Exercise 09-38:
Modify the previous program to read the same file, allowing you to add more data. If the same name is entered twice, update the data using the new entry.
Tip: You may have to use a list of dictionaries to hold multiple entries.
Answer:
##############################################################################
# Python From Scratch
# Author: Nilo Ney Coutinho Menezes
# Editora Novatec (c) 2010-2025 - LogiKraft 2025
# Site: https://pythonfromscratch.com
# ISBN: 978-85-7522-949-1 (Paperback), 978-85-7522-950-7 (hardcover), 978-85-7522-951-4 (ebook)
#
# File: chapter 09/exercise-09-38.py.py
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import json
import os
def read_grades():
grades = []
for i in range(4):
grade = float(input(f"Enter the {i+1}th grade: "))
grades.append(grade)
return grades
def load_data():
# If the file doesn't exist, returns an empty list
if not os.path.exists("student_grades.json"):
return []
try:
with open("student_grades.json", "r") as file:
return json.load(file)
except json.JSONDecodeError:
return []
# Reading existing data
students = load_data()
# Reading new data
name = input("Enter student name: ")
grades = read_grades()
# Creating dictionary with new data
new_student = {"name": name, "grades": grades}
# Checks if student already exists and updates, or adds new student
student_exists = False
for i, student in enumerate(students):
if student["name"] == name:
students[i] = new_student
student_exists = True
break
if not student_exists:
students.append(new_student)
# Saving all data to JSON file
with open("student_grades.json", "w") as file:
json.dump(students, file, indent=4)
print("Student data successfully saved to 'student_grades.json' file.")