Starting a new shopify session from shopify_token and shopify_domain?

Question

I have a user_id attached to the Store model for a Shopify App. I want to be able to have a user login with their user account to have the shopify session start instead of using needing to open the app from their app section of their store. This is a standalone app btw.

I have tried this for when users sign in:

if Shop.find_by(user_id: current_user)
  shop = Shop.find_by(user_id: current_user)
  shop = ShopifyAPI::Session.new(shop.shopify_domain, shop.shopify_token)
  ShopifyAPI::Base.activate_session(shop)
end

and:

if Shop.find_by(user_id: current_user)
  shop = Shop.find_by(user_id: current_user)
  shop = ShopifyApp::SessionRepository.retrieve(shop.id)
  ShopifyAPI::Base.activate_session(shop)
end

I tried this in my session create method and as a after_action callback for the create method in the sessions controller...

Is there something I am doing wrong?

I tested this in console to make sure all of the assocations were correct. The token and shopify_domain are all there attached to the user