What is the purpose of using the getSignedRequest function in PHP when developing a Facebook app?

The getSignedRequest function in PHP is used when developing a Facebook app to retrieve the signed request parameter sent by Facebook when a user accesses the app. This parameter contains information about the user and their session, such as their user ID and access token. By using the getSignedRequest function, developers can securely access this information and personalize the app experience for each user. 

// Get the signed request parameter from Facebook
$signed_request = $_REQUEST['signed_request'];

// Decode the signed request to obtain the user data
$decoded_signed_request = base64_url_decode(explode('.', $signed_request)[1]);
$user_data = json_decode($decoded_signed_request, true);

// Access the user ID and access token from the user data
$user_id = $user_data['user_id'];
$access_token = $user_data['oauth_token'];

// Function to decode base64 URL encoded string
function base64_url_decode($input) {
    return base64_decode(strtr($input, '-_', '+/'));
}

Keywords

getSignedRequest PHP Facebook app development function

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