Python - Convert Class Object to JSON

Python - Convert Class Object to JSON

To convert a Python Class Object to JSON String, or save the parameters of the class object to a JSON String, use the json.dumps() method.

In this tutorial, we will learn how to construct a JSON string from a Python class object using json.dumps() and some common use cases.

Syntax of json.dumps()

Following is the syntax of the json.dumps() function.

jsonStr = json.dumps(myobject.__dict__)

where

  • json is the module.
  • dumps is the method that converts the Python object to a JSON string. It returns a JSON string.
  • myobject is the Python Class object, and myobject.__dict__ gets the dictionary version of object parameters.

Examples

1. Convert Class Object to JSON String

In this example, we define a simple Python class, Laptop, create an object of this class, and then convert its properties to a JSON string.

Python Program

import json

class Laptop:
	name = 'My Laptop'
	processor = 'Intel Core'
	
#create object
laptop1 = Laptop()
laptop1.name = 'Dell Alienware'
laptop1.processor = 'Intel Core i7'

#convert to JSON string
jsonStr = json.dumps(laptop1.__dict__)

#print JSON string
print(jsonStr)

Explanation:

  1. The class Laptop has two attributes: name and processor.
  2. We create an object of the Laptop class called laptop1, and assign it specific values for the attributes.
  3. By using json.dumps(laptop1.__dict__), we convert the object's attributes into a dictionary, which is then converted to a JSON string.
  4. The resulting output is a JSON string representation of the object's attributes.

Output

{"name": "Dell Alienware", "processor": "Intel Core i7"}

2. Convert Class Object with Multiple Data Types to JSON

Here, we define a Python class with various data types (string, int, float), create an object of this class, and then convert it to a JSON string.

Python Program

import json

class Laptop:
	def __init__(self, name, processor, hdd, ram, cost):
		self.name = name
		self.processor = processor
		self.hdd = hdd
		self.ram = ram
		self.cost = cost
		
#create object
laptop1 = Laptop('Dell Alienware', 'Intel Core i7', 512, 8, 2500.00)

#convert to JSON string
jsonStr = json.dumps(laptop1.__dict__)

#print JSON string
print(jsonStr)

Explanation:

  1. The Laptop class is initialized with multiple data types: name (string), processor (string), hdd (int), ram (int), and cost (float).
  2. We create an object laptop1 with these values and then convert the object’s attributes to a JSON string using json.dumps(laptop1.__dict__).
  3. The method converts the class object into a JSON string, where the attributes are converted into JSON key-value pairs.

Output

{"name": "Dell Alienware", "processor": "Intel Core i7", "hdd": 512, "ram": 8, "cost": 2500.0}

3. Convert Class Object with Nested Object to JSON

In this example, we will show how to convert a class object containing another class object as an attribute into a JSON string.

Python Program

import json

class Processor:
	def __init__(self, brand, speed):
		self.brand = brand
		self.speed = speed

class Laptop:
	def __init__(self, name, processor, hdd, ram, cost):
		self.name = name
		self.processor = processor
		self.hdd = hdd
		self.ram = ram
		self.cost = cost

# Create a nested object for processor
processor = Processor('Intel', '3.5 GHz')

# Create a Laptop object
laptop1 = Laptop('Dell Alienware', processor, 512, 8, 2500.00)

# Convert to JSON string
jsonStr = json.dumps(laptop1.__dict__, default=lambda o: o.__dict__)

# Print JSON string
print(jsonStr)

Explanation:

  1. The Laptop class now contains an instance of the Processor class as its attribute.
  2. To convert this nested object to JSON, we use the default=lambda o: o.__dict__ argument in the json.dumps() method. This tells Python how to handle custom objects like Processor.
  3. This method recursively converts the nested object to a dictionary before converting it to JSON.

Output

{"name": "Dell Alienware", "processor": {"brand": "Intel", "speed": "3.5 GHz"}, "hdd": 512, "ram": 8, "cost": 2500.0}

Summary

In this tutorial, we learned how to convert a Python Class Object to a JSON String using json.dumps(). We explored examples for simple class objects, class objects with various data types, and even class objects with nested objects. These methods help in converting Python objects into a JSON-compatible format that can be easily saved or transmitted.

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