💸 Transaction Processor API

A Django REST-based service that receives transaction webhooks from external payment processors (e.g., RazorPay), acknowledges them instantly, and processes them asynchronously with a simulated delay.

Live Demo:
🌐 https://transaction-processor-api-6.onrender.com/ [Please use Postman for accurate API testing.]

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🧾 Overview

This API receives webhook notifications, stores transaction details, and processes them in the background.
It ensures:

• Fast acknowledgments (< 500ms)
• Background processing (simulated 30-second delay)
• Duplicate prevention (via unique transaction_id)
• Persistent data storage
• Cloud deployment (Render)

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✅ Implemented Endpoints

Method	Endpoint	Description
GET	/	Health check
POST	/v1/webhooks/transactions	Accepts new transaction webhook
GET	/v1/transactions/{transaction_id}	Retrieve transaction status

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🧪 How to Test the API (Step-by-Step)

Use Postman or curl.
Browser-only testing will not show POST results correctly.

🔹 Step 1: Health Check

Request GET https://transaction-processor-api-6.onrender.com/

Expected Response

{ "status": "HEALTHY", "current_time": "2025-11-01T12:34:56Z" }

✅ Confirms the app is live and reachable.

🔹 Step 2: Send a Webhook Request

[ 1. Below URL paste it into Postman URL With POST request ]

POST https://transaction-processor-api-6.onrender.com/v1/webhooks/transactions

[2. Under Body select JSON and type context ]

{ "transaction_id": "txn_1009", "source_account": "acc_user_789", "destination_account": "acc_merchant_456", "amount": 1500, "currency": "INR" }

Expected Response :

{ "message": "Accepted for processing", "transaction_id": "txn_1009" }

📈 HTTP Status: 202 Accepted ⚡ Response Time: under 500 ms 💡 The background process now runs for ~30 seconds.

🔹 Step 3: Check Processing Status After ~30 seconds, check the status:

Request

[ Put this URL in Postman with GET request for checking Status ]

GET https://transaction-processor-api-6.onrender.com/v1/transactions/txn_1009

Expected Response (after 30 seconds)

{ "transaction_id": "txn_1009", "source_account": "acc_user_789", "destination_account": "acc_merchant_456", "amount": 1500.0, "currency": "INR", "status": "PROCESSED", "created_at": "2025-10-31T20:05:39.167538Z", "processed_at": "2025-10-31T20:06:09.175100Z" }

If called before 30s, status will show "PROCESSING" and "processed_at": null.

🔹 Step 4: Duplicate Webhook Prevention Re-send the same webhook request (txn_1009 again). You’ll still get a 202 Accepted, but the system will not duplicate records.

Each transaction_id is unique.

Repeated webhooks are gracefully ignored.

🔹 Step 5: Example of an Already Processed Transaction You can view this sample transaction:

GET https://transaction-processor-api-6.onrender.com/v1/transactions/txn_1004 Example Response

{ "transaction_id": "txn_1004", "source_account": "acc_user_789", "destination_account": "acc_merchant_456", "amount": 1500.0, "currency": "INR", "status": "PROCESSED", "created_at": "2025-10-31T20:05:39.167538Z", "processed_at": "2025-10-31T20:06:09.175100Z" } ⚙️ Example cURL Commands Health Check

curl -i https://transaction-processor-api-6.onrender.com/ Send Webhook

curl -i -X POST https://transaction-processor-api-6.onrender.com/v1/webhooks/transactions
-H "Content-Type: application/json"
-d '{"transaction_id":"txn_1009","source_account":"acc_user_789","destination_account":"acc_merchant_456","amount":1500,"currency":"INR"}' Check Status (after 30s)

curl -i https://transaction-processor-api-6.onrender.com/v1/transactions/txn_1009

🧰 How to Run Locally Clone Repo

git clone https://github.com/codingwithrsn33/transaction-processor-api.git cd transaction-processor-api Create Virtual Environment

python -m venv env source env/bin/activate # (Mac/Linux) env\Scripts\activate # (Windows) Install Dependencies

pip install -r requirements.txt Apply Migrations

python manage.py makemigrations python manage.py migrate Run Development Server

python manage.py runserver Test Locally

Visit http://127.0.0.1:8000/ → health check

Use Postman to test same endpoints locally.

🧠 Technical Choices

Feature Technology Reason

Framework Django + Django REST Framework Fast, reliable API development

DB SQLite Lightweight, persistent local DB

Background Tasks Thread-based async delay Simulates real async (Celery )

Deployment Render.com Free cloud hosting, simple setup

Idempotency Unique transaction_id check Prevents duplicates

Logging Django default + print statements Simple monitoring

🧩 Key Requirements Covered

✅ Fast Response (<500ms) on webhook receive ✅ Background Processing (30s delay) ✅ Persistent Storage ✅ Idempotency (no duplicates) ✅ Health Check Endpoint ✅ Public Cloud Deployment ✅ Test Instructions & README Provided

🚀 Quick Verification Checklist (for reviewers) Test Expected Outcome GET / Returns status: HEALTHY POST /v1/webhooks/transactions Returns 202 Accepted instantly Wait 30s + GET /v1/transactions/{id} Shows status: PROCESSED Duplicate POST No duplicate record created Render link works 24x7 ✅

🧩 Troubleshooting Issue Cause Fix transaction_id is required Missing JSON or Content-Type Set header Content-Type: application/json DisallowedHost Render host missing from ALLOWED_HOSTS Added "*" in settings Response delay >500ms Network lag or free-tier wake-up time Retry after app wakes up Empty result on /v1/transactions/{id} Queried before processing completed Wait 30s and retry

💬 Final Note Please test using Postman as per the above instructions. The API is live and publicly hosted at:

👉 https://transaction-processor-api-6.onrender.com/

You can verify health, send webhooks, and check the transaction status after ~30 seconds to confirm background processing.

🧱 Author

Rohan Subhash Darekar Python | Django | REST APIs | SQL | Cloud Deployment 📍 Built for Backend Developer Assessment GitHub: codingwithrsn33