PHP JSON
Working with JSON data in PHP applications
📦 What is JSON?
JSON (JavaScript Object Notation) is a lightweight data format for storing and exchanging data. PHP provides built-in functions to encode PHP data into JSON and decode JSON back into PHP arrays or objects.
<?php
// PHP array to JSON
$data = ["name" => "John", "age" => 30];
$json = json_encode($data);
echo $json; // Output: {"name":"John","age":30}
?>
Output:
{"name":"John","age":30}
JSON Operations
json_encode()
Convert PHP arrays and objects into JSON strings for storage or API responses.
<?php
$user = [
"name" => "Alice",
"email" => "[email protected]"
];
$json = json_encode($user);
?>json_decode()
Parse JSON strings back into PHP arrays or objects for processing in your application.
<?php
$json = '{"name":"Bob","age":25}';
$data = json_decode($json, true);
echo $data["name"]; // Bob
?>JSON Options
Use flags to control JSON formatting like pretty printing, escaping, and Unicode handling.
<?php
$json = json_encode(
$data,
JSON_PRETTY_PRINT
);
?>Error Handling
Check for JSON errors using json_last_error() to handle invalid or malformed JSON data.
<?php
json_decode($json);
if (json_last_error() !== JSON_ERROR_NONE) {
echo "JSON Error!";
}
?>🔹 Encoding PHP to JSON
Convert PHP arrays into JSON strings using json_encode():
<?php
// Simple array
$colors = ["red", "green", "blue"];
$json1 = json_encode($colors);
echo "Array: $json1<br><br>";
// Associative array
$person = [
"name" => "John Doe",
"age" => 30,
"city" => "New York"
];
$json2 = json_encode($person);
echo "Object: $json2<br><br>";
// Nested array
$data = [
"user" => "Alice",
"scores" => [85, 90, 78]
];
$json3 = json_encode($data);
echo "Nested: $json3";
?>Output:
Array: ["red","green","blue"]
Object: {"name":"John Doe","age":30,"city":"New York"}
Nested: {"user":"Alice","scores":[85,90,78]}
🔹 Decoding JSON to PHP
Parse JSON strings back into PHP data structures:
<?php
$json = '{"name":"Bob","age":25,"city":"London"}';
// Decode as associative array
$array = json_decode($json, true);
echo "As Array:<br>";
echo "Name: {$array['name']}<br>";
echo "Age: {$array['age']}<br><br>";
// Decode as object
$object = json_decode($json);
echo "As Object:<br>";
echo "Name: {$object->name}<br>";
echo "City: {$object->city}";
?>Output:
As Array:
Name: Bob
Age: 25
As Object:
Name: Bob
City: London
🔹 Pretty Printing JSON
Format JSON with indentation for better readability:
<?php
$data = [
"name" => "Alice",
"email" => "[email protected]",
"address" => [
"street" => "123 Main St",
"city" => "Boston"
]
];
// Without pretty print
$compact = json_encode($data);
echo "Compact:<br>$compact<br><br>";
// With pretty print
$pretty = json_encode($data, JSON_PRETTY_PRINT);
echo "Pretty:<br><pre>$pretty</pre>";
?>Output:
Compact:
{"name":"Alice","email":"[email protected]","address":{"street":"123 Main St","city":"Boston"}}
Pretty:
{
"name": "Alice",
"email": "[email protected]",
"address": {
"street": "123 Main St",
"city": "Boston"
}
}
🔹 Working with JSON Files
Read from and write to JSON files:
<?php
// Data to save
$users = [
["id" => 1, "name" => "John"],
["id" => 2, "name" => "Jane"]
];
// Write to file
$json = json_encode($users, JSON_PRETTY_PRINT);
file_put_contents("users.json", $json);
echo "Data saved to users.json<br><br>";
// Read from file
$fileContent = file_get_contents("users.json");
$loadedUsers = json_decode($fileContent, true);
echo "Loaded users:<br>";
foreach ($loadedUsers as $user) {
echo "ID: {$user['id']}, Name: {$user['name']}<br>";
}
?>Output:
Data saved to users.json
Loaded users:
ID: 1, Name: John
ID: 2, Name: Jane
🔹 JSON Error Handling
Check for errors when encoding or decoding JSON:
<?php
// Invalid JSON
$invalidJson = '{"name":"Bob","age":}';
$result = json_decode($invalidJson);
if (json_last_error() !== JSON_ERROR_NONE) {
echo "JSON Error: " . json_last_error_msg() . "<br><br>";
}
// Valid JSON
$validJson = '{"name":"Bob","age":25}';
$result = json_decode($validJson);
if (json_last_error() === JSON_ERROR_NONE) {
echo "Valid JSON decoded successfully!<br>";
echo "Name: {$result->name}";
}
?>Output:
JSON Error: Syntax error
Valid JSON decoded successfully!
Name: Bob
🔹 JSON Encoding Options
Use flags to control JSON output format:
<?php
$data = [
"name" => "Alice",
"url" => "https://example.com/profile",
"tags" => ["php", "json", "api"]
];
// Default encoding
echo "Default:<br>";
echo json_encode($data) . "<br><br>";
// Don't escape slashes
echo "Unescaped slashes:<br>";
echo json_encode($data, JSON_UNESCAPED_SLASHES) . "<br><br>";
// Force object instead of array
echo "Force object:<br>";
echo json_encode($data["tags"], JSON_FORCE_OBJECT);
?>Output:
Default:
{"name":"Alice","url":"https:\/\/example.com\/profile","tags":["php","json","api"]}
Unescaped slashes:
{"name":"Alice","url":"https://example.com/profile","tags":["php","json","api"]}
Force object:
{"0":"php","1":"json","2":"api"}
🔹 Creating JSON APIs
Return JSON responses for API endpoints:
<?php
// Set JSON header
header('Content-Type: application/json');
// Sample API response
$response = [
"status" => "success",
"data" => [
"users" => [
["id" => 1, "name" => "John"],
["id" => 2, "name" => "Jane"]
]
],
"message" => "Users retrieved successfully"
];
// Output JSON
echo json_encode($response, JSON_PRETTY_PRINT);
?>Output:
{
"status": "success",
"data": {
"users": [
{"id": 1, "name": "John"},
{"id": 2, "name": "Jane"}
]
},
"message": "Users retrieved successfully"
}
🔹 Common JSON Options
Encoding Options:
- JSON_PRETTY_PRINT - Format with whitespace for readability
- JSON_UNESCAPED_SLASHES - Don't escape forward slashes
- JSON_UNESCAPED_UNICODE - Don't escape Unicode characters
- JSON_FORCE_OBJECT - Output objects instead of arrays
- JSON_NUMERIC_CHECK - Convert numeric strings to numbers
Common Errors:
- JSON_ERROR_NONE - No error occurred
- JSON_ERROR_SYNTAX - Syntax error, malformed JSON
- JSON_ERROR_DEPTH - Maximum stack depth exceeded
- JSON_ERROR_UTF8 - Malformed UTF-8 characters