CSV and JSON Data

import csv
from pathlib import Path

csv_path = Path.cwd() / "sample_employees.csv"

# 1. Writing sample CSV file with headers
data_rows = [
    ["emp_id", "name", "department", "salary"],
    ["101", "Alice Smith", "Engineering", "95000.00"],
    ["102", "Bob Jones", "Marketing", "72000.00"],
    ["103", "Charlie Brown", "Engineering", "105000.00"]
]

with open(csv_path, mode="w", encoding="utf-8", newline="") as f:
    writer = csv.writer(f)
    writer.writerows(data_rows)

print("=== Reading CSV using csv.DictReader (Pythonic Standard) ===")

with open(csv_path, mode="r", encoding="utf-8", newline="") as f:
    reader = csv.DictReader(f)
    for row in reader:
        # Values are automatically mapped to header column names as dictionary keys
        emp_name = row["name"]
        dept = row["department"]
        salary = float(row["salary"])
        print(f"ID #{row['emp_id']} | Name: {emp_name:<15} | Dept: {dept:<12} | Salary: ${salary:,.2f}")

=== Reading CSV using csv.DictReader (Pythonic Standard) ===
ID #101 | Name: Alice Smith     | Dept: Engineering  | Salary: $95,000.00
ID #102 | Name: Bob Jones       | Dept: Marketing    | Salary: $72,000.00
ID #103 | Name: Charlie Brown   | Dept: Engineering  | Salary: $105,000.00

import csv
from pathlib import Path

out_path = Path.cwd() / "exported_inventory.csv"

products = [
    {"product_id": "P01", "title": "Wireless Mouse", "price": 25.50, "stock": 120},
    {"product_id": "P02", "title": "Mechanical Keyboard", "price": 89.99, "stock": 45},
    {"product_id": "P03", "title": "4K Monitor", "price": 320.00, "stock": 15}
]

headers = ["product_id", "title", "price", "stock"]

with open(out_path, mode="w", encoding="utf-8", newline="") as f:
    writer = csv.DictWriter(f, fieldnames=headers)
    
    # 1. Write the header row
    writer.writeheader()
    
    # 2. Write dictionary records batch
    writer.writerows(products)

print(f"Successfully exported {len(products)} product records to: {out_path.name}")

Successfully exported 3 product records to: exported_inventory.csv

import json
from pathlib import Path

json_file_path = Path.cwd() / "system_config.json"

# Complex Python nested dictionary structure
app_config = {
    "app_name": "Apex Enterprise Engine",
    "version": "2.4.0",
    "server": {
        "host": "127.0.0.1",
        "port": 8080,
        "ssl_enabled": True
    },
    "active_modules": ["auth", "billing", "analytics"],
    "max_connections": None
}

# 1. Serializing to formatted JSON String using json.dumps()
formatted_json_str = json.dumps(app_config, indent=4)
print("=== Formatted JSON String Output ===")
print(formatted_json_str)

# 2. Writing JSON directly to Disk File using json.dump()
with open(json_file_path, mode="w", encoding="utf-8") as f:
    json.dump(app_config, f, indent=4)

print(f"\nConfig successfully saved to: {json_file_path.name}")

=== Formatted JSON String Output ===
{
    "app_name": "Apex Enterprise Engine",
    "version": "2.4.0",
    "server": {
        "host": "127.0.0.1",
        "port": 8080,
        "ssl_enabled": true
    },
    "active_modules": [
        "auth",
        "billing",
        "analytics"
    ],
    "max_connections": null
}

Config successfully saved to: system_config.json

import json
from pathlib import Path

json_file_path = Path.cwd() / "system_config.json"

# Reading and deserializing JSON file from Disk using json.load()
with open(json_file_path, mode="r", encoding="utf-8") as f:
    loaded_config = json.load(f)

print("=== Deserialized Python Dictionary Object ===")
print(f"Loaded Object Type : {type(loaded_config)}")
print(f"App Title          : {loaded_config['app_name']}")
print(f"Host Port Target   : {loaded_config['server']['host']}:{loaded_config['server']['port']}")
print(f"First Active Module: {loaded_config['active_modules'][0]}")

=== Deserialized Python Dictionary Object ===
Loaded Object Type : 
App Title          : Apex Enterprise Engine
Host Port Target   : 127.0.0.1:8080
First Active Module: auth

import csv
import json
from pathlib import Path

def process_data_payload(command_payload: list):
    """
    Routes and transforms CSV/JSON data using Structural Pattern Matching.
    Demonstrates handling structured file formats dynamically.
    """
    match command_payload:
        case ["EXPORT_JSON", filename, dict_data] if isinstance(dict_data, dict):
            target_path = Path.cwd() / filename
            with open(target_path, mode="w", encoding="utf-8") as f:
                json.dump(dict_data, f, indent=2)
            return f"SUCCESS: Exported JSON dictionary to '{filename}'."
            
        case ["EXPORT_CSV", filename, [head_row, *data_rows]] if len(data_rows) > 0:
            target_path = Path.cwd() / filename
            with open(target_path, mode="w", encoding="utf-8", newline="") as f:
                writer = csv.writer(f)
                writer.writerow(head_row)
                writer.writerows(data_rows)
            return f"SUCCESS: Exported CSV table with {len(data_rows)} rows to '{filename}'."
            
        case ["PARSE_JSON_KEY", filename, target_key]:
            target_path = Path.cwd() / filename
            if not target_path.exists():
                return f"ERROR: File '{filename}' does not exist!"
            with open(target_path, mode="r", encoding="utf-8") as f:
                payload = json.load(f)
            extracted = payload.get(target_key, "KEY_NOT_FOUND")
            return f"EXTRACTED [{target_key}]: {extracted}"
            
        case _:
            return "ERROR: Unrecognized structured payload command schema."

# Testing the dispatcher
sample_user = {"id": 881, "username": "alice_dev", "status": "ACTIVE"}
table_data = [["ID", "Role"], [101, "Admin"], [102, "Editor"]]

print(process_data_payload(["EXPORT_JSON", "user_881.json", sample_user]))
print(process_data_payload(["EXPORT_CSV", "roles.csv", table_data]))
print(process_data_payload(["PARSE_JSON_KEY", "user_881.json", "username"]))

SUCCESS: Exported JSON dictionary to 'user_881.json'.
SUCCESS: Exported CSV table with 2 rows to 'roles.csv'.
EXTRACTED [username]: alice_dev