PHP JSON

advanced

Part of PHP Data & APIs

Theory

JSON (JavaScript Object Notation) is the most common data format for web APIs. PHP provides built-in functions to encode and decode JSON.

json_encode and json_decode

$array = ["name" => "Alice", "age" => 25, "skills" => ["PHP", "JavaScript"]];
 
// Convert PHP array to JSON string
$json = json_encode($array);
echo $json;
// {"name":"Alice","age":25,"skills":["PHP","JavaScript"]}
 
// Convert JSON string back to PHP array
$decoded = json_decode($json, true);  // true = associative array
echo $decoded["name"];  // Alice

The second parameter of json_decode() controls the return type:

true — returns an associative array
false (default) — returns a stdClass object

JSON Flags

json_encode($data, JSON_PRETTY_PRINT | JSON_UNESCAPED_UNICODE);

Common flags: JSON_PRETTY_PRINT, JSON_UNESCAPED_UNICODE, JSON_UNESCAPED_SLASHES, JSON_FORCE_OBJECT.

Fetching Data with file_get_contents

For simple GET requests:

$response = file_get_contents("https://api.example.com/data");
$data = json_decode($response, true);

Fetching Data with cURL

For more control (POST, headers, authentication):

cURL and JSON API Example

php

Error Handling

$json = '{"name": "Alice", age: 25}';  // Invalid JSON
$data = json_decode($json, true);
 
if (json_last_error() !== JSON_ERROR_NONE) {
    echo "JSON Error: " . json_last_error_msg();
}

Practical Examples

Example: JSON CRUD Operations

php

Exercises

Fetch and Display Posts from JSON API

easy

Use file_get_contents to fetch posts from JSONPlaceholder API (https://jsonplaceholder.typicode.com/posts?userId=1). Decode the JSON and display each post's title and body in an HTML list.

Expected Output:

An HTML page listing post titles and bodies fetched from the API