问题描述

我有一个画布应用程序 (http://apps.facebook.com/myapp)，其他页面(企业等)可以将它添加到他们的页面.在我的应用中，我如何知道我是从哪个页面被调用的?

I have a canvas app (http://apps.facebook.com/myapp) and other pages (businesses, etc) can Add it to their page. Within my app, how can I know which page I'm being called from?

我使用的是 PHP-SDK

I'm using the PHP-SDK

推荐答案

如 Facebook 页面中所述标签教程:

当用户导航到 Facebook 时页面，他们会看到你的页面标签添加在下一个可用选项卡中位置.从广义上讲，页面选项卡是以完全相同的方式加载画布页面.当用户选择您的页面选项卡，您将收到signed_request 参数为 1附加参数，page.这参数包含一个 JSON 对象一个 id(当前的页面 id页面)，管理员(如果用户是管理员页面)，并喜欢(如果用户已喜欢该页面).和画布一样页面，您将不会收到所有您可以访问的用户信息应用程序在signed_request 中，直到用户授权您的应用程序.

When a user navigates to the Facebook Page, they will see your Page Tab added in the next available tab position. Broadly, a Page Tab is loaded in exactly the same way as a Canvas Page. When a user selects your Page Tab, you will received the signed_request parameter with one additional parameter, page. This parameter contains a JSON object with an id (the page id of the current page), ***** (if the user is a ***** of the page), and liked (if the user has liked the page). As with a Canvas Page, you will not receive all the user information accessible to your app in the signed_request until the user authorizes your app.

因此，捕获页面 ID 的一种方法是:

So one way to capture the page id would be:

<?php
// PATH TO FB-PHP-SDK
require '../../src/facebook.php';

$facebook = new Facebook(array(
  'appId'  => 'APP_ID',
  'secret' => 'APP_SECRET',
  'cookie' => true,
));
$signed_request = $facebook->getSignedRequest();
if( $page = $signed_request['page'] ) {
    echo $page['id'];
}
?>

或者没有 PHP-SDK 的解决方案:

OR a solution without the PHP-SDK:

<?php
if(!empty($_REQUEST["signed_request"])) {
    $app_secret = "APP_SECRET";
    $data = parse_signed_request($_REQUEST["signed_request"], $app_secret);

    if (isset($data["page"])) {
        echo $data["page"]["id"];
    } else {
        echo "Not in a page";
    }
}

function parse_signed_request($signed_request, $secret) {
    list($encoded_sig, $payload) = explode('.', $signed_request, 2); 

    // decode the data
    $sig = base64_url_decode($encoded_sig);
    $data = json_decode(base64_url_decode($payload), true);

    if (strtoupper($data['algorithm']) !== 'HMAC-SHA256') {
        error_log('Unknown algorithm. Expected HMAC-SHA256');
        return null;
    }

    // check sig
    $expected_sig = hash_hmac('sha256', $payload, $secret, $raw = true);
    if ($sig !== $expected_sig) {
        error_log('Bad Signed JSON signature!');
        return null;
    }

    return $data;
}

function base64_url_decode($input) {
    return base64_decode(strtr($input, '-_', '+/'));
}