How To Get The Body Of A JSON POST In PHP?

Using php://input to Access Raw POST Data

The php://input stream lets you access raw POST data. This stream is useful for JSON POST requests. Unlike $_POST, which doesn't work for JSON data, php://input allows you to read the raw request body.

To use php://input, you can use the file_get_contents() function:

$jsonData = file_get_contents('php://input');

This code reads the contents of the input stream, which contains the raw POST data.

if ($_SERVER['CONTENT_TYPE'] === 'application/json') {
    $jsonData = file_get_contents('php://input');
    // Process JSON data
} else {
    // Handle non-JSON requests
}

Decoding the JSON Data

After getting the raw JSON data, you need to decode it to use it in PHP. The json_decode() function changes the JSON string into a PHP object or array:

$data = json_decode($jsonData, true);

The second parameter (true) tells json_decode() to return an associative array instead of an object.

To handle JSON parsing errors, you can use this approach:

$data = json_decode($jsonData, true);
if (json_last_error() !== JSON_ERROR_NONE) {
    // Handle JSON decoding error
    $error = json_last_error_msg();
    // Log or display the error message
}

This code checks for JSON decoding errors and gets the error message if one occurs, allowing you to handle it in your application.

Using the STDIN Constant

In PHP, STDIN is a constant that represents the standard input stream. It's an open stream to php://input, providing another way to access raw POST data.

To use STDIN for reading JSON POST data, you can use the stream_get_contents() function:

$jsonData = stream_get_contents(STDIN);

This method works like file_get_contents('php://input'), but uses the STDIN constant instead.

Creating a Reusable Function for JSON POST Handling

To simplify JSON POST data handling, you can create a reusable function. This function can include error handling and validation:

function getJsonPostData() {
    // Check if the request method is POST
    if ($_SERVER['REQUEST_METHOD'] !== 'POST') {
        return ['error' => 'Only POST requests are allowed'];
    }

    // Check if the content type is JSON
    if (!isset($_SERVER['CONTENT_TYPE']) || strpos($_SERVER['CONTENT_TYPE'], 'application/json') === false) {
        return ['error' => 'Content-Type must be application/json'];
    }

    // Read the input
    $jsonData = file_get_contents('php://input');

    // Decode JSON
    $data = json_decode($jsonData, true);

    // Check for JSON decoding errors
    if (json_last_error() !== JSON_ERROR_NONE) {
        return ['error' => 'Invalid JSON: ' . json_last_error_msg()];
    }

    return $data;
}

You can use this function in your code like this:

$postData = getJsonPostData();
if (isset($postData['error'])) {
    // Handle error
    echo $postData['error'];
} else {
    // Process the valid JSON data
    // $postData now contains the decoded JSON
}

This function checks the request method, content type, reads the input, decodes the JSON, and handles potential errors. It provides a way to handle JSON POST data in your PHP applications.

function getJsonPostData($schema = null) {
    // ... existing code ...

    // If a schema is provided, validate the JSON data against it
    if ($schema !== null) {
        $validator = new JsonSchema\Validator;
        $validator->validate($data, $schema);

        if (!$validator->isValid()) {
            $errors = [];
            foreach ($validator->getErrors() as $error) {
                $errors[] = sprintf("[%s] %s", $error['property'], $error['message']);
            }
            return ['error' => 'JSON Schema validation failed: ' . implode(', ', $errors)];
        }
    }

    return $data;
}