Habit Tracker (Python, SQLite, SQLAlchemy)

This project was developed as part of the IU module
Object-Oriented and Functional Programming with Python (DLBDSOOFPP01)

A small, robust habit tracker with clear domain logic, daily/weekly period handling, streak analytics, and a simple CLI.
Data is persisted in SQLite via SQLAlchemy 2.0.

Table of Contents

• Features
• Setup
• Usage
• Example Output
• Tests
• Roadmap

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Features

• Create and list habits (filter by periodicity)
• Check-offs with normalized period bounds (day / ISO week)
• View which habits are due today/this week
• Longest streak analytics (per habit or best overall)
• Export habits and checks to JSON and CSV

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Setup

Clone or download this repository, then install dependencies:

python -m pip install -r requirements.txt

# Add and list
python -m habits.cli add "Drink water" --periodicity daily
python -m habits.cli list

# List only weekly habits
python -m habits.cli list-by --periodicity weekly

# Check now (marks as done for the current period)
python -m habits.cli check "Drink water"

# Show which habits are due
python -m habits.cli due

# Streaks
python -m habits.cli streak "Drink water"
python -m habits.cli streak-all

# Export data
python -m habits.cli export-habits --format json --path export/habits.json
python -m habits.cli export-checks --format csv  --path export/checks.csv
python -m habits.cli export-checks --format json --path export/checks_drink.json --name "Drink water"

Usage

All commands are run from the project root:

# Add and list
python -m habits.cli add "Drink water" --periodicity daily
python -m habits.cli list

# List only weekly habits
python -m habits.cli list-by --periodicity weekly

# Check now (marks as done for the current period)
python -m habits.cli check "Drink water"

# Show which habits are due
python -m habits.cli due

# Streaks
python -m habits.cli streak "Drink water"
python -m habits.cli streak-all

# Summary of all streaks
python -m habits.cli summary

# Manage habits
python -m habits.cli delete "Drink water"
python -m habits.cli rename "Drink water" "Hydration"

# Export data
python -m habits.cli export-habits --format json --path export/habits.json
python -m habits.cli export-checks --format csv  --path export/checks.csv
python -m habits.cli export-checks --format json --path export/checks_drink.json --name "Drink water"


All data is stored in habits.db (SQLite file in the project root).

Example Output

Habit creation and list

The output shows:

• Two new habits created (daily & weekly)
• List of all habits with periodicity and timestamps

Check-off and due

The output shows:

• One habit checked off for the current period
• Due command listing pending habits

Streak analytics

The output shows:

• Longest streak for a single habit
• Best overall streak across all habits

Design Decisions

UTC-only timestamps → avoids timezone/DST issues

Period start as key (00:00 or Monday 00:00) → ensures idempotent checks (UNIQUE(habit_id, period_start))

Pure functions for analytics (longest streak) → easy to test

Separation of concerns:

db.py → engine & session

models.py → ORM tables

repo.py → repository with business logic

cli.py → command line interface

Tests

Run the unit tests with:

pytest -q

Sample tests are included in tests/test_core.py and cover:

Period normalization (start_of_day, start_of_iso_week)

Period bounds (daily, weekly)

Longest streak calculation

Roadmap

Delete or rename habits (Check)

Summary analytics (Check)

Optional GUI (Streamlit dashboard) (In Progress)