Borrowing System
Part of the Object Oriented Programming section of Coddy's Python journey — lesson 57 of 64.
Challenge
MediumIn this challenge, you'll add borrowing functionality to the library management system.
Edit library.py and implement the borrow_book method, following the TODO comments.
The other files are provided for you and are locked:
book.py— theBookclass you built in the previous challengeuser.py— theUserclass, holdinguser_id,nameandbooks_borroweddriver.py— runs the test scenarios against your implementation
borrow_book(book_isbn, user_id) must return exactly one of: "Book not found", "User not found", "Book is not available", or "Book borrowed successfully".
Try it yourself
from book import Book
from user import User
from library import Library
# Comprehensive test case handler
test_case = input()
# Basic functionality tests
if test_case == "borrow_success":
library = Library("Community Library")
# Add books and users
book = Book("The Great Gatsby", "F. Scott Fitzgerald", "123456")
library.add_book(book)
user = User("U001", "Alice")
library.add_user(user)
# Borrow book
result = library.borrow_book("123456", "U001")
print(result)
print(f"Book available: {book.available}")
print(f"Books borrowed by user: {len(user.books_borrowed)}")
elif test_case == "book_not_found":
library = Library("Community Library")
user = User("U001", "Alice")
library.add_user(user)
result = library.borrow_book("nonexistent", "U001")
print(result)
elif test_case == "user_not_found":
library = Library("Community Library")
book = Book("The Great Gatsby", "F. Scott Fitzgerald", "123456")
library.add_book(book)
result = library.borrow_book("123456", "nonexistent")
print(result)
elif test_case == "book_not_available":
library = Library("Community Library")
# Add books and users
book = Book("The Great Gatsby", "F. Scott Fitzgerald", "123456")
book.available = False # Book is already borrowed
library.add_book(book)
user = User("U001", "Alice")
library.add_user(user)
# Try to borrow unavailable book
result = library.borrow_book("123456", "U001")
print(result)
# Edge cases and additional tests
elif test_case == "multiple_books":
library = Library("Community Library")
user = User("U001", "Alice")
library.add_user(user)
# Create multiple books
books = [
Book("Book 1", "Author 1", "111"),
Book("Book 2", "Author 2", "222"),
Book("Book 3", "Author 3", "333")
]
for book in books:
library.add_book(book)
# Borrow multiple books
results = []
for book in books:
results.append(library.borrow_book(book.isbn, "U001"))
for result in results:
print(result)
print(f"Total books borrowed: {len(user.books_borrowed)}")
elif test_case == "multiple_users":
library = Library("Community Library")
book = Book("Popular Book", "Famous Author", "999")
library.add_book(book)
# Create multiple users
users = [
User("U001", "Alice"),
User("U002", "Bob"),
User("U003", "Charlie")
]
for user in users:
library.add_user(user)
# Try to borrow the same book with different users
result1 = library.borrow_book("999", "U001")
result2 = library.borrow_book("999", "U002") # Should fail
print(result1)
print(result2)
print(f"Book's borrower: {book.borrower.name}")
elif test_case == "return_book":
library = Library("Community Library")
book = Book("The Great Gatsby", "F. Scott Fitzgerald", "123456")
library.add_book(book)
user = User("U001", "Alice")
library.add_user(user)
# Borrow the book
borrow_result = library.borrow_book("123456", "U001")
print(borrow_result)
# Verify book status
print(f"Book available: {book.available}")
print(f"Book borrower: {book.borrower.name}")
print(f"User's borrowed books: {len(user.books_borrowed)}")
print(f"First borrowed book title: {user.books_borrowed[0].title}")
elif test_case == "empty_library":
library = Library("Empty Library")
result = library.borrow_book("any_isbn", "any_user_id")
print(result)
elif test_case == "borrower_reference":
library = Library("Community Library")
book = Book("The Great Gatsby", "F. Scott Fitzgerald", "123456")
library.add_book(book)
user = User("U001", "Alice")
library.add_user(user)
# Borrow the book
library.borrow_book("123456", "U001")
# Verify references
print(f"Book's borrower name: {book.borrower.name}")
print(f"First book in user's borrowed list: {user.books_borrowed[0].title}")All lessons in Object Oriented Programming
1Fundamentals of OOP
External FilesIntroduction to OOPClasses vs ObjectsThe self ParameterMethodsAttributesConstructor Method (__init__)Recap - Simple Calculator4Inheritance
Basic InheritanceThe super() FunctionMethod OverridingMultiple InheritanceMethod Resolution OrderRecap - Employee Hierarchy7Special Methods
Magic Methods IntroductionOperator OverloadingContainer Magic MethodsRecap - Custom List10Design Patterns Part 1
Intro to design patternSingleton PatternFactory PatternObserver PatternStrategy Pattern2Decorators
Introduction to DecoratorsProperty DecoratorStatic Method DecoratorClass Method Decorator5Polymorphism
Method Overriding RevisitedDuck TypingAbstract Classes and MethodsInterface DesignRecap - Shape Calculator8Advanced OOP Concepts
Composition vs InheritanceMixinsStatic and Class MethodsClass DecoratorsContext Managers3Class Properties
Instance vs Class VariablesProperty DecoratorsPrivate AttributesRecap - Bank Account Manager6Encapsulation
Public, Protected, Private MemAccess ModifiersInformation HidingProperty Decorators AdvancedRecap - Student Records System12Project: Library Management
Project OverviewBook and User ClassesBorrowing SystemSearch FunctionalityAdmin InterfaceTesting and Integration