CRUD Operations - Coders Management

Build a complete Create, Read, Update, Delete (CRUD) system to manage a list of coders with their information

Overview

This exercise implements a full CRUD (Create, Read, Update, Delete) system for managing coder records. You’ll work with lists of dictionaries, create a menu-driven interface, and perform all four fundamental database operations.

Difficulty Level: Intermediate

Concepts Covered: Lists, dictionaries, while loops, menu systems, data manipulation, indexing

What You’ll Learn

1. Working with Complex Data Structures

   Manage lists containing dictionaries to represent structured data

2. CRUD Operations

   Implement Create, Read, Update, and Delete functionality

3. Menu-Driven Programs

   Build an interactive menu system using while loops

4. Data Indexing

   Use indices to access and modify specific records in a list

Complete Code

Here’s the full CRUD system implementation:

coders=[
    {
        "nombre":"Javier",
        "edad":25,
        "riwipoints":4
    },
    {
        "nombre":"lucas",
        "edad":18,
        "riwipoints":8
    },
    {
        "nombre":"pablo",
        "edad":30,
        "riwipoints":5
    },
    {
        "nombre":"judas",
        "edad":19,
        "riwipoints":0
    },
    {
        "nombre":"mateo uno",
        "edad":36,
        "riwipoints":9
    }
]

while True:
    print("""
    MENU
    (1) registrar un nuevo coder

    (2) actualizar coder

    (3) eliminar coder

    (4) listar coders

    (5) cerrar programa
    """)

    opcionMenu=input("INGRESA LA OPCION=>")
    if opcionMenu=="1":
        nombre=input("ingresa el nombre del coder=>")
        edad=int(input("ingresa la edad del coder=>"))
        riwipoints=int(input("ingresa los riwipoints del coder=>"))

        nuevoCoder={
            "nombre":nombre,
            "edad":edad,
            "riwipoints":riwipoints
        }

        coders.append(nuevoCoder)
    elif opcionMenu=="2":
        indice=0
        for coder in coders:
            #mostrar informacion de coders
            print(f"""
                id=[{indice}]
                Nombre={coder["nombre"]}
                Edad={coder["edad"]}
                Riwipoints={coder["riwipoints"]}
                """)
            indice+=1

        #pedimos los nuevos datos   
        coderParaActualizar=int(input("ingresa el id del coder que quieres actualizar=>"))
        nuevoNombre=input("ingresa el nuevo nombre del coder=>")
        nuevaEdad=int(input("ingresa la nueva edad del coder=>"))
        nuevosRiwipoints=int(input("ingresa los nuevos riwipoints del coder=>"))

        #actualizar los nuevos datos
        coders[coderParaActualizar]["nombre"]=nuevoNombre
        coders[coderParaActualizar]["edad"]=nuevaEdad
        coders[coderParaActualizar]["riwipoints"]=nuevosRiwipoints
    elif opcionMenu=="3":
        indice=0
        for coder in coders:
            print(f"id=[{indice}] - {coder["nombre"]}")
            indice+=1

        coderAeliminar=int(input("ingrese el ID del coder que quiere eliminar"))
        del coders[coderAeliminar]
    elif opcionMenu=="4":
        print("lista de coders")
        for coder in coders:
            print(f"""
                NOMBRE CODER= {coder["nombre"]}
                EDAD= {coder["edad"]}
                RIWIPOINTS= {coder["riwipoints"]}
                """)
    elif opcionMenu=="5":
        print("aca vamos a cerrar")
        break
    else:
       print("ingresastes una opcion invalida")

Code Breakdown

Section 1: Initial Data Structure

coders=[
    {
        "nombre":"Javier",
        "edad":25,
        "riwipoints":4
    },
    # ... more coders
]

Data Structure: A list of dictionaries. Each dictionary represents a coder with three properties: nombre (name), edad (age), and riwipoints (points). This structure allows easy access to individual properties while keeping related data together.

Section 2: Main Menu Loop

while True:
    print("""
    MENU
    (1) registrar un nuevo coder
    (2) actualizar coder
    (3) eliminar coder
    (4) listar coders
    (5) cerrar programa
    """)
    opcionMenu=input("INGRESA LA OPCION=>")

Why while True?

The while True loop creates an infinite loop that keeps the program running until the user explicitly chooses to exit (option 5). This pattern is common in menu-driven applications where you want continuous interaction until the user decides to quit.

