PHP JSON Processing | Learn Computer Academy

Working with JSON in PHP

JSON is the standard format for exchanging data between a PHP backend and a frontend, or between two servers — nearly every API request and response uses it. PHP has JSON support built in, no package required.

PHP to JSON — json_encode()

$user = [
    'name' => 'Sam',
    'age' => 28,
    'active' => true,
];

echo json_encode($user);
// {"name":"Sam","age":28,"active":true}

Pretty-Printing for Readability

echo json_encode($user, JSON_PRETTY_PRINT);

JSON to PHP — json_decode()

By default, this returns an stdClass object — pass true as the second argument to get an associative array instead, usually the more convenient choice.

$json = '{"name":"Sam","age":28}';

$object = json_decode($json);
echo $object->name;        // Sam — object access

$array = json_decode($json, true);
echo $array['name'];        // Sam — array access

A Complete API Response Example

header('Content-Type: application/json');

$users = getUsersFromDatabase();   // an array of associative arrays

echo json_encode([
    'success' => true,
    'data' => $users,
]);

Checking for Errors

Invalid JSON makes json_decode() return null — worth checking explicitly, since a genuinely empty result also decodes to something falsy.

$data = json_decode($json);
if (json_last_error() !== JSON_ERROR_NONE) {
    die('Invalid JSON: ' . json_last_error_msg());
}

What json_encode() can't do

Not every PHP value converts cleanly — a resource (like an open file handle) can't be represented in JSON at all, and encoding one silently produces 0 rather than an error.