Object Relations in Python

Nili (Scharf) Ambinder

2 min read

·

Mar 8, 2025

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Understanding object relations in data-based applications is essential. Object relations underscore how objects interact with each other. The most fundamental relationships are the one-to-many relationship and the many-to-many relationship. Object relations are achieved in Python via classes and object-oriented programming. Object Relational Mapping (ORM) is helpful in order ot use Python objects to interact with databases.

In Python, object relations are demonstrated through classes. In a one-to-many relationship, for example, a single Author who writes many Books, the one-to-many relationship appears as follows:

class Author:
  def __init__(self, name):
    self.name = name
    self.books = [] # initializing a list of books, this is the one-to-many relationship
  
  def write_book(self, title):
    book = Book(self, title)
    self.books.append(book)
    return book

class Book:
  def __init__(self, author, title):
    self.author = author
    self.title = title 

# Example
author = Author("Jack")
author.write_book("Object Relations")
print("author.book[0].title") # Output: Object Relations 

An example of a many-to-many relationship would be many authors who write many magazines:

class Magazine:
    def __init__(self, name):
        self.name = name
        self.articles = []

    def add_article(self, article):
        self.articles.append(article)

class Article:
    def __init__(self, author, magazine, title):
        self.author = author
        self.magazine = magazine
        self.title = title
        magazine.add_article(self)

# Example 
author = Author("Jack")
magazine = Magazine("Techy")
author.write_article("Object Relations Explained")
Article(author, magazine, "Object Relations Explained")

Using ORM helps us use Python objects in order to interact with databases in a very clear way.

Object relations are crucial to creating efficient applications. Python classes are the building blocks to better understand ORM’s and, in turn, improved interactions with databases in a productive and maintainable way.