Introduction to JSON

What is JSON?

JSON (JavaScript Object Notation) is a lightweight data-interchange format. Mostly it is used to transfer data between computers.

Characteristics of JSON

• Lightweight: JSON is designed to be easy to use and quick to interpret, making it ideal for data interchange.
• Self-describing: JSON structures are clear and understandable, making it easy to read and write.
• Language Independent: Although derived from JavaScript, JSON is language-independent, with many programming languages providing support for parsing and generating JSON data.

Use Cases of JSON

• App and Web Development: JSON is extensively used in app and web development for transferring data between a server and a client.
• APIs and Web Services: Many web services and APIs exchange data using JSON format due to its straightforward and efficient structure.

JSON Data Types

JSON supports various data types, including:

• String: A sequence of characters wrapped in quotes.
• Number: Numeric data (integer or floating point).
• Boolean: Represents a truth value (true or false).
• Null: Represents a null value.
• Array: An ordered list of values, enclosed in square brackets [].
• Object: A collection of key-value pairs, enclosed in curly braces {}.

JSON Syntax Rules

• Data is in name/value pairs.
• Curly braces {} hold objects, while square brackets [] hold arrays.
• Data is separated by commas, and each name in an object is followed by a colon : which precedes the value.

Example of JSON Data:

{
  "name": "John Doe",
  "age": 30,
  "isEmployed": true,
  "address": {
    "street": "123 Main St",
    "city": "Anytown"
  },
  "phoneNumbers": ["123-456-7890", "456-789-0123"]
}

JSON vs. XML

JSON and XML are both used for data interchange, but JSON is generally preferred due to its simpler syntax, faster parsing, and lighter data format.

Parsing JSON with Dart

To parse JSON in Dart, you can use the jsonDecode function from the dart:convert package.

Example of Parsing JSON in Dart:

import 'dart:convert';

void main() {
  String jsonString = '''
  {
    "name": "John Doe",
    "age": 30,
    "isEmployed": true
  }
  ''';

  var decodedJson = jsonDecode(jsonString);

  print('Name: ${decodedJson['name']}');
  print('Age: ${decodedJson['age']}');
  print('Is Employed: ${decodedJson['isEmployed']}');
}