This demo showcases a useful technique for serializing classes to JSON using the vars() method.
Definitions
Some terms to help you navigate the post
vars()
A method that takes a class instance and returns a dict of the instance attributes
JSON
JSON is a file format used to store data in key-value pairs. More information can be found here
Usage
You can run the demo code and actually run it by running python vars.py or python3 vars.py
Real World Applications
This method is useful if you are writing a simple application that needs to serve class instances via a REST endpoint, or are looking for easy serialization to a cross platform format.
Files
example_class_demo.py
"""
This file is here to create a sample class to show off the vars() method
"""
class user:
def __init__(self, name, age, birthday, country, address):
"""
A generic user class to store information about people.
Parameters
----------
name : string
User instances' name
age : int
User instances' age
birthday : string
User instances' birthday
Country : string
User instances' current country location
address : string
User instances' address
"""
self.name = name
self.age = age
self.birthday = birthday
self.country = country
self.address = address
vars_demo.py
"""A demo of the vars function, specifically it's usage to expedite JSON serialization
vars() is a function that takes an object instance as an argument and returns a dict
of the instance attributes.
SEE: vars documentation https://docs.python.org/3/library/functions.html#vars
"""
import json # Used to serialize data to a JSON file SEE: https://docs.python.org/3/library/json.html
from example_class import user # Dummy class to instantiate, and serialize
example_user = user("John Doe", 21, "22-10-1995", "Australia", "123 Main Street") # Instantiate an example to use later
print("User class vars output: ")
# outputs: {'name': 'John Doe', 'age': 21, 'birthday': '22-10-1995', 'country': 'Australia', 'address': '123 Main Street'}
print(vars(example_user))
# You can use vars with json.dump to serialize a class instance to a json file
json.dump(vars(example_user), open("user.json", "w"))