Week 10 — Basic Capstone: CLI To-Do App

Combine everything from weeks 1–9 into a full command-line to-do application with add, list, complete, and delete commands. Optionally persist tasks to a JSON file.

capstoneprojectCLIJSONintegration

Duration

⏱ 3 hours

Level

📊 Beginner

Prerequisite

🎯 Weeks 1–9

OUTCOME

A working CLI to-do app you can run from the terminal

What you'll learn

1Integrate lists, dicts, functions, and loops in one project
2Handle user input robustly with error messages
3Save and load tasks from a JSON file
4Structure code into well-named functions
5Practice the full development loop: plan → code → test

1. Project Specification

Commands: add <title>, list, done <id>, delete <id>, quit
Each task: id (auto-increment), title, done (bool)
Persist tasks in tasks.json on disk
Show task count and completion stats on list

2. Architecture

load_tasks() / save_tasks() — JSON file I/O
add_task(tasks, title) — append new task dict
list_tasks(tasks) — print numbered table
mark_done(tasks, task_id) — find by id and set done=True
delete_task(tasks, task_id) — filter out by id
main() — REPL loop with command dispatch

3. Sample Session

text

Todo App — type 'help' for commands
> add Buy groceries
  [1] added.
> add Write report
  [2] added.
> list
  ID  Status  Title
  1   [ ]     Buy groceries
  2   [ ]     Write report
> done 1
  [1] marked as done.
> list
  ID  Status  Title
  1   [x]     Buy groceries
  2   [ ]     Write report
  Done: 1/2
> quit
  Bye!

4. Extension Challenges

Add a priority field (high/medium/low) and sort by priority on list
Add a due date field and highlight overdue tasks in red (colorama)
Add search <keyword> command to filter tasks

💻 Examples

Run these examples and check the output yourself.

todo.py— Complete to-do app implementation

CODE

import json, os

FILE = "tasks.json"

def load_tasks():
    if os.path.exists(FILE):
        with open(FILE) as f:
            return json.load(f)
    return []

def save_tasks(tasks):
    with open(FILE, "w") as f:
        json.dump(tasks, f, indent=2)

def add_task(tasks, title):
    task_id = max((t["id"] for t in tasks), default=0) + 1
    tasks.append({"id": task_id, "title": title, "done": False})
    print(f"  [{task_id}] added.")

def list_tasks(tasks):
    if not tasks:
        print("  No tasks.")
        return
    print(f"  {'ID':<4} {'Status':<8} Title")
    for t in tasks:
        status = "[x]" if t["done"] else "[ ]"
        print(f"  {t['id']:<4} {status:<8} {t['title']}")
    done = sum(1 for t in tasks if t["done"])
    print(f"  Done: {done}/{len(tasks)}")

def mark_done(tasks, task_id):
    for t in tasks:
        if t["id"] == task_id:
            t["done"] = True
            print(f"  [{task_id}] marked as done.")
            return
    print(f"  Task {task_id} not found.")

def delete_task(tasks, task_id):
    orig = len(tasks)
    tasks[:] = [t for t in tasks if t["id"] != task_id]
    if len(tasks) < orig:
        print(f"  [{task_id}] deleted.")
    else:
        print(f"  Task {task_id} not found.")

def main():
    tasks = load_tasks()
    print("Todo App — type 'help' for commands")
    while True:
        line = input("> ").strip()
        if not line:
            continue
        parts = line.split(maxsplit=1)
        cmd = parts[0].lower()
        arg = parts[1] if len(parts) > 1 else ""
        if cmd == "add":
            if arg:
                add_task(tasks, arg)
                save_tasks(tasks)
            else:
                print("  Usage: add <title>")
        elif cmd == "list":
            list_tasks(tasks)
        elif cmd == "done":
            try:
                mark_done(tasks, int(arg))
                save_tasks(tasks)
            except ValueError:
                print("  Usage: done <id>")
        elif cmd == "delete":
            try:
                delete_task(tasks, int(arg))
                save_tasks(tasks)
            except ValueError:
                print("  Usage: delete <id>")
        elif cmd in ("quit", "exit"):
            print("  Bye!")
            break
        elif cmd == "help":
            print("  Commands: add <title>, list, done <id>, delete <id>, quit")
        else:
            print(f"  Unknown command: {cmd}")

if __name__ == "__main__":
    main()

📝 Exercises

Try them yourself first, then open the solution to compare.

Exercise 1

Implement the base app

Goal: Implement the to-do app as described with add, list, done, delete, and quit.

Requirements

All 5 commands work correctly
Tasks persist across runs (JSON file)
Invalid input shows helpful error messages

Grading

· add/list work — 30%
· done/delete work — 30%
· JSON persistence — 30%
· Error handling — 10%

Exercise 2

Add priority support

Goal: Extend the app with a priority field (high/medium/low).

Requirements

add command accepts optional priority: add <title> [--priority high]
list sorts by priority: high → medium → low
Priority shown in list output

Example code / lecture materials

All lecture materials and example code are openly available on GitHub.

View on GitHub ↗