mikekauffman / lifetime-value

A Rails app / challenge designed to include both interesting ruby _and_ Rails code

Lifetime Value

Setup

• bundle
• rake db:create db:migrate db:seed
• rails s

You can run specs with:

• rspec

Note: email/password combinations for existing users populated by rake db:seed can be found in the db/seeds.rb file.

Current Subscribers

This app tracks subscriptions.

When a user subscribes, it adds a row to the subscription_events table that looks like this:

user_id	date	event_type	price_per_month_in_cents

  2 | 2014-06-01 | subscribed |                      700

When user unsubscribes, it adds a row to the subscription_events table that looks like this:

user_id	date	event_type	price_per_month_in_cents

  2 | 2014-06-01 | unsubscribed |                         

From this, we can say that a user is subscribed if their most recent subscription event is "subscribed". For example, users 2 and 3 below would both be subscribed:

user_id	date	event_type	price_per_month_in_cents

  2 | 2014-05-01 | subscribed    |                       700
  3 | 2014-03-01 | subscribed    |                      1200
  3 | 2014-04-01 | unsubscribed  |                          
  3 | 2014-05-01 | subscribed    |                       500

Whereas in the example below, user 5 would not be subscribed:

user_id	date	event_type	price_per_month_in_cents

  5 | 2014-04-01 | subscribed    |                       700
  5 | 2014-05-01 | unsubscribed  |                          

Lifetime Value

Users can subscribe with different amounts / month. When a user subscribes, it says the amount that they will pay per month. In addition to unsubscribing, the subscription_events table can also show that a user's subscription price has changed. For example, this user paid $7.00 for January, and $4.00 for February.

user_id	date	event_type	price_per_month_in_cents

  5 | 2014-01-01 | subscribed    |                       700
  5 | 2014-02-01 | changed       |                       400

If today's date is 2014-03-01, then the lifetime value of the user above would be $11.00.

If today's date is 2014-04-01, then the lifetime value of the user would be $15.00

($7 * 1 month) + ($4 * 2 months) == $15

Stories

Site administrators can see who the current members are

When I login
I should be able to click a "Current Members" link
And see a table that lists all users who are current subscribers
And the list should be sorted by name

Users can see the lifetime value of each user

When I login
I should be able to click a "Lifetime Value" link
And see a table that lists all users
And next to each user I should be able to see their lifetime value
And the rows should be sorted by the lifetime value (highest first)

Checking your work

To check your work:

• Run rake db:seed again to make sure your data was generated the same day you are checking
• Go to your web page
• Compare the results to these answers

Think about it

• How well would your code fare if you had to pull data from an JSON API, instead of from the database?
• Do you have to create SubscriptionEvent objects in your specs? If so, can you figure out a way to just instantiate them (instead of saving them to the database)?
• Do you have to require rails_helper for your specs, or can you just require spec_helper?

Wireframes

Current Members

Lifetime Value