Uncodemy Alumni Story: From Fresher to Python Developer

# Expense Tracker API

## Problem
Small teams track shared expenses in spreadsheets and lose entries.

## What it does
- Users, groups and expenses with Django REST Framework
- Splits an expense equally or by custom shares
- Monthly summary endpoint per group

## Tech
Python 3.12, Django, Django REST Framework, PostgreSQL, pytest

## Run locally
python -m venv .venv && source .venv/bin/activate
pip install -r requirements.txt
python manage.py migrate
python manage.py runserver

## One problem I solved
Rounding made splits differ by 1 paisa. I stored amounts as
integers in paise and gave the remainder to the payer.

## Tests
pytest -q

# splits.py - small, readable, tested logic interviewers like to see
from typing import Dict, List


def split_equally(amount_paise: int, members: List[str], payer: str) -> Dict[str, int]:
    """Split an amount in paise; the payer absorbs any remainder."""
    if not members:
        raise ValueError("members cannot be empty")
    if payer not in members:
        raise ValueError("payer must be a member")
    share, remainder = divmod(amount_paise, len(members))
    result = {m: share for m in members}
    result[payer] += remainder
    return result


def test_split_equally_remainder_goes_to_payer():
    out = split_equally(1000, ["a", "b", "c"], payer="a")
    assert out == {"a": 334, "b": 333, "c": 333}
    assert sum(out.values()) == 1000

# Q: Return the first non-repeating character in a string, or None.
from collections import Counter
from typing import Optional


def first_unique_char(s: str) -> Optional[str]:
    counts = Counter(s)
    for ch in s:
        if counts[ch] == 1:
            return ch
    return None


assert first_unique_char("swiss") == "w"
assert first_unique_char("aabb") is None
assert first_unique_char("") is None

# Say out loud: O(n) time, O(k) extra space for k distinct characters.
# Mention the edge cases you tested: empty string, all repeating.

-- Q: Show each customer's name and total order value,
-- including customers with no orders (total = 0).
SELECT c.name,
       COALESCE(SUM(o.amount), 0) AS total_amount
FROM customers AS c
LEFT JOIN orders AS o
       ON o.customer_id = c.id
GROUP BY c.id, c.name
ORDER BY total_amount DESC;

-- Follow-up often asked: why LEFT JOIN and not INNER JOIN?
-- INNER JOIN would drop customers who have no orders.

# Typical first-week setup for a Python service
git clone git@github.com:<company>/orders-service.git
cd orders-service

python3 -m venv .venv
source .venv/bin/activate
pip install -r requirements.txt -r requirements-dev.txt

# Copy the sample settings, never commit real secrets
cp .env.example .env

# Run the tests first: they show how the code is meant to work
pytest -q

# Start the app
python manage.py runserver

# Save what worked
echo "setup: venv, pip install, cp .env.example, pytest" >> ~/notes/orders-service.md

# Ticket: reject orders with quantity <= 0
git switch main && git pull
git switch -c fix/order-quantity-validation

# 1. Write a failing test first
# tests/test_orders.py
# def test_quantity_must_be_positive(client):
#     resp = client.post("/api/orders/", {"item": 1, "quantity": 0})
#     assert resp.status_code == 400

# 2. Make the smallest change that fixes it, run tests
pytest tests/test_orders.py -q

# 3. Small commit, clear message, open a PR
git add -A
git commit -m "Validate that order quantity is positive"
git push -u origin fix/order-quantity-validation
# PR description: what, why, how tested, screenshots if UI

PROJECT STORY (practise saying this in about 5 minutes)

Project name : ______________________
Problem      : Who had what problem?
My role      : Solo / team of __, my part was ______
Tech choices : Python + ______ because ______
Hardest part : What broke, how I found the cause
Fix          : What I changed and how I tested it
If I had more time: one improvement I would make
Link         : github.com/<you>/<repo>

Likely follow-ups to prepare:
- Why this database / framework?
- How did you test it?
- What happens if two users do X at the same time?
- What would change if it had many more users?

OFFER CHECKLIST (confirm in writing before accepting)

Role
[ ] Job title and the team I will join
[ ] Main technologies I will work with
[ ] Is there a training or probation period? How long?

Terms
[ ] Compensation breakdown understood (fixed vs variable)
[ ] Joining date and location / work-from-office policy
[ ] Any service agreement or bond - read every clause
[ ] Notice period during and after probation

Check
[ ] Company details verified from official sources
[ ] Never pay any fee to receive a job offer
[ ] Offer letter received on company email domain

WEEKLY WORK LOG - first three months

Week: ____

Done
- Tickets closed: ______
- PRs merged: ______

Learned
- One new thing about the codebase: ______
- One new tool or command: ______

Review feedback
- Comment I received: ______
- What I will do differently: ______

Blocked on
- ______ (asked ______ on ______)

Next week
- One goal: ______

Use this log in one-to-ones with your manager.