Serialization - JSON

Serialization - JSON#

JSON serialization is the process of converting complex data structures, like objects or arrays, into a simple text format called JSON (JavaScript Object Notation). This text-based representation is easy to store, transmit, and parse.

Why Use JSON Serialization?#

  • Data Exchange: It’s widely used for data interchange between different systems and applications.

  • Data Storage: JSON files can be used to store data persistently.

  • Data Transmission: It’s efficient for sending data over networks.

  • Readability: JSON is human-readable, making it easy to inspect and debug.

How Does It Work?#

  1. Data Structure: You have a complex data structure, like an object with properties and values.

  2. Serialization: A serializer converts this data structure into a JSON string. This string adheres to specific JSON syntax rules.

  3. Transmission or Storage: The JSON string can be sent over a network or stored in a file.

  4. Deserialization: When you need to use the data again, a deserializer converts the JSON string back into its original data structure.

Key Points#

  • JSON is a lightweight data-interchange format.

  • Serialization converts data to JSON, deserialization converts JSON back to data.

  • Widely used in web applications, APIs, and data storage.

Lecture Code#

import json

# Define a class to represent a person with name, city, state
class Person:
  def __init__(self, name, city, state):
    self.name   = name
    self.city   = city
    self.state  = state

# Function to serialize a list of people to JSON
def serialize_to_json(people):
  data = []
  for person in people:
    data.append({"name": person.name, "city": person.city,"state":person.state})
  with open("people.json", "w") as f:
    json.dump(data, f)

# Function to deserialize JSON data back to a list of people
def deserialize_from_json():
  people = []
  try:
    with open("people.json", "r") as f:
      data = json.load(f)
    for item in data:
      people.append(Person(item["name"], item["city"],item["state"]))
  except FileNotFoundError:
    print("Error: 'people.json' file not found.")
  return people

def main():
  # Example usage
  people = [ Person("Alice",    "Albany",   "AL"), 
            Person("Bob",      "Boston", "MT"),
            Person("Charlie",  "Chico",  "IL"),
            Person("Gwen",     "Gaines",  "GA"),
            Person("James",    "Jordon",   "MT")]


  serialize_to_json(people)

  deserialized_people = deserialize_from_json()

  # Print the deserialized data
  for person in deserialized_people:
    print(f"Name: {person.name}, " +   
          f"\t{person.city}, " + 
          f"\t\t{person.state}")

main()

'''
JSON FILE
people.json
(Note the output below has been prettified for readablity)

[
{"name": "Alice", "city": "Albany", "state": "AL"}, 
{"name": "Bob", "city": "Boston", "state": "MT"}, 
{"name": "Charlie", "city": "Chico", "state": "IL"}, 
{"name": "Gwen", "city": "Gaines", "state": "GA"}, 
{"name": "James", "city": "Jordon", "state": "MT"}
]

-----------
Output
Name: Alice,    Albany,         AL
Name: Bob,      Boston,         MT
Name: Charlie,  Chico,          IL
Name: Gwen,     Gaines,         GA
Name: James,    Jordon,         MT

'''

Code Summary#

Person Class:

  • Defines a Person class with attributes name, city, and state.

serialize_to_json Function:

  • Takes a list of Person objects as input.

  • Iterates through the list, creating dictionaries for each person with their attributes as key-value pairs.

  • Creates a list data containing these dictionaries.

  • Opens a file named “people.json” in write mode ("w").

  • Uses json.dump to convert the data list to a JSON string and write it to the file.

deserialize_from_json Function:

  • Initializes an empty list people to store deserialized Person objects.

  • Tries to open “people.json” in read mode ("r").

  • If successful, uses json.load to read the JSON data from the file and store it as a list in data.

  • Iterates through the data list (containing dictionaries).

  • For each dictionary, creates a new Person object using the values for “name”, “city”, and “state”.

  • Appends the created Person object to the people list.

  • If the file is not found, it catches a FileNotFoundError and prints an error message.

  • Finally, returns the list of deserialized Person objects.

main Function:

  • Creates a sample list of Person objects with names, cities, and states.

  • Calls serialize_to_json to convert this list to JSON and store it in “people.json”.

  • Calls deserialize_from_json to read the data back from “people.json” and get a list of deserialized Person objects.

  • Prints the information of each deserialized person (name, city, state) in a formatted way.

Contents