step07_phoneBook_file.py

import os

phone_book_file_name = os.getcwd()+"/phone_book.csv"
phone_book = {}
key_value_seperator = ','

def add_phone_book_entry ():
    name = input("Enter the name of the person :")   
    if name in phone_book:     
        if not input("There is already an entry for this name overwrite [Yes/y] ? :").islower() == 'y':
            print("{} ignored".format(name))
            return

    details = input("Enter the details <number>,<address> :")
            
    phone_book[name] = details.split(',')
    print(phone_book)
    
def lookup_phone_book_entry ():
    name = input("Enter the name of the person :")
    if name in phone_book:
        print("The details of {} are {}".format(name, phone_book[name]))
    else:
        print("There is no entry for {}".format(name))    
    
def handle_input (in_val):
    if (in_val == 1):
        add_phone_book_entry()
    
    if (in_val == 2):
        lookup_phone_book_entry()
    
    if (in_val == 3):
        update_phone_book()
        quit()

def update_phone_book ():
    phone_book_file  = open(phone_book_file_name, 'a')
    phone_book_file.seek(0)
    phone_book_file.truncate()
    
    for entry in phone_book:
        val = phone_book[entry]
        phone_book_file.writelines("{name}{seperator}{number}{seperator}{address}\n".
                                   format(name=entry, seperator=key_value_seperator, 
                                          number = val[0], address = val[1] ))
        
    phone_book_file.close()

def load_phone_book ():
    with open(phone_book_file_name, 'r') as phone_book_file:
        for line in phone_book_file:
            key_value = line.split(key_value_seperator)
            phone_book[key_value[0]] = [key_value[1],key_value[2].rstrip()]
        
 
if __name__ == '__main__':
    print("Welcome to the phone book utility")
    load_phone_book()
    while True:
        print("Choose an action:")
        print("1: Add a phone book entry")
        print("2: Lookup a phone book entry")
        print("3: Exit")
        in_val = int(input(":>> "))
        handle_input(in_val)