当使用Facebook Graph API返回超过500个元素（如朋友列表）时，需要进行分页。有什么好办法呢？
答案 0 :(得分：2)
以下是我在自己的应用上使用分页的方式。
http://developsocialapps.com/facebook-friends-list-and-paging/
该库具有所需的大部分代码。主要方法是 getGraphObjectWithPaging 。它使用图API获取对象，然后只要响应中有下一页或达到$ maxpages，就会保持循环。一个特点是有时Facebook会将下一页作为您刚刚获得的同一页面返回，因此它会检查这一点并在此时停止。
class FacebookApp {
public $appId;
private $appSecret;
private $nameSpace;
public $userId;
public $token;
public $tokenExpires;
// get your own from http://www.w3.org/P3P/
public $p3p = 'P3P:CP="IDC DSP COR ADM DEVi TAIi PSA PSD IVAi IVDi CONi HIS OUR IND CNT"';
/* construct object
appid, secret, and namespace from app settings */
public function __construct($id, $secret, $namespace) {
$this->appId = $id;
$this->appSecret = $secret;
$this->nameSpace = $namespace;
}
/* return json data from a graph api object using paging
$object = object to get
limit = limit parameter for API object
maxpages = maximum number of pages to get */
function getGraphObjectWithPaging($object,$limit=500,$maxpages=10) {
$data = array();
$url = $this->getGraphUrl($object,$limit);
// loop through API calls until maxpages or no paging->next
while ($maxpages > 0) {
$response = $this->makeCurlRequest($url);
if ($repsonse === false) {
// something went wrong
break;
} else {
$jsonarray = json_decode($response,true);
if (isset($jsonarray['error'])) {
// something went wrong
break;
} else {
// add current data to data array
$data = array_merge ($data,$jsonarray['data']);
if (isset($jsonarray['paging']['next'])) {
if ($url == $jsonarray['paging']['next']) {
// for some reason facebook sometimes returns a next url which is the same as we just got, so exit here
break;
} else {
// keep looping
$url = $jsonarray['paging']['next'];
$maxpages--;
}
} else {
// no more pages
break;
}
}
}
}
return array("data"=>$data); // using data so it is the same format as other API repsonses
}
/* constructs graphs url */
public function getGraphUrl($object,$limit=false) {
$url = "https://graph.facebook.com/".$object;
if (strpos($url,"?") === false) $url .= "?";
else $url .= "&";
$url .= "access_token=".$this->token;
if ($limit !== false) $url .= "&limit=".$limit;
return $url;
}
/* uses curl to get a url, use $postarray to make a post, otherwise it will get */
public function makeCurlRequest($url,$postarray=false) {
$return = false;
try {
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_HEADER, false);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
if($postarray !== false){
curl_setopt ($ch, CURLOPT_POST, true);
curl_setopt ($ch, CURLOPT_POSTFIELDS, $postarray);
}
$response = curl_exec($ch);
$responseInfo = curl_getinfo($ch);
curl_close($ch);
if ($responseInfo['http_code']==200) {
$return = $response;
}
} catch (Exception $e) {
$return = false;
}
return $return;
}
/* sets userid and token from signed request, return true or false if authorized */
public function initOauthUserFromSignedRequest() {
$authorized = false;
if (isset($_REQUEST['signed_request'])) {
$data = $this->parseSignedRequest($_REQUEST['signed_request']);
if ($data !== false) {
if (isset($data['user_id']) && isset($data['oauth_token'])) {
$this->userId = $data['user_id'];
$this->token = $data['oauth_token'];
$this->tokenExpires = $data['expires'];
$authorized = true;
}
}
}
return $authorized;
}
/* require user to authorize and have permissions for page
redirect_uri = url to return after user has authorized like redirect.php
success_uri = url to redirect to on successful authorization like mypage.php
scope = comma separted list of permissions */
function requireAuthorization($redirect_uri,$success_uri=false,$scope=false) {
if ($success_uri === false) {
// if no success_uri use current page, all files for app must be in same directory
$success_uri = substr($_SERVER['REQUEST_URI'],strrpos($_SERVER['REQUEST_URI'],"/")+1);
}
$this->setCookie ("success_uri",$success_uri,0); // we will use this on the redirect_uri page
$requireauth = true;
if ($this->initOauthUserFromSignedRequest()) { // user has authorized
if (($scope === false) || ($this->hasAllPermissions($scope))) { // now check for perms
$requireauth = false;
}
}
if ($requireauth) { // user is either not authorized or doesn't have permissions
$url = $this->getAuthUrl($this->getCanvasUrl($redirect_uri),$scope);
echo "<html>\n<body>\n<script>\ntop.location.href='".$url."';\n</script></body></html>";
exit();
}
}
/* checks to see if has permissions, scope is comma separated list */
public function hasAllPermissions($scope) {
$return = false;
$cookiename = "permissions_".$this->appId."_".$this->userId;
$requiredpermissions = explode(",",$scope);
// first check cookie
if (isset($_COOKIE[$cookiename])) {
$return = true;
$permissions = json_decode($_COOKIE[$cookiename],true);
foreach ($requiredpermissions as $perm) {
if ($permissions['data'][0][$perm] != 1) {
$return = false;
break;
}
}
}
// if didn't have all in cookie, then see if it is in graph
if ($return == false) {
$permissions = $this->getGraphObject("me/permissions");
if ($permissions !== false) {
$this->setCookie($cookiename,json_encode($permissions),0);
$return = true;
foreach ($requiredpermissions as $perm) {
if ($permissions['data'][0][$perm] != 1) {
$return = false;
break;
}
}
}
}
return $return;
}
/* sets a cookie with p3p headers */
public function setCookie($name,$value,$expires) {
if ($this->p3p != '') {
header($this->p3p);
$this->p3p = '';
}
setcookie ($name,$value,$expires,"/");
}
/* returns url for oauth authorization
redirect_uri = url to return after user has authorized
scope = comma separted list of permissions */
public function getAuthUrl($redirect_uri,$scope=false) {
$url = "https://www.facebook.com/dialog/oauth/?client_id=".$this->appId."&redirect_uri=".rawurlencode($redirect_uri);
if ($scope !== false) $url .= "&scope=".rawurlencode($scope);
return $url;
}
/* returns url to app canvas page, $page like mypage.php?foo=bar */
public function getCanvasUrl($page) {
if ($_SERVER['HTTPS'] == "on") $protocol = "https";
else $protocol = "http";
return $protocol."://apps.facebook.com/".$this->nameSpace."/".$page;
}
/* parses signed_request parameter and returns data object, returns false if sigs don't match */
public function parseSignedRequest($signed_request) {
list($encoded_sig, $payload) = explode('.', $signed_request, 2);
$data = json_decode(base64_decode(strtr($payload, '-_', '+/')), true);
$sig = base64_decode(strtr($encoded_sig, '-_', '+/'));
$expected_sig = hash_hmac('sha256', $payload, $this->appSecret, true);
if ($sig == $expected_sig) {
return $data;
} else {
return false;
}
}
}
以下是如何在页面上使用它：
$facebookapp = new FacebookApp($GLOBALS['facebookAppId'],$GLOBALS['facebookAppSecret'],$GLOBALS['facebookNamespace']);
$facebookapp->requireAuthorization($GLOBALS['facebookRedirectPage']);
$friends = $facebookapp->getGraphObjectWithPaging("me/friends");