简单的一个方法:根据openid获取unionid
public function tmp_test(){
$httpTokenUrl = "https://api.weixin.qq.com/cgi-bin/token?gra【nt_type=client_credential&appid=您的appid&secret=你的密钥";
$ret = file_get_contents($httpTokenUrl);
$tmp = json_decode($ret, true);
$token = $tmp['access_token'];
$rows = M('users')->WHERE('unionid=""')->limit(10)->select();
foreach($rows as $itm){
$httpUnionIDUrl = "https://api.weixin.qq.com/cgi-bin/user/info?access_token=".$token."&openid=".$itm['openid']."&lang=zh_CN";
$ret = file_get_contents($httpUnionIDUrl);
$tmp = json_decode($ret, true);
M('users')->WHERE('user_id='.$itm['user_id'])->save(['unionid'=>$tmp['unionid']]);
}
}