Use Google::Auth::Stores::FileTokenStore with database - ruby-on-rails

Question

I'm trying to implement a 3 legged authentication in my app to the Google API, to be able to access registered users' Google Calendars.
In the quickstart Ruby guide, this command comes up that as far as I understand should point to the user's tokens:
token_store = Google::Auth::Stores::FileTokenStore.new(file: CREDENTIALS_PATH)
It expects the tokens stored in a file (or Redis), but (of course) I store each user's tokens in my database (Postgres).
Have I understand the purpose of the command wrongly or otherwise - how do I use it with a database store?
Official documentation

Answer 1

I implemented it myself based on #Rafe's answer. Just wanted to share in case someone wants to copy the ActiveRecord / Database store implementation:
module Google
module Auth
module Stores
class DatabaseTokenStore < Google::Auth::TokenStore
def load(id)
user = User.find(id)
{
"client_id": ENV['google_client_id'],
"access_token": user.token,
"refresh_token": user.refresh_token,
"scope": ENV['google_scopes'],
"expiration_time_millis": user.token_expires_at
}.to_json
end
def store(id, token)
user = User.find(id)
hsh = JSON.parse(token)
user.update(
token: hsh["access_token"],
token_expires_at: hsh["expiration_time_millis"] / 1000
)
end
end
end
end
end

Answer 2

Implement it yourself, according to the the readme:
Custom storage implementations can also be used. See token_store.rb for additional details.
It shouldn't be too hard to implement the load(id), store(id, token) and delete(id) with ActiveRecord (or another ORM) by the looks of the mentioned files.

Answer 3

Accepted answer above it's good and I recommend it https://stackoverflow.com/a/48267763/473040, but I find it useful to store everything for future debugging. Also simplicity is beautiful :)
Add json column to Postgres DB table (or serialise text field in other db)
class AddGooglePhotosTokensToUsers < ActiveRecord::Migration[7.0]
def change
add_column :users, :google_photo_tokens, :json
end
end
class:
class GoogleAuthDbStore < Google::Auth::TokenStore
def load(id)
user = User.find(id)
user.google_photo_tokens
end
def store(id, tokens)
user = User.find(id)
user.google_photo_tokens = tokens
user.save!
end
def delete id
user = User.find(id)
user.google_photo_tokens = nil
user.save!
end
end
use
def authorizer
return #authorizer if #authorizer
client = Google::Auth::ClientId.new(Rails.application.credentials.google.fetch(:client_id), Rails.application.credentials.google.fetch(:client_secret))
scope = ['https://www.googleapis.com/auth/photoslibrary.readonly']
token_store = Provider::GoogleAuthDbStore.new # <<<here
#authorizer = Google::Auth::WebUserAuthorizer.new(client, scope, token_store, '/auth/google/callback')
#authorizer
end