Section 3: CREATE Operation

if opcionMenu=="1":
    nombre=input("ingresa el nombre del coder=>")
    edad=int(input("ingresa la edad del coder=>"))
    riwipoints=int(input("ingresa los riwipoints del coder=>"))

    nuevoCoder={
        "nombre":nombre,
        "edad":edad,
        "riwipoints":riwipoints
    }

    coders.append(nuevoCoder)

1. Collect Input

   Gather all necessary information from the user

2. Create Dictionary

   Build a new dictionary object with the collected data

3. Add to List

   Use .append() to add the new coder to the end of the list

Section 4: UPDATE Operation

elif opcionMenu=="2":
    indice=0
    for coder in coders:
        print(f"""
            id=[{indice}]
            Nombre={coder["nombre"]}
            Edad={coder["edad"]}
            Riwipoints={coder["riwipoints"]}
            """)
        indice+=1

    coderParaActualizar=int(input("ingresa el id del coder que quieres actualizar=>"))
    nuevoNombre=input("ingresa el nuevo nombre del coder=>")
    nuevaEdad=int(input("ingresa la nueva edad del coder=>"))
    nuevosRiwipoints=int(input("ingresa los nuevos riwipoints del coder=>"))

    coders[coderParaActualizar]["nombre"]=nuevoNombre
    coders[coderParaActualizar]["edad"]=nuevaEdad
    coders[coderParaActualizar]["riwipoints"]=nuevosRiwipoints

Index Tracking: The indice variable manually tracks the position of each coder. This allows users to reference coders by a numeric ID. The update uses bracket notation to modify dictionary values directly.

Section 5: DELETE Operation

elif opcionMenu=="3":
    indice=0
    for coder in coders:
        print(f"id=[{indice}] - {coder["nombre"]}")
        indice+=1

    coderAeliminar=int(input("ingrese el ID del coder que quiere eliminar"))
    del coders[coderAeliminar]

The del statement removes an element from the list at the specified index. After deletion, all subsequent elements shift down one position.

Section 6: READ Operation

elif opcionMenu=="4":
    print("lista de coders")
    for coder in coders:
        print(f"""
            NOMBRE CODER= {coder["nombre"]}
            EDAD= {coder["edad"]}
            RIWIPOINTS= {coder["riwipoints"]}
            """)

This simple loop iterates through all coders and displays their information in a formatted way.

Section 7: Exit and Error Handling

elif opcionMenu=="5":
    print("aca vamos a cerrar")
    break
else:
   print("ingresastes una opcion invalida")

The break statement exits the while loop, ending the program. The else clause catches any invalid menu options.

How to Run

1. Save the File

   Save the code in a file named crud_coders.py

2. Run the Program

   Execute from your terminal:

   python crud_coders.py
   
3. Interact with the Menu

   • Choose option 1 to add a new coder
   • Choose option 2 to update an existing coder
   • Choose option 3 to delete a coder
   • Choose option 4 to view all coders
   • Choose option 5 to exit

Example Usage

MENU
(1) registrar un nuevo coder
(2) actualizar coder
(3) eliminar coder
(4) listar coders
(5) cerrar programa

INGRESA LA OPCION=>1
ingresa el nombre del coder=>Maria
ingresa la edad del coder=>28
ingresa los riwipoints del coder=>7

MENU
(1) registrar un nuevo coder
(2) actualizar coder
(3) eliminar coder
(4) listar coders
(5) cerrar programa

INGRESA LA OPCION=>4
lista de coders

NOMBRE CODER= Javier
EDAD= 25
RIWIPOINTS= 4

NOMBRE CODER= lucas
EDAD= 18
RIWIPOINTS= 8

... [more coders]

NOMBRE CODER= Maria
EDAD= 28
RIWIPOINTS= 7

Enhancement Ideas

Ways to Improve This Program

1. Data Persistence: Save data to a JSON file so it persists between program runs
2. Search Functionality: Add a search feature to find coders by name or other criteria
3. Input Validation: Prevent negative ages or invalid riwipoints values
4. Sorting: Add options to sort coders by name, age, or points
5. Confirmation Dialogs: Ask for confirmation before deleting records
6. Unique IDs: Use UUID or auto-increment IDs instead of list indices
7. Error Handling: Use try-except blocks to handle IndexError when accessing invalid indices

Common Issues and Solutions

IndexError: list index out of range

Problem: User enters an ID that doesn’t exist.

Solution: Validate the index before accessing:

if 0 <= coderParaActualizar < len(coders):
    # perform update
else:
    print("ID invalido")

ValueError: invalid literal for int()

Problem: User enters non-numeric input for age or riwipoints.

Solution: Add try-except blocks:

try:
    edad = int(input("ingresa la edad del coder=>"))
except ValueError:
    print("Por favor ingresa un número válido")

Key Takeaways

• Lists of dictionaries are excellent for managing collections of structured data
• CRUD operations form the foundation of most data management systems
• Menu-driven programs use while loops and conditional statements for user interaction
• Index tracking allows users to reference specific records by ID
• The del statement removes elements from lists
• Dictionary keys can be accessed and modified using bracket notation
• Breaking down complex operations into clear steps improves code readability