awesome-copilot/skills/create-web-form/references/php-json.md

PHP JSON Reference

Source: https://www.w3schools.com/php/php_json.asp

What is JSON?

JSON stands for JavaScript Object Notation and is a syntax for storing and exchanging data. JSON is a text format that is completely language independent. Since the JSON format is text only, it can easily be sent to and from a server, and used as a data format by any programming language.

PHP has some built-in functions to handle JSON:

• json_encode() -- Encodes a value to JSON format
• json_decode() -- Decodes a JSON string into a PHP variable

json_encode() -- Encoding PHP to JSON

The json_encode() function is used to encode a value to JSON format (a valid JSON string).

Encoding an Associative Array

<?php
$age = array("Peter" => 35, "Ben" => 37, "Joe" => 43);

echo json_encode($age);
?>

Output:

{"Peter":35,"Ben":37,"Joe":43}

Encoding an Indexed Array

<?php
$cars = array("Volvo", "BMW", "Toyota");

echo json_encode($cars);
?>

Output:

["Volvo","BMW","Toyota"]

Encoding a PHP Object

<?php
$myObj = new stdClass();
$myObj->name = "John";
$myObj->age = 30;
$myObj->city = "New York";

echo json_encode($myObj);
?>

Output:

{"name":"John","age":30,"city":"New York"}

json_decode() -- Decoding JSON to PHP

The json_decode() function is used to decode a JSON string into a PHP object or associative array.

Syntax

json_decode(string, assoc, depth, options)

Parameters

Parameter	Description
string	Required. Specifies the JSON string to be decoded.
assoc	Optional. If set to true, the returned object will be converted into an associative array. Default is false.
depth	Optional. Specifies the maximum recursion depth. Default is 512.
options	Optional. Specifies a bitmask (e.g., JSON_BIGINT_AS_STRING).

Decoding JSON into a PHP Object (default)

By default, the json_decode() function returns an object:

<?php
$jsonobj = '{"Peter":35,"Ben":37,"Joe":43}';

$obj = json_decode($jsonobj);

echo $obj->Peter;  // Outputs: 35
echo $obj->Ben;    // Outputs: 37
echo $obj->Joe;    // Outputs: 43
?>

Decoding JSON into an Associative Array

When the second parameter is set to true, the JSON string is decoded into an associative array:

<?php
$jsonobj = '{"Peter":35,"Ben":37,"Joe":43}';

$arr = json_decode($jsonobj, true);

echo $arr["Peter"];  // Outputs: 35
echo $arr["Ben"];    // Outputs: 37
echo $arr["Joe"];    // Outputs: 43
?>

Accessing Decoded Values

From an Object

Use the arrow (->) operator to access values from a decoded object:

<?php
$jsonobj = '{"Peter":35,"Ben":37,"Joe":43}';

$obj = json_decode($jsonobj);

echo $obj->Peter;
echo $obj->Ben;
echo $obj->Joe;
?>

From an Associative Array

Use square bracket syntax to access values from a decoded associative array:

<?php
$jsonobj = '{"Peter":35,"Ben":37,"Joe":43}';

$arr = json_decode($jsonobj, true);

echo $arr["Peter"];
echo $arr["Ben"];
echo $arr["Joe"];
?>

Looping Through Values

Looping Through an Object

Use a foreach loop to loop through the values of a decoded object:

<?php
$jsonobj = '{"Peter":35,"Ben":37,"Joe":43}';

$obj = json_decode($jsonobj);

foreach($obj as $key => $value) {
    echo $key . " => " . $value . "<br>";
}
?>

Output:

Peter => 35
Ben => 37
Joe => 43

Looping Through an Associative Array

Use a foreach loop to loop through the values of a decoded associative array:

<?php
$jsonobj = '{"Peter":35,"Ben":37,"Joe":43}';

$arr = json_decode($jsonobj, true);

foreach($arr as $key => $value) {
    echo $key . " => " . $value . "<br>";
}
?>

Output:

Peter => 35
Ben => 37
Joe => 43