How to update a profile attribute by link_to - ruby-on-rails

Question

I want to update a Profile model attribute by using link_to. The Profile model have a lang column, and I want to change to :en.
I could find out that I should use method: :put.
<%= link_to t('english'), profile_path(profile: {lang: :en}), method: :put %>
But it's ends up with error:
ActionController::UrlGenerationError in StaticPages#home
Showing /Users/ironsand/dev/phrasebook/app/views/layouts/_header.html.erb where line #21 raised:
No route matches {:action=>"update", :controller=>"profiles", :profile=>{:lang=>:en}} missing required keys: [:id]
I have this line in routes.rb to use the path:
resources :profiles, only: :update
How can I enable the function like this?
I found a similar question, but the case is a bit difference.
Edit
class ProfilesController < ApplicationController
def update
return redirect_to root_path unless current_user # If user is not logged in, redirect to /
if current_user.profile.update(profile_params) # Don't forget about validation for lang in Profile model
redirect_to root_path
else
redirect_to root_path
end
end
private
def profile_params
params.require(:profile).permit(:lang)
end
end

Answer 1

You need to identify the profile somehow, that's why it asks for id. But you can update profile without id, you just need to improve update method:
def update
return redirect_to root_path unless current_user # If user is not logged in, redirect to /
if current_user.profile.update(profile_params) # Don't forget about validation for lang in Profile model
redirect_to success_path
else
redirect_to error_path
end
end
private
def profile_params
params.require(:profile).permit(:lang)
end
For route, try this:
resources :profiles, only: [] do
collection do
put :update
end
end
or just:
put '/profiles' => 'profiles#update'

Answer 2

Since you're updating a specific profile, you need to supply something that lets your controller know what profile you're updating.
As you can see from the error message generated, your controller can't identify which profile it is that you're asking to be updated. You need to supply the id of the profile in order to update it.
One way this could be achieved with link_to is as follows:
link_to t('english'), profile_path(id: #profile.id, lang: :en), method: :put
lang would then be available in your update action in params[:lang].