javascript - 动态 downloadURL( ) 调用

Question

我正在建立一个网站，其中包括照片库功能。在图库页面中，有一个带有多个标记的 map (谷歌)，每个标记都与特定的照片相关。

我的数据库中有一个“标记”表:

markers:  
id      | name     |  address | lat   | lng | gallery_id
_______________________________________________________
1       | ..       | ....     |..     | ..  | 2   
2       | ..       | ....     |..     | ..  | 2 
3       | ..       | ....     |..     | ..  | 3
4       | ..       | ....     |..     | ..  | 3
5       | ..       | ....     |..     | ..  | 10
...................... 

All the fields are populated with geolocated data and every row represents a specific photo uploaded by the user, all but gallery_id, that holds the id of the gallery that owns the photo.

In the gallery page there's the javascript to build up the google map:

<script type="text/javascript">

    function load() {
      var map = new google.maps.Map(document.getElementById("map"), {
        disableDefaultUI: true,
        scrollwheel: false,
        navigationControl: false,
        mapTypeControl: false,
        scaleControl: false,
        mapTypeId: google.maps.MapTypeId.ROADMAP
      });
      var infoWindow = new google.maps.InfoWindow;
      var bounds = new google.maps.LatLngBounds();

      //phpsqlajax-xmlgenerator.php, get the data from database
      downloadUrl("phpsqlajax-xmlgenerator.php", function(data) {
        var xml = data.responseXML;
        var markers = xml.documentElement.getElementsByTagName("marker");
        for (var i = 0; i < markers.length; i++) {
          var name = markers[i].getAttribute("name");
          var address = markers[i].getAttribute("address");
          var type = markers[i].getAttribute("type");
          var point = new google.maps.LatLng(
              parseFloat(markers[i].getAttribute("lat")),
              parseFloat(markers[i].getAttribute("lng")));
          var html = "<b>" + name + "</b> <br/>" + address;
          var marker = new google.maps.Marker({
            map: map,
            position: point,
            icon: icon.icon,
            animation: google.maps.Animation.BOUNCE
          });
          bindInfoWindow(marker, map, infoWindow, html);
          bounds.extend(marker.position);
        }
        map.fitBounds(bounds);
      });
    }

    function bindInfoWindow(marker, map, infoWindow, html) {
      google.maps.event.addListener(marker, 'click', function() {
        infoWindow.setContent(html);
        infoWindow.open(map, marker);
      });
    }

    function downloadUrl(url, callback) {
      var request = window.ActiveXObject ?
          new ActiveXObject('Microsoft.XMLHTTP') :
          new XMLHttpRequest;

      request.onreadystatechange = function() {
        if (request.readyState == 4) {
          request.onreadystatechange = doNothing;
          callback(request, request.status);
        }
      };

      request.open('GET', url, true);
      request.send(null);
    }

    function doNothing() {}
  </script>  

我向 downloadURL 提供了 phpsqlajax-xmlgenerator.php 文件，我用它构建了保存标记表数据的 xml 文件:

<?php
//Start xml file, create parent node
$dom = new DOMDocument("1.0");
$node = $dom->createElement("markers");
$parnode = $dom->appendChild($node);

// Opens a connection to a MySQL server
$conn = mysqli_connect('localhost', 'root', 'password', 'database');
if (mysqli_connect_errno()) {
    printf("Connect failed: %s\n", mysqli_connect_error());
    exit();
}

//Select rows in the markers table
$query = "
        SELECT * FROM `markers` WHERE 1;
";
$result = mysqli_query($conn, $query);

header("Content-type: text/xml");

// Iterate through the rows
while ($row = mysqli_fetch_assoc($result)){
  // ADD TO XML DOCUMENT NODE
  $node = $dom->createElement("marker");
  $newnode = $parnode->appendChild($node);
  $newnode->setAttribute("name",$row['name']);
  $newnode->setAttribute("address", $row['address']);
  $newnode->setAttribute("lat", $row['lat']);
  $newnode->setAttribute("lng", $row['lng']);
  $newnode->setAttribute("type", $row['type']);
}
echo $dom->saveXML();
?>  

到目前为止，一切都运行良好，只要数据库中只有一个画廊， map 和标记都是正确的。
现在我的问题来了:我需要一种方法来向 phpsqlajax-xmlgenerator.php 提供 gallery_id，以便执行正确的查询，因为旧查询只返回每一行标记，无论画廊如何。我想将 phpsqlajax-xmlgenerator.php 代码放在 gallery.php 页面的顶部并直接在页面上生成 xml 文件，但是我应该向 downloadURL 函数提供什么？画廊.php？我考虑的另一种方法是将某种 $_GET 请求放入 downloadURL 参数中，但我找不到正确执行该操作的方法。

Answer 1

将 gallery_id 与 URL 一起传递，例如:

downloadUrl("phpsqlajax-xmlgenerator.php?id=3", function(data) {

并根据get-parameter构建sql:

$id=@intval($_GET['id']);
if($id<1){
  exit();
}
$query = 'SELECT * FROM `markers` WHERE gallery_id='.$id;