Mini project: a study-session tracker

A small complete program is a chance to connect ideas rather than learn another isolated syntax feature.

What you will learn

Design a small data record
Write and call a helper function
Persist a result and verify its output

Define a small goal

This project records one topic and a positive number of minutes. It intentionally avoids accounts, network access, and a large interface: the goal is to practise the Python ideas from earlier lessons. Write down the expected input and output first, then separate the calculation from the formatting.

Keep the calculation reusable

A function can validate a duration and return a record that another part of the program stores. Use a list when you later want to keep several records in memory, and a dictionary when each record has named fields. Simple data structures make the first version easier to inspect.

Persist only what you need

The example uses JSON to write a small record into a temporary directory. JSON represents common data such as strings, numbers, lists, and dictionaries. A temporary file makes the example safe to run repeatedly; a real tracker would need a deliberate location and a plan for preserving earlier sessions.

Test normal and invalid cases

Run the program with a positive duration, then try zero or text. A useful program states its rule and does not save an invalid record as if it were valid. Change one thing at a time, read the result, and keep the example small enough that you can explain each statement.

import json
from pathlib import Path
from tempfile import TemporaryDirectory

def make_session(topic, minutes):
    if minutes <= 0:
        raise ValueError('minutes must be positive')
    return {'topic': topic, 'minutes': minutes}

with TemporaryDirectory() as folder:
    path = Path(folder) / 'session.json'
    session = make_session('Python', 25)
    path.write_text(json.dumps(session), encoding='utf-8')
    saved = json.loads(path.read_text(encoding='utf-8'))
    print(f"{saved['topic']}: {saved['minutes']} minutes")

Expected output

Python: 25 minutes

Practice exercise

Extend the project to keep two session records in a list and print their total minutes.

Show a hint

Sum the minutes values from each dictionary.

Show one possible solution

Create a list of two make_session results and calculate sum(session['minutes'] for session in sessions) before printing it.

Quick check

Why does make_session reject zero minutes? The project defines a session as requiring a positive duration Python cannot store zero

Frequently asked questions

Can I keep adding sessions to the JSON file?

<p>Yes, but the program must read the existing list, add a validated record, and write the updated data deliberately. The example replaces a temporary file to keep each run predictable.</p>