如何从对象

Question

“任何” MongoDB的结果键我有一个PHP脚本，返回CSV格式的结果：

# cat query.php 
<?php 

include '../misc.php'; 
$values=$_GET?$_GET:$_POST; 

{ 
    $ts = isset($values['t'])?strtotime($values['t']):strtotime("-1 hour"); 
    $result=Query('iot.data',['key' => $values['key'], 'timestamp' => array('$gte' => $ts)],['projection' => array('_id' => 0, 'timestamp' => 1, $values['col'] => 1), 'sort' => array('timestamp' => 1)]); 

    if ($values['col'] == 'temp1') echo "Timestamp, Temperature\n"; 
    if ($values['col'] == 'BusV2') echo "Timestamp, Battery V\n"; 
    if ($values['col'] == 'uv1') echo "Timestamp, UV\n"; 


    foreach ($result as $r) { 
    $d = date('c',$r->timestamp); 
    if (isset($r->temp1)) echo "$d, $r->temp1\n"; 
    if (isset($r->BusV2)) echo "$d, $r->BusV2\n"; 
    if (isset($r->uv1)) echo "$d, $r->uv1\n"; 
    }; 
}; 

随着“山坳”参数我可以决定与时间戳返回了什么键。

如何在foreach循环中没有这些IF的情况下获得理想的结果？

如何将我的代码是这样的：如果我改变的foreach到

foreach ($result as $r) { 
    $d = date('c',$r->timestamp); 
    echo "$d, $r->$values['col']\n" // where object $r key comes from variable 'col' 
} 

它没有帮助： foreach ($result as $r => $v) {

因为$v没有得到关键$r值，$v是现在什么$r之前...

结果print_r($v);

stdClass Object 
(
    [temp1] => 25.2 
    [timestamp] => 1470304854 
) 

Answer 1

如果我理解你想要达到的目标，你可以使用：

foreach ($result as $r) { 
    $d = date('c',$r->timestamp);  
    echo "$d, " . $r->{$values['col']} . "\n"; 
}; 

看来你蒙戈返回一个stdClass Object，您可以访问使用->，这就是为什么$r[$values['col']]正在给500错误。