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:

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 

# charge.rb # user_id :integer # amount :integer # to track how much was paid at this moment of time belongs_to :user 

# 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 

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! 🤠

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