cannot update attribute within users model in custom action - ruby-on-rails

Question

I am using the Gem Devise for users in my application. I added the role attribute within users that is set to nil. After I sign in, within the application controller I have a redirect that goes to a custom action within the users controller and view called binary_selection if current_user.role = nil. The code is below
application_controller.rb:
def after_sign_in_path_for(resource)
if current_user.role.nil? ## temporary solution
#update_path(resource)
binary_selection_path(resource)
else
root_path(resource)
end
end
users_controller.rb:
def binary_selection
#user = current_user
respond_to do |format|
if #user.update_attributes(params[:user][:role])
format.html { redirect_to root_url, notice: "#{#user.name} was updated." }
else
format.html { render action: "edit" }
end
end
end
views/users/binary_selection.html.erb:
<%= form_for #user, url: binary_selection_path(#user), html: { method: :patch } do |f|
%><%= current_user %>
<div class = "form-group">
<%= f.label :role %>
<%= f.text_field :role, class: 'form-control', placeholder: "Enter wiki title", id: 'wiki_title' %>
</div>
<div class = "form-group">
<%= f.submit class: 'btn btn-success' ,id: 'wiki_submit' %>
</div>
<% end %>
config/routes.rb:
Rails.application.routes.draw do
devise_for :users
get "/users" => "users#binary_selection", as: 'binary_selection'
resources :users
end
When I get redirected to the binary_selection view I get this error:
NoMethodError in UsersController#binary_selection
undefined method `[]' for nil:NilClass
where it highlights this line within the users controller:
if #user.update_attributes(params[:user][:role])
I also noticed it has this for the params on the error page:
{"format"=>"13"}

Answer 1

You redirect your user after sign_in to the binaray_selection_path. This will result in a HTTP GET request. In your users_controller you try to get a attribute from the params that simple does not exist. There is no params[:user], because the form was not sent yet.
You need to redirect the user to a page were the form is rendered.
I advise to read this guide: http://guides.rubyonrails.org/getting_started.html#getting-up-and-running

Answer 2

Your form is not submitting the values properly may be. So inspect your params in the binery select action.
record#update_attributes doesn't take a single value, it accepts hash. So the proper code should be something like:
rails version < 4
if #user.update_attributes(params[:user])
in rails 4.*
if #user.update_attributes(user_params)
in controller make sure you have permitted the user parameters.