Nested resources in namespace form_for

Question

Problem

The form_for helper incorrectly determines the path to my nested resource inside of a namespace. The models in question are: Forum::

Answer 1

@Douglas: It's not working for me. In my view, the names in routes should be pluralize. When I do like recommended, the error is:

undefined method `admin_admin_person_admin_image_path' for #<#:0x55a9bc8>

My solution that worked for New:

form_for @image, url: admin_person_images_path(@person, @image)

My solution that worked for Edit:

form_for @image, url: admin_person_image_path(@person, @image)

Ist there any solution to combine this in one form?

Edit (Solution for a new nested namespaced route in a form):
Now I had the following logic in the routes.rb

resources :mobile_users do
 namespace :candystore do
  resource :transactions
 end
end

The form for new_mobile_user_candystore_transactions is

<%= form_for [@mobile_user], url: mobile_user_candystore_transactions_path(@mobile_user), method: :post do |f| %>

to get to the Candystore::TransactionsController create method and not to e.g the MobileUser create method or Candystore::TransactionsController update method.