CryptoStock – API Aggregator with FastAPI & MongoDB

Overview

CryptoStock is a FastAPI-based web application that aggregates live cryptocurrency and stock market data into a single interface.
It connects to CoinGecko (for crypto) and Alpha Vantage (for stocks), with caching implemented in MongoDB (via TTL indexes) to reduce API calls and improve performance.
The project also includes a simple web UI where users can:

• Search for crypto prices
• Search for stock quotes
• Use a mixed search to compare both
• View price history graphs (30-day line charts)
• Manage results with caching (showing “miss” on first call, then “hit” within TTL)

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Features

• Crypto price search using CoinGecko API
• Stock quote search using Alpha Vantage API
• Mixed aggregator endpoint for combined results
• MongoDB caching with TTL (hit/miss visible in UI & API)
• UI with suggestions (typeahead for crypto & stock symbols)
• Price history charts (30 days, rendered with Chart.js)
• Request logging in Mongo (with 7-day TTL)
• Comprehensive backend tests using Pytest (see tests/ folder)

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Architecture

• FastAPI as the backend framework
• MongoDB (running in Docker) for caching & logs
• Adapters for each external API (CoinGecko, Alpha Vantage)
• Service layer (aggregator & cache service) shared by API and UI
• Templates (Jinja2 + Chart.js) for the web interface
• Tests (Pytest) for backend verification with mocked APIs

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Setup Instructions

1. Clone the repo

git clone https://github.com/gregfu05/api-aggregator.git
cd api-aggregator

2. Create and activate a virtual environment

python3 -m venv .venv
source .venv/bin/activate  # macOS/Linux
.venv\Scripts\activate     # Windows

3. Install dependencies

pip install -r requirements.txt

4. Environment variables

Create a .env file in the project root:

MONGODB_URL=mongodb://localhost:27017
MONGODB_DB=aggregator
ALPHAVANTAGE_API_KEY=your_alpha_vantage_api_key_here

Get a free Alpha Vantage API key at: https://www.alphavantage.co/support/#api-key

5. Run MongoDB with Docker

docker compose up -d

This starts MongoDB in a container named aggregator-mongo.

6. Initialize indexes (cache TTL + logs TTL)

python -m scripts.init_db

7. Start the FastAPI server

uvicorn app.main:app --reload

Access it at: http://127.0.0.1:8000

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Usage

API Endpoints

Endpoint	Description
GET /health	Check server status
GET /crypto/price?ids=bitcoin&vs=usd	Live crypto price
GET /stocks/quote?symbol=AAPL	Live stock quote
GET /aggregate?symbols=bitcoin,AAPL&window=60	Combine both with caching
GET /cache/status	Cache contents / status
GET /logs/status	Recent request logs

Interactive docs:

• Swagger UI → http://127.0.0.1:8000/docs
• ReDoc → http://127.0.0.1:8000/redoc

Web UI

Visit:

• /crypto → crypto search (with suggestions + chart)
• /stocks → stock search (with suggestions + chart)
• / → mixed search for both crypto & stocks (with overlay chart)

The UI displays cache results: miss on first call, hit on repeat (within TTL).

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Tests

This project includes a complete backend test suite (tests/ folder) written in Pytest.
The tests mock external API calls (CoinGecko & Alpha Vantage) and use an in-memory cache to simulate MongoDB.

Run Tests

pytest -q

or for more detailed insights

pytest -q -vv

Test Coverage

• /health endpoint
• /aggregate cache (hit/miss logic)
• /history/crypto and /history/stock (mocked 30-day data)
• In-memory caching system functionality

Example Output

$ pytest -q
....                                                                                        [100%]
4 passed in 2.5s

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Development Notes

• Mongo cache TTL configurable via window parameter (default 60s).
• Request logs stored in Mongo with a 7-day TTL (req_logs collection).
• Modular code structure: adapters, services, routes, templates, tests.
• Git commits are meaningful and descriptive to track incremental progress.

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License

This project is for academic purposes at IE University.