追加变量到每个结果

Question

我为我的框架使用Codeigniter，并且我已经去了文档，我还没有找到解决方案。

既然我已经从数据库中选择了数据，我需要在每个检索到的记录末尾显示距离。

Example of json: {"details":[{"country":"United States","_id":"3892","lat":"39.954559","lng":"-82.837608","admin_level_1":"Ohio","locale":"Columbus"}]} 

这是它需要的，请记住，距离不在数据库中，它是在飞行中计算的。

Example of json: {"details":[{"country":"United States","_id":"3892","lat":"39.954559","lng":"-82.837608","admin_level_1":"Ohio","locale":"Columbus", "distance": "1.2 Mi"}]} 

任何关于如何获得距离的距离被追加到每个结果的末尾？

 $dbStations->select('lat'); 
     $dbStations->select('lng'); 
     $dbStations->select('_id'); 
     $stations = $dbStations->get('stDetails'); 
     foreach ($stations->result() as $station) { 
      $lat2 = $station->lat; 
      $lng2 = $station->lng; 
      $stId = $station->_id; 
      $distance = $this->distance->gpsdistance($lat1, $lng1, $lat2, $lng2, "M"); 
       if ($distance <= $rad) { 
       //at this point the code has determined that this id is within 
       //the preferred distance. 
       $stationArr[] = $stId; 
      } 
     } 
      $dbStations->select('country, _id, lat, lng, admin_level_1, locale'); 
      $dbStations->where_in('_id', $stationArr); 
      $stations = $dbStations->get('stationDetails'); 
     echo json_encode(array('stations' => $stations->result())); 
    } 

Answer 1

你可以尝试一次做所有事情。根据什么可能知道你的表格，这个查询应该给你在半径$rad内的电台。

必须定义变量$lat1和$lng1。

$query= "select country, _id, lat, lng, admin_level_1, locale, 
    (acos(sin(radians($lat1)) * sin(radians(lat)) + cos(radians($lat1)) * 
    cos(radians(lat)) * cos(radians($lng1) - radians(lng))) * 6378) 
    as distance 
    from stationDetails 
    where (acos(sin(radians($lat1)) * sin(radians(lat)) + 
      cos(radians($lat1)) * cos(radians(lat)) * cos(radians($lng1) - 
      radians(lng))) * 6378)<=$rad 
    order by distance desc"; 

echo json_encode($this->db->query($query)->result_array()); 

注：的距离以米为单位。

Answer 2

假设$dbStations->get('stDetails')和$dbStations->get('stationDetails')正在查询的同桌，你可以做这样的事情：

$dbStations->select('country, _id, lat, lng, admin_level_1, locale'); 
$stations = $dbStations->get('stDetails'); 

$output = array(); 

foreach ($stations->result() as $station) { 
    $lat2 = $station->lat; 
    $lng2 = $station->lng; 

    $distance = $this->distance->gpsdistance($lat1, $lng1, $lat2, $lng2, "M"); 

    if ($distance <= $rad) { 
     $station->distance = $distance; 
     $output[] = $station; 
    } 
} 

echo json_encode($output); 

我没有测试过这一点，它可能不会给你想要的，所以你可能要什么稍微调整一下。重要的是我如何做到这一点。在开始时抓取所有数据，然后验证每一行。如果该行有效（在一定距离内），则将该距离添加到该阵列并保存以输出。当没有更多的行时，输出有效的电台。