Creating a nested resource in Rails 5 - ruby-on-rails

Question

I am trying to create a nested resource so that products can have notes associated with them. I have set up the associations within the model etc, but when I try to use the form to create a new note, I get the following error:
NoMethodError in Notes#create
Showing /Users/myusername/myapp/app/views/notes/_form.html.erb where line #2 raised:
undefined method `notes_path' for #<#<Class:0x00007fb3630b1ad0>:0x00007fb361eab868>
This is the line it is referring to:
<%= simple_form_for [#product, #note] do |f| %>
This are the new & create actions in the notes controller:
def new
#product = Product.find(params[:product_id])
#note = #product.notes.build
end
def create
#note = Note.new(product: #product)
respond_to do |format|
if #note.save
format.html { redirect_to product_notes, notice: 'Note was successfully created.' }
else
flash.now[:error] = "It doesnt work"
render 'new'
end
end
end
and the form partial:
<%= simple_form_for [#product, #note] do |f| %>
<%= f.error_notification %>
<%= f.error_notification message: f.object.errors[:base].to_sentence if f.object.errors[:base].present? %>
<div class="form-inputs">
<%= f.input :content %>
<%= f.input :author %>
<%= f.check_box :visible %>
</div>
<div class="form-actions">
<%= f.button :submit %>
</div>
<% end %>
I am going round in circles with making changes, and cannot seem to find any documentation on nested resources that isn't deprecated. Can anybody assist, please?
Edited to add:
I changed my controller action to something based on PGill's answer and can now get the page to load without an action controller error. However, it now re-renders the new note form, with errors saying that the form fields cannot be blank. They were not blank when I submitted them - what's happening to cause this?
Updated controller action:
def create
#product = Product.find(params[:product_id])
#note = #product.notes.new
respond_to do |format|
if #note.save
format.html { redirect_to product_notes_path(#product), notice: 'Note was successfully created.' }
else
format.html { render :new, notice: 'Note failed to be created.' }
end
end
end
When I was previously getting errors, it had this as the request parameters, so they are getting passed?
Parameters:
{"utf8"=>"✓",
"authenticity_token"=>"lotsofletters",
"note"=>{"content"=>"test", "author"=>"test", "visible"=>"0"},
"commit"=>"Create Note",
"product_id"=>"1"}

Answer 1

Referring to your edit; of course you should get empty fields errors because you are creating a new object #note without providing any attributes for it:
#note = #product.notes.new
it should be like
#note = #product.notes.build(params[:note])
also take care to provide a sanitizer for note in notes controller :
private
def note_params
params.require(:note).permit(:content, :author, :visible, :product_id)
end
so your code in create will look like:
def create
#product = Product.find(params[:product_id])
#note = #product.notes.build(note_params)
respond_to do |format|
if #note.save
format.html { redirect_to product_notes_path(#product), notice: 'Note was successfully created.' }
else
flash.now[:error] = "It doesnt work"
render 'new'
end
end
end
private
def note_params
params.require(:note).permit(:content, :author, :visible, :product_id)
end

Answer 2

#product is nil in create
Your form is failing validations and rendering new
update the create action to
def create
#product = Product.find(params[:product_id])
#note = #product.notes.new
respond_to do |format|
if #note.save
format.html { redirect_to product_notes_path(#product), notice: 'Note was successfully created.' }
else
flash.now[:error] = "It doesnt work"
render 'new'
end
end
end
redirect_to should be product_notes_path(#product) notes#index