Update User Outside `users#edit` Page - ruby-on-rails

Question

I am trying to create a simple button that updates the boolean user attribute notify_generator from its default value of false to true when the user submits a form. The form is on my home#construction page:
<% if current_user.notify_generator == false %>
<h1 class="">Want to know when it's ready?</h1>
<%= form_for(#user) do |f| %> <<<<<<ERROR CALLED ON THIS LINE
<%= f.hidden_field :notify_generator, value: true %>
<%= f.submit "Keep Me In The Loop", class: "btn btn-primary" %>
<% end %>
<% else %>
<h1>You're set! We'll let you know when the generator is up and running!</h1>
<% end %>
The home_controller is as follows:
class HomeController < ApplicationController
before_action :historical_only
skip_before_action :historical_only, except: [:history]
before_action :authenticate_user!, only: [:construction, :generator]
def index
end
def history
end
def about
end
def gear
end
def generator
end
def construction
#user = current_user
end
private
def historical_only
unless current_user && ( current_user.access_historical == true || current_user.admin == true )
flash[:error] = "You must be a historical BurnIt member to see those goodies."
render action: "index"
end
end
end
Right now, when I try to access the home#construction page I get undefined method 'user_path' for #<#<Class:0x007fbc236054a0>:0x007fbc24495470>. I think this is symptomatic for trying to update a user from outside the domain of the registrations controller. I'm using the devise gem, if that makes a difference.
Can anyone see where I'm going wrong here?
ADDITIONAL INFORMATION:
new_user_session GET /users/sign_in(.:format) devise/sessions#new
user_session POST /users/sign_in(.:format) devise/sessions#create
destroy_user_session DELETE /users/sign_out(.:format) devise/sessions#destroy
user_password POST /users/password(.:format) devise/passwords#create
new_user_password GET /users/password/new(.:format) devise/passwords#new
edit_user_password GET /users/password/edit(.:format) devise/passwords#edit
PATCH /users/password(.:format) devise/passwords#update
PUT /users/password(.:format) devise/passwords#update
cancel_user_registration GET /users/cancel(.:format) registrations#cancel
user_registration POST /users(.:format) registrations#create
new_user_registration GET /users/sign_up(.:format) registrations#new
edit_user_registration GET /users/edit(.:format) registrations#edit
PATCH /users(.:format) registrations#update
PUT /users(.:format) registrations#update
DELETE /users(.:format) registrations#destroy

Answer 1

You have 2 choices: You can either either define your own UsersController, or you can use Devise's existing RegistrationsController.
I won't explain how to implement UsersController--that's standard MVC and I'm sure you've done it before.
But if you want to leverage existing devise code, let's take a look at how devise does this here:
<%= form_for(resource, as: resource_name,
url: registration_path(resource_name), html: { method: :put }) do |f| %>
Notice that you need to pass the option url: registration_path(resource_name). In this case, that resolves to user_registration_path, so you can just use url: user_registration_path. The resource part is specific to devise controllers--because you're using #user instead, you don't need the as: resource_name because Rails can infer that the resource name is user from the name of the instance variable (#user).
You will probably need to customize your permitted parameters. See the devise README for how to do this.