validate-promo-codes

Validating Promo Codes

This Spin application illustrates how one could validate promo codes stored in a Key Value Store.

The application exposes three endpoints:

• POST /validate/:code - to validate a code
• POST /apply/:code - to apply a code
• POST /seed-promocodes - to generate 50 promo codes

Each promo code has the following properties

• Code: The actual promo code
• ValidFrom: A date when the promo code becomes valid
• ValidTo: A date when the promo code becomes invalid again
• Discount: Discount (percentage) value between 0.00 and 0.35
• Used: A boolean that will be toggled if the code has already been applied

Validation Logic

• A promo code could only be applied once
• A promo code is neither valid nor could it be applied if ValidFrom has not been reached
• A promo code is neither valid nor could it be applied if ValidTo has passed

Running the Spin App on your local machine

Compile the application by running spin build. Once compilation has finished, run the app with spin up:

spin build
spin up

Generating Promo Codes

To generate promo codes, send a POST request to /seed-promocodes:

curl -iX POST http://localhost:3000/seed-promocodes

HTTP/1.1 201 Created
content-type: application/json
content-length: 8408
date: Fri, 24 Jan 2025 14:51:10 GMT

[
  {
    "code": "83435dd4-6226-4d6c-afd4-2eb2cb7547d6",
    "validFrom": "2025-02-14T00:00:00Z",
    "validTo": "2025-08-14T00:00:00Z",
    "discount": 0.2684043
  },
   ...
]

The command above, will generate 50 random promo codes and store them in Key-Value Store. Additionally, all promo codes and their metadata will be returned as HTTP response (JSON).

Validating a Promo Code

Grab different UUIDs from the response received in the previous step and send a POST request to /validate/:code:

curl -iX POST http://localhost:3000/validate/0cde9a1e-09b4-4089-ab56-01c6f76ac31d
HTTP/1.1 200 OK
content-type: application/json
content-length: 114
date: Fri, 24 Jan 2025 15:09:30 GMT

{
  "code": "0cde9a1e-09b4-4089-ab56-01c6f76ac31d",
  "isValid": true,
  "reason": "",
  "discount": 0.33410984
}

Apply a Promo Code

Once you found a valid promo code, apply it by sending another POST request, this time, use the /apply/:code route:

curl -iX POST http://localhost:3000/apply/0cde9a1e-09b4-4089-ab56-01c6f76ac31d
HTTP/1.1 200 OK
content-type: application/json
content-length: 114
date: Fri, 24 Jan 2025 15:09:37 GMT

{
  "code": "0cde9a1e-09b4-4089-ab56-01c6f76ac31d",
  "isValid": true,
  "discount": 0.33410984
}

Once applied, you can try re-validating and re-applying to verify the code is treated as invalid.