DEV Community

Cover image for SaaS: How to code the subscriptions business model. Elementary level
Yaroslav Shmarov
Yaroslav Shmarov

Posted on • Updated on • Originally published at blog.corsego.com

SaaS: How to code the subscriptions business model. Elementary level

Software as a Service (SaaS) = leasing = access to software with an end date.

Client is charged to postpone the end date.

From this perspective, a "One-time payment" = subscription with lifetime access.

Minimalistic Database representation:

subscription uml

Example: Spotify subscription

In this case a user can buy a premium subscription for $12,11 for a limited time 1 month to remove adds.

Here's how it will work:

# user.rb

#  email      :string
#  ends_at    :datetime

def premium_price
  # how much to charge for postponing ends_at
  # always keep money in integer. last 2 digits are cents
  1299.to_i 
end

def premium_interval
  # by how long to postpone the ends_at
  # monthly or yearly or forever
  1.month 
end

def active_subscription?
  ends_at > Time.now
end

def show_annoying_adds?
  # business logic
  unless active_subscription?
end
Enter fullscreen mode Exit fullscreen mode
# charge.rb

# user_id     :integer
# amount      :integer # to track how much was paid at this moment of time

belongs_to :user
Enter fullscreen mode Exit fullscreen mode
# charges_controller.rb

def create
  @charge.amount = current_user.premium_price

  # PAYMENT PROVIDER LOGIC GOES HERE

  if @charge.save
    current_user.update(ends_at: Time.now + current_user.premium_interval)
  end
end
Enter fullscreen mode Exit fullscreen mode

This way whenever a user makes a payment and creates a charge,
his subscription ends_at is set to a later date based on premium_interval.

Of course, in this simple example charges are not automatic and the user has to explicitly create a charge.

That's it! 🤠

Liked this article? Please follow me! It will really motivate me to post more fun stuff!

Top comments (0)