javascript - Meteor 和 MongoDB 地理空间 - 边界 - $within

Question

在我的 Meteor 客户端中，我定义了一个 map 对象:

Meteor.startup(function () {
  map = L.map('map_canvas').locate({setView: true, maxZoom: 21});
  L.tileLayer('http://{s}.tile.osm.org/{z}/{x}/{y}.png', {
      attribution: '&copy; <a href="http://osm.org/copyright">OpenStreetMap</a> contributors'
  }).addTo(map);
});

我将它用作全局，这样我可以在 Template.xxxx.events、Template.yyy.rendered... 中访问它(不知道这是否是最好的方法请您提供意见)

所以到这里为止一切都很好。

现在我需要执行地理空间查询，这只能在服务器端完成:

Meteor.startup(function () {
  Meteor.publish("AllMessages", function() {
    lists._ensureIndex( { location : "2d" } );
    var bottomLeftLat = map.getBounds()._southWest.lat;
    var bottomLeftLng = map.getBounds()._southWest.lng;
    var topRightLat = map.getBounds()._northEast.lat;
    var topRightLng = map.getBounds()._northEast.lng;
    return lists.find( { "location": { "$within": { "$box": [ [bottomLeftLng, bottomLeftLat] , [topRightLng, topRightLat] ] } } } );
  });
});

但是我的应用程序崩溃了，我得到:

Exception from sub ZeJzWHdF8xQg57QtF ReferenceError: map is not defined
    at null._handler (app/server/Server.js:4:25)
    at _.extend._runHandler (app/packages/livedata/livedata_server.js:815:31)
    at _.extend._startSubscription (app/packages/livedata/livedata_server.js:714:9)
    at _.extend.protocol_handlers.sub (app/packages/livedata/livedata_server.js:520:12)
    at _.extend.processMessage.processNext (app/packages/livedata/livedata_server.js:484:43)

这是加载时间的问题吗？我需要设置超时并等到 map 加载后再执行查询？

编辑这是我尝试过的方法，但不起作用

服务器

Meteor.startup(function () {
  Meteor.publish("AllMessages", function() {
    lists._ensureIndex( { location : "2d" } );
    return lists.find();
  });
});

Meteor.methods({
  getListsWithinBounds: function(bounds) {
    return lists.find( { "location": { "$within": { "$box": [ [bottomLeftLng, bottomLeftLat] , [topRightLng, topRightLat] ] } } } );
  }
});

客户端

Meteor.startup(function () {
  map = L.map('map_canvas').locate({setView: true, maxZoom: 21});
  L.tileLayer('http://{s}.tile.osm.org/{z}/{x}/{y}.png', {
      attribution: '&copy; <a href="http://osm.org/copyright">OpenStreetMap</a> contributors'
  }).addTo(map);
    bounds = {};    
    map.on('locationfound', function(e){ 
      bounds.bottomLeftLat = map.getBounds()._southWest.lat;
      bounds.bottomLeftLng = map.getBounