JSON PHP

A common use of JSON is to send data to the web server/Read data from the web server and display data in a web page.

This chapter introduces how to exchange JSON data between the client and PHP server.

PHP JSON functions

PHP5.2version 5.4.0 and above have built-in JSON extension.

PHP has the following built-in functions to handle JSON:

json_encode() function

PHP functions can be used to convert PHP objects to JSON json_encode().

The given file is json_demo1.php save:

　　<?php
　　$myObj = new stdClass();
　　$myObj->name = "Seagull";
　　$myObj->age =　22;
　　$myObj->city = "New Delhi";
　　$myJSON = json_encode($myObj);　　/*　Convert PHP object to JSON string　*/
　　
　　echo $myJSON;
　　?>

The following example requests a PHP file (json_demo1Then use JSON.parse() to convert the response to a JavaScript object (json_demo

var httpRequest = new XMLHttpRequest();
httpRequest.onreadystatechange = function() {
　　　if (this.readyState ====　4　&& this.status ===　200) {
　　　　　　var myObj = JSON.parse(this.responseText);　//　Convert JSON string to Object
　　　　　　document.getElementById("output").innerHTML = myObj.name;
　　　}
});
httpRequest.open("GET", "json_demo1.php", true);
httpRequest.send();

Using PHP functions, PHP arrays can also be converted to JSON json_encode().

The given file is json_demo2.php save:

　　<?php
　　$myArr = array("Seagull", "Cynthia", "Tarush");
　　$myJSON = json_encode($myArr);　　/*　Convert PHP array to JSON string　*/
　　
　　echo $myJSON;
　　?>

The following example is taken from the above example (json_demo2request PHP file, and then use JSON.parse() to convert the response to a JavaScript array:

var httpRequest = new XMLHttpRequest();
httpRequest.onreadystatechange = function() {
　　　if (this.readyState ====　4　&& this.status ===　200) {
　　　　　　var myArr = JSON.parse(this.responseText);　//　Convert JSON string to array
　　　　　　document.getElementById("output").innerHTML = myArr[0];
　　　}
});
httpRequest.open("GET", "json_demo2.php", true);
httpRequest.send();

json_decode() function

JSON string can be converted to PHP object using the function json_decode().

The given file is saved by json_demo.php:

　　<?php
　　$q = $_REQUEST["q"];　　//　Get q parameter from URL
　　$obj = json_decode($q, false);　//　Convert JSON string to PHP object
　　echo $obj->name."  Lives in  ".$obj->city.".";
　　?>

The following example converts a JavaScript object to a JSON string and sends it to the server (demo_json.php):

var myObj = {name: "Seagull", age:　22, city: "New Delhi"};
var myJSON = JSON.stringify(myObj);
window.location = "json_demo.php?q="　+　myJSON;

You can use the function to convert JSON string to PHP array json_decode().

<?php
$q = $_REQUEST["q"];　　//Get q parameter from URL
$arr = json_decode($q, true);　//　Convert JSON string to PHP array
echo $arr["name"]."  Lives in  ".$arr["city"].".";
?>