Accessing values of ActionController Parameters - ruby-on-rails

Question

I need to access to the attachments values, I can't find the way
it says permitted false, it's allowed in the strong parameters though...
<ActionController::Parameters {
"utf8"=>"✓",
"authenticity_token"=>"wMY3FheLXzezCBO8phfst85DGdSBmVRl+nljAUYviYxZsWXMXC+Rcddit3XaNNikaGTvdLH+rx5ZNh6bY31Yzw==",
"finished_guitar"=><ActionController::Parameters
{ "title"=>"my super title",
"description"=>"and my awsome description"
} permitted: false>,
"commit"=>"Create Finished guitar",
"params"=>{
"attachments"=>[{"image"=>#<ActionDispatch::Http::UploadedFile:0x007fcfa084fa90 #tempfile=#<Tempfile:/var/folders/11/mdddnw8d0zd961bsfkq1cjy00000gn/T/RackMultipart20180902-64552-9bms50.jpg>,
#original_filename="image_1.jpg",
#content_type="image/jpeg",
#headers="Content-Disposition: form-data; name=\"params[attachments][][image]\";
filename=\"image_1.jpg\"\r\nContent-Type: image/jpeg\r\n">
}]
},"controller"=>"finished_guitars", "action"=>"create"} permitted: false>
my controller:
class FinishedGuitarsController < ApplicationController
def index
#finished_guitars = FinishedGuitar.all
end
def show
#finished_guitar = FinishedGuitar.find(params[:id])
end
def new
#finished_guitar = FinishedGuitar.new
#attachments = #finished_guitar.attachments.build
end
def create
#finished_guitar = FinishedGuitar.new(finished_guitar_params)
if #finished_guitar.save
unless params[:attachments].nil?
params[:attachments]['image'].each do |a|
#finished_guitar = #finished_guitar.attachments.create!(:image => a, :finished_guitar_id => #finished_guitar.id)
end
end
render json: { finishedGuitardId: #finished_guitar.id, attachments: #finished_guitar.attachments_attributes }, status: 200
else
render json: { error: #finished_guitar.errors.full_messages.join(", ") }, status: 400
end
end
private
def finished_guitar_params
params.require(:finished_guitar).permit(:title, :description, attachments_attributes: [:id, :image, :finished_guitar_id])
end
end
UPDATE
I am just adding the _form.html.erb
<div class="content">
<%= simple_form_for #finished_guitar, html: {multipart: true, id: "my-dropzone", class: "dropzone" } do |f| %>
<%= f.input :title %>
<%= f.input :description %>
<div class="dz-message needsclick">
<h3>Drop file here</h3> or
<strong>click</strong> to upload
</div>
<div class="fallback">
<br><br>
<%= f.simple_fields_for :attachments do |ff| %>
<%= ff.input_field :image, as: :file, multiple: true, name: "finished_guitar[attachments_attributes][][image]" %>
<% end %>
</div>
<br><br>
<%= f.button :submit, class: "btn btn-primary" %>
<% end %>
</div>
I can upload my files if I remove "my-dropzone", class: "dropzone"from <%= simple_form_for #finished_guitar, html: {multipart: true, id: "my-dropzone", class: "dropzone" } do |f| %>

Answer 1

It says name=params[attachments][][image], it seams you have something like:
params[:params][:attachments]
I'd recommend you to use rails-pry or byebug, stop the execution inside the action and you can easilly inspect the params hash and do thing like params.keys or params[:params] to see what's actually there