01-rest-api

01 — REST API

A minimal REST API with two routes: GET /workouts returns a list of workouts, POST /workouts accepts a new one and echoes it back. Built with Flask. No database yet — the data lives in memory and resets when the app restarts (that's what later concepts fix).

Run it

From the repo root, with your virtual environment activated:

cd 01-rest-api
pip install -r requirements.txt
python app.py

Then open http://127.0.0.1:5000/workouts in your browser — you'll see the list of workouts as JSON. That's the GET route working.

Test the POST route

A browser can only send GET requests by typing a URL, so to test POST /workouts you need to send a request from the command line. Leave the app running in one terminal and open a second one.

On Windows (PowerShell):

Invoke-RestMethod -Uri http://127.0.0.1:5000/workouts -Method Post -ContentType "application/json" -Body '{"sport": "swim", "distance_km": 0.4}'

On macOS / Linux (curl):

curl -X POST http://127.0.0.1:5000/workouts \
  -H "Content-Type: application/json" \
  -d '{"sport": "swim", "distance_km": 0.4}'

Both send a workout as JSON and should get the same workout echoed back. The Content-Type: application/json header is required — it's what tells Flask the body is JSON so request.get_json() will parse it. Leave it out and the request body comes back empty.

What I learned

I learn how to scaffold a Flask app. I was familiar with REST, but I learnt to write out a GET and POST request for a sports tracker API. I experimented with lists and later converted them into dictionaries to optimize for the JSON format. What's the difference between request.get_json() and jsonify()? What does if __name__ == "__main__": actually decide? The data-modelling bit: why store numbers as numbers, not "6km"?

Concepts touched

Flask routes, HTTP methods (GET/POST), request bodies, JSON responses, basic data modelling.