seminovos/1.json
def update
respond_to do |format|
if #seminovo.update(seminovo_params)
format.html { redirect_to #seminovo, notice: 'Seminovo was successfully updated.' }
format.json { render :show, status: :ok, location: #seminovo }
else
format.html { render :edit }
format.json { render json: #seminovo.errors, status: :unprocessable_entity }
end
end
end
# DELETE /seminovos/1
# DELETE /seminovos/1.json
def destroy
#seminovo.destroy
respond_to do |format|
format.html { redirect_to seminovos_url, notice: 'Seminovo was successfully destroyed.' }
format.json { head :no_content }
end
end
private
# Use callbacks to share common setup or constraints between actions.
def set_seminovo
#seminovo = Seminovo.friendly.find(params[:id])
end
# Never trust parameters from the scary internet, only allow the white list through.
def seminovo_params
params.require(:seminovo).permit(:name, :price, :marca_id, :tipo_id, :ano_modelo,
:portas, :km_rodados, :combustivel, :placa, :cor, :desc,
:video, :destaque, :photo_id, :slug,
photos_attributes: [ :id, :image, :image_uid, :image_name, :desc,
:seminovos_id, :_destroy ])
end
end
end

Answer 1

Remove
#seminovo.photos.build
#seminovo.photos
from new and edit action.
Then replace
<%= f.fields_for :photos do |photo| %>
<%= photo.file_field :image, class: "form-control" %>
<% end %>
With
<%= f.fields_for :photos, #seminovo.photos.new do |photo| %>
<%= photo.file_field :image, class: "form-control" %>
<% end %>