Checkout basket

The situation

You’re working on an online shopping platform. The sales team wants to know which items were added to a basket, but removed before checkout. We will use this data later for targeted discounts.

The task

Build a shopping basket that helps you get this data.

The solution

I have created an API-only rails app that resembles a shopping basket. It follows a simple flow. For the links below to work make sure that the documentation has been generated.

User flow

• user visits the home page where they find a list products and at that time a checkout session is also created.

• user adds products to the basket by calling the add_product

  • a new model in checkout products is created which contains the checkout session id and the product id. This is where we also keep the removed status which is a timestamp field called removed_at and from that we assume that if the field is populated the product is marked as removed

• user decides to remove a product from the basket (checkout_products) then the remove_product endpoint is called marking it as removed by populating the removed_at field with the current time.

• after the user has finished shopping they arrive at the checkout where they can view all the products they have added, excluding the ones they removed, to the basket during this session.

• Once they 'pay' the session is complete and the checkout_complete endpoint is called, making it impossible to add or remove any more products from that session.

Sales team user flow

The sales team has a list of reports they can use in order to retrieve the customer shopping data and make the right decisions

• count_removed_products will return a list of products that were removed starting from the most expensive one

[
  {
    "amount_removed": 2,
    "product_name": "product_37",
    "product_price": 370
  },
  {
    "amount_removed": 5,
    "product_name": "product_36",
    "product_price": 360
  },
  {
    "amount_removed": 5,
    "product_name": "product_35",
    "product_price": 350
  }
]

• products_grouped_by_session will return a list of all products grouped by session by passing the optional param removed_status they can filter the list to see all, removed or not_removed each list of products is sorted by most expensive

{
  "zNZb3sFFivA98MkYwXsEQw": {
    "token": "zNZb3sFFivA98MkYwXsEQw",
    "started_at": "2021-10-14T14:26:41.903Z",
    "ended_at": "2021-10-14T14:26:42.958Z",
    "products": [
      {
        "product_name": "product_37",
        "product_price": 370,
        "added_at": "2021-10-14T14:26:42.858Z",
        "removed_at": "2021-09-07T14:26:42.857Z"
      }
    ]
  }
}

• products will return a list of all products by passing the optional param removed_status they can filter the list to see all, removed or not_removed starting from the most expensive one

[
  {
    "product_name": "product_39",
    "product_price": 390,
    "added_at": "2021-10-14T14:05:33.369Z",
    "removed_at": null
  }
]

Local installation

In order to run the app locally you will need ruby 3.0.0 installed preferably via a version manager like rbenv. also postgres as a db with the user credentials found the in the /config/database.yml file. In a production environment the credentials are either encrypted by using the rails built-in encrypted credentials feature or by using ENV variables managed with a gem like dotenv and can be found in an .env file. Personally i prefer using encrypted credentials as it allows you to keep them under version and the only thing you need to worry about is having the key in place either stored in a .key file or as a ENV[RAILS_MASTER_KEY] variable. A visual schema for the database can be found under /schema.xml

Once that is sorted out we can run the following commands to get up and running

bundle install
rails db:schema:load
rails s

Test suite

For testing Rspec was used coupled with factory_bot for test setups and simplecov for measuring the code test coverage which is currently at 100%.

To run the tests we need to run the following commands

rspec

API documentation generation

In order to generate the documentation for the endpoints the apipie gem was used which generates documentation by parsing the tests but also the routes.rb file. In order to generate the docs locally run APIPIE_RECORD=examples rspec and then navigate to http://localhost:3000/apipie

Swagger

apipie can also generate swagger compatible documentation by running rake apipie:static_swagger_json which can be viewed by navigating to /doc/swagger/index.html