JSON With PHP

Let's begin with making ready the environment to begin our programming with PHP for JSON. A common use of JSON is to examine data from a web server and display the data on a web page.

This chapter will train you on the way to exchange JSON data among the client and a PHP server.

Environment

As of PHP 5.2.0, the JSON extension is bundled and compiled into PHP by default.

JSON Function

Encoding JSON in PHP (json_encode)

PHP json_encode() function is made in use for encoding JSON in PHP. This function gives back the JSON representation of a value on success or FALSE on failure.

Syntax

string json_encode ( $value [, $options = 0 ] )

Parameters

• value − The value being encoded. This function only works with UTF-8 encoded data.
• options − This optional value is a bitmask consisting of JSON_HEX_QUOT, JSON_HEX_TAG, JSON_HEX_AMP, JSON_HEX_APOS, JSON_NUMERIC_CHECK, JSON_PRETTY_PRINT, JSON_UNESCAPED_SLASHES, JSON_FORCE_OBJECT.

Example

How to convert an array into JSON with PHP, Lets examine with the below given example:

<?php
   $arr = array('a' => 1, 'b' => 2, 'c' => 3, 'd' => 4, 'e' => 5);
   echo json_encode($arr);
?>
While carry out, this will generate the below given result:
{"a":1,"b":2,"c":3,"d":4,"e":5}
How the PHP objects can be transfered into JSON with the below given example:
<?php
   class Emp {
      public $name = "";
      public $hobbies  = "";
      public $birthdate = "";
   }
   $e = new Emp();
   $e->name = "sachin";
   $e->hobbies  = "sports";
   $e->birthdate = date('m/d/Y h:i:s a', "8/5/1974 12:20:03 p");
   $e->birthdate = date('m/d/Y h:i:s a', strtotime("8/5/1974 12:20:03"));

   echo json_encode($e);
?>

After applying, it will generate the below given result:

{"name":"sachin","hobbies":"sports","birthdate":"08\/05\/1974 12:20:03 pm"}

Decoding JSON in PHP (json_decode)

PHP json_decode() function is made in use for decoding JSON in PHP. This function gives back the value decoded from json to appropriate PHP type.

Syntax

mixed json_decode ($json [,$assoc = false [, $depth = 512 [, $options = 0 ]]])

Parameters

• json_string − It is an encoded string which must be UTF-8 encoded data.
• assoc − It is a boolean type parameter, when set to TRUE, returned objects will be converted into associative arrays.
• depth − It is an integer type parameter which specifies recursion depth
• options − It is an integer type bitmask of JSON decode, JSON_BIGINT_AS_STRING is supported.

Example

How PHP can be used to decode JSON objects, Let’s examine the below given example:

<?php
   $json = '{"a":1,"b":2,"c":3,"d":4,"e":5}';
   var_dump(json_decode($json));
   var_dump(json_decode($json, true));
?>
After applying, you will get the below given result:
object(stdClass)#1 (5) {
   ["a"] => int(1)
   ["b"] => int(2)
   ["c"] => int(3)
   ["d"] => int(4)
   ["e"] => int(5)
}
array(5) {
   ["a"] => int(1)
   ["b"] => int(2)
   ["c"] => int(3)
   ["d"] => int(4)
   ["e"] => int(5)
}

The PHP File:

PHP has few functions that is built to manage JSON.

Objects in PHP can be transformed into JSON by make use of the PHP function json_encode():

PHP File

<?php
$myObj->name = "John";
$myObj->age = 30;
$myObj->city = "New York";
$myJSON = json_encode($myObj);
echo $myJSON;
?>

The Client JavaScript

JavaScript on the client, by making use of an AJAX call to request the PHP file from the instance given below:

Example

const xmlhttp = new XMLHttpRequest();
xmlhttp.onload = function() {
  const myObj = JSON.parse(this.responseText);
  document.getElementById("demo").innerHTML = myObj.name;
}
xmlhttp.open("GET", "demo_file.php");
xmlhttp.send();

PHP Array

Arrays in PHP will also be transformed into JSON when making use of the PHP function json_encode():

PHP File

<?php
$myArr = array("John", "Mary", "Peter", "Sally");

$myJSON = json_encode($myArr);

echo $myJSON;
?>

The Client JavaScript

JavaScript on the client, by making use of an AJAX call to request the PHP file from the array instance given above:

Example

Use JSON.parse() to transform the result into a JavaScript array:

var xmlhttp = new XMLHttpRequest();
xmlhttp.onload = function() {
  const myObj = JSON.parse(this.responseText);
  document.getElementById("demo").innerHTML = myObj[2];
}
xmlhttp.open("GET", "demo_file_array.php", true);
xmlhttp.send();

PHP Database

PHP is a server-aspect programming language and may be used to get entry to a database.

Imagine you've got a database for your server, and also you need to send a request to it from the client wherein you ask for the 10 first rows in a table called "customers".

On the client, make a JSON object that describes the numbers of rows you need to return.

Before you send the request to the server, convert the JSON object right into a string and send it as a parameter to the URL of the PHP page:

Example:

Use JSON.stringify() to transform the JavaScript object into JSON:

const limit = {"limit":10};
const dbParam = JSON.stringify(limit);
xmlhttp = new XMLHttpRequest();
xmlhttp.onload = function() {
  document.getElementById("demo").innerHTML = this.responseText;
}
xmlhttp.open("GET","json_demo_db.php?x=" + dbParam);
xmlhttp.send();