Project: A CRUD List Manager

By the end of this lesson you can:

• Build a menu loop that keeps running until the user chooses to quit.
• Implement create, read, update and delete over one list of records.
• Validate a menu choice and a record number so nothing crashes.

You have already written all four operations in this section. Match each to the tool you used.

A stall that stays open. Show the menu, take one order, deal with it, show the menu again — until someone says "that is all".

tasks = []

while True:
    print()
    print("1 Add   2 View   3 Quit")
    choice = input("Choose: ").strip()

    if choice == "1":
        tasks.append(input("Task: ").strip())
    elif choice == "2":
        print(tasks)
    elif choice == "3":
        print("Bye!")
        break
    else:
        print("Please choose 1, 2 or 3.")

Three parts, and every menu program has them:

• while True — loop forever, on purpose.
• break — the only way out, reached by one deliberate choice.
• A final else — so a typo says something useful instead of silently doing nothing.

Records, not parallel lists

Lesson 5 showed why: sort two parallel lists separately and they stop matching. Keep each record as one small list.

# Each task is [description, done]
tasks = [
    ["Finish homework", False],
    ["Tidy room", True],
]

for description, done in tasks:
    mark = "x" if done else " "
    print(f"[{mark}] {description}")

Output

[ ] Finish homework
[x] Tidy room

Asking for a record number safely

The user sees 1, 2, 3; the list uses 0, 1, 2. Both the conversion and the range need checking.

def ask_index(prompt, items):
    """Ask for a record number, return its index, or -1 if unusable."""
    if not items:
        print("Nothing in the list yet.")
        return -1

    raw = input(prompt).strip()
    if not raw.isdigit():
        print("Please type a number.")
        return -1

    number = int(raw)
    if number < 1 or number > len(items):
        print(f"Choose between 1 and {len(items)}.")
        return -1

    return number - 1

Three guards in nine lines: empty list, not a number, out of range. Every one of them is a crash you have already met in this section.

Type it in four goes, running after each. Do not paste the whole thing.

Step 1 — the data and the view

# manager.py - add, view, edit and delete a list of tasks

tasks = [
    ["Finish Sejarah homework", False],
    ["Practise piano", True],
    ["Buy gift for Ella", False],
]


def show_all():
    """Read - print every task with its number."""
    print()
    if not tasks:
        print("  (nothing yet)")
        return

    print(f"  {'#':<4}{'Done':<6}Task")
    for i in range(len(tasks)):
        description, done = tasks[i]
        mark = "yes" if done else "no"
        print(f"  {i + 1:<4}{mark:<6}{description}")

    outstanding = 0
    for description, done in tasks:
        if not done:
            outstanding = outstanding + 1
    print(f"  {len(tasks)} tasks, {outstanding} still to do")

Step 2 — the safe index helper

def ask_index(prompt):
    """Ask for a task number, return its index, or -1 if unusable."""
    if not tasks:
        print("Nothing in the list yet.")
        return -1

    raw = input(prompt).strip()
    if not raw.isdigit():
        print("Please type a number.")
        return -1

    number = int(raw)
    if number < 1 or number > len(tasks):
        print(f"Choose between 1 and {len(tasks)}.")
        return -1

    return number - 1

Step 3 — create, update, delete

def add_task():
    """Create - append a new record."""
    description = input("New task: ").strip()
    if description == "":
        print("A task needs a description.")
        return
    tasks.append([description, False])
    print("Added:", description)


def edit_task():
    """Update - change one field of one record."""
    i = ask_index("Edit which number? ")
    if i == -1:
        return

    print("Current:", tasks[i][0])
    new_text = input("New wording (Enter to keep): ").strip()
    if new_text != "":
        tasks[i][0] = new_text

    tasks[i][1] = not tasks[i][1]
    print("Updated:", tasks[i][0], "- done:", tasks[i][1])


def delete_task():
    """Delete - pop, so the record can be reported."""
    i = ask_index("Delete which number? ")
    if i == -1:
        return

    removed = tasks.pop(i)
    print("Deleted:", removed[0])

Step 4 — the menu loop

while True:
    print()
    print("1 View   2 Add   3 Edit   4 Delete   5 Sort   6 Quit")
    choice = input("Choose: ").strip()

    if choice == "1":
        show_all()
    elif choice == "2":
        add_task()
    elif choice == "3":
        edit_task()
    elif choice == "4":
        delete_task()
    elif choice == "5":
        tasks.sort(key=lambda task: task[0].lower())
        print("Sorted by description.")
        show_all()
    elif choice == "6":
        print("Goodbye!")
        break
    else:
        print("Please choose 1 to 6.")

A short session

1 View   2 Add   3 Edit   4 Delete   5 Sort   6 Quit
Choose: 1

  #   Done  Task
  1   no    Finish Sejarah homework
  2   yes   Practise piano
  3   no    Buy gift for Ella
  3 tasks, 2 still to do

Choose: 2
New task: Revise for Maths test
Added: Revise for Maths test

Choose: 3
Edit which number? 1
Current: Finish Sejarah homework
New wording (Enter to keep):
Updated: Finish Sejarah homework - done: True

Choose: 4
Delete which number? 9
Choose between 1 and 4.

Choose: 6
Goodbye!

The out-of-range delete is the important line: it refused politely and the loop carried on. Nothing was lost.

Six lessons, and this project used all of them. Lists are numbered from 0 and sliced up to but not including the end; they are mutable, so they change in place and a copy needs [:]; append and pop grow and shrink them; in, index, count and the built-ins answer questions without loops; and sorted with key= orders them however you like. CRUD is those tools behind a menu.

Where next. Section 3 · Dictionaries replaces task[0] and task[1] with task["description"], so records stop depending on remembering which position means what. Section 4 · File Handling makes the list survive closing the program.