An Introduction To JSON

Introduction to JSON

In this article we will discuss the first two points from the following. In upcoming articles, I will discuss how to create a JSON file from database table.

  • Introduction to JSON
  • JSON syntax
  • Parsing and Generating JSON files
  • JSON data storage application

So let us start with the introduction part.

What is JSON?

JSON (JavaScipt Object Notation) is a lightweight data-interchange format.

Why use it

  • Same syntax as JavaScript objects.
  • Easy for humans to read and write.
  • Language independent.
  • Can be used to store application data.

How can we create /read JSON file

We can create/read JSON file by using:

  • JavaScriptSerializer (inbuilt in dotnet framework).
  • JSON.NET third party tool (download from Nuget package Manager).

So let us look at JSON:

{ } culry braces represent object
key – value pair


JSON Syntax

So what exactly makes up a JSON file:

  • Values
  • Objects
  • Arrays
  • Putting it all together

JSON Values can be:

  • Strings ( in double quotes)
  • Numbers (integer or floating point)
  • Boolean ( true or false )
  • Objects ( in curly brackets)
  • Array( in square brackets)
  • Null

JSON Object

  • Name/value pairs using colons
  • Enclose by curly braces
  • Pairs separated by commas

Example

  1. {  
  2.    name: values,  
  3.    name2: values2  
  4. }  
So here is a very simple example curly braces representing json object, name values pair separated by comma:
  1. {  
  2.    "Name" :"Ravi",  
  3.    "City""Varanasi",  
  4. }  
More complex example
  1. {  
  2.    "countryId": 1,  
  3.    "countryName" : "India",  
  4.    "state" : ["uttar pradesh","Mumbai","Bangalore"]  
  5. }  
Again we have curly braces representing object. This time we have three name value pairs: countryId is just integer, countryName is string and state is arrays shown by bracket,

JSON Arrays
  • Values enclosed by brackets
  • Seprated by commas [item,item,item,item]

Example

["uttar pradesh","Mumbai","Bangalore"]

Indicated by bracket we have json arrays and in this example its an array of three string and each string separated by commas:

[1,2,3,4] its array of number

Complex array

  1. [  
  2. {  
  3.     "AlbumId": 3,  
  4.     "GenreId": 1,  
  5.     "ArtistId": 4,  
  6. },  
  7. {  
  8.     "AlbumId": 5,  
  9.     "GenreId": 1,  
  10.     "ArtistId": 77,  
  11. }]  
So array can be collection of anything including object and these object have three name value pair.

Putting it all together,

 

  • JSON values can also be objects or arrays
  • JSON objects and arrays can be nested

Points of Interest

  • In this article, I have touched very basic of JSON.
  • JSON is very useful in client server communication where network bandwidth is very limited.