- Create a Many-to-many relationship using an intermediary class.
- Write aggregate methods.
- Class: a bundle of data and functionality. Can be copied and modified to accomplish a wide variety of programming tasks.
- Object: the more common name for an instance. The two can usually be used interchangeably.
- Object-Oriented Programming: programming that is oriented around data (made mobile and changeable in objects) rather than functionality. Python is an object-oriented programming language.
- Function: a series of steps that create, transform, and move data.
- Method: a function that is defined inside of a class.
In this lab we will implement a one-to-many relationship between a Author
, Book
, and Contract
.
This is a test-driven lab. Run pipenv install
to create your virtual
environment and pipenv shell
to enter the virtual environment. Then run
pytest -x
to run your tests. Use these instructions and pytest
's error
messages to complete your work in the lib/
folder.
Create a Book class that has the following attributes: title
(string)
Create an Author class that has the following attributes: name
(string)
Create a Contract class that has the following properties:
author
(Author object), book
(Book object), date
(string), and royalties
(int).
All classes should also keep track of all
members using a class variable.
- The author property should be an instance of the Author class, while the book
property should be an instance of the Book class. The date property should be a
string that represents the date when the contract was signed, while the
royalties property should be a number that represents the percentage of
royalties that the author will receive for the book.
- All setters should
raise Exception
upon failure.
- All setters should
The Author
class should have the following methods:
contracts(self)
: This method should return a list of related contracts.books(self)
: This method should return a list of related books using theContract
class as an intermediary.sign_contract(book, date, royalties)
: This method should create and return a newContract
object between the author and the specified book with the specified date and royaltiestotal_royalties()
: This method should return the total amount of royalties that the author has earned from all of their contracts.
The Contract
class should have the following methods:
- A class method
contracts_by_date
(cls, date): This method should return all contracts that have the same date as the date passed into the method.