Introduction

Knowing syntax is one thing. Building a real project is another. In this post, we’ll cover:

• How to call APIs and handle JSON responses
• Structuring Python projects across multiple files
• The Contact Book mini-project that ties everything together

By the end, you’ll have a blueprint for any Python application.

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API Integration: Fetching Live Data

APIs (Application Programming Interfaces) allow your code to talk to external services. Most modern APIs return JSON.

Using the requests library

python

import requests

response = requests.get("https://api.github.com/users/octocat")
if response.status_code == 200:
    data = response.json()  # Parse JSON
    print(data["name"])
else:
    print("API call failed")

Common API Workflow

1. Send HTTP request (GET, POST, etc.)
2. Check status code (200 = OK, 404 = Not Found, 500 = Server Error)
3. Parse JSON response
4. Handle errors gracefully

Example: Weather API

python

def get_weather(city):
    url = f"https://api.openweathermap.org/data/2.5/weather?q={city}&appid=YOUR_KEY"
    try:
        response = requests.get(url, timeout=5)
        response.raise_for_status()  # Raises exception for 4xx/5xx
        return response.json()
    except requests.exceptions.RequestException as e:
        return {"error": str(e)}

Always set a timeout and use raise_for_status().

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Multi-File Project Structure

A professional Python project is never one huge file. You split by responsibility.

Example Structure:

text

contact_book/
│
├── main.py          # Entry point
├── contact_manager.py   # Business logic
├── file_handler.py      # JSON read/write
├── utils.py             # Helper functions
└── data/
    └── contacts.json    # Storage

How Imports Work

python

# In main.py
from contact_manager import add_contact
from file_handler import load_contacts

Use absolute imports for clarity. Avoid from module import *.

if __name__ == "__main__" Explained

This ensures code runs only when the script is executed directly, not when imported.

python

# main.py
def main():
    print("Contact Book Started")

if __name__ == "__main__":
    main()

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Contact Book Mini Project: Tying It All Together

This project uses:

• OOP (Contact class)
• File handling (JSON storage)
• Exception handling
• Multi-file structure

Contact Class (OOP)

python

# models.py
class Contact:
    def __init__(self, name, phone, email):
        self.name = name
        self.phone = phone
        self.email = email

    def to_dict(self):
        return {"name": self.name, "phone": self.phone, "email": self.email}

JSON Storage Handler

python

# storage.py
import json

def save_contacts(contacts):
    with open("data/contacts.json", "w") as file:
        json.dump([c.to_dict() for c in contacts], file, indent=4)

def load_contacts():
    try:
        with open("data/contacts.json", "r") as file:
            data = json.load(file)
            return [Contact(**item) for item in data]
    except FileNotFoundError:
        return []

Main Logic

python

# main.py
def add_contact(contacts):
    name = input("Name: ")
    phone = input("Phone: ")
    email = input("Email: ")
    contacts.append(Contact(name, phone, email))
    save_contacts(contacts)

This is production-style code: modular, reusable, and error-resistant.

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Skills You Build

• Logic building: Breaking features into small functions
• Debugging: Using print statements and try-except
• Real-world readiness: Code that other developers can understand

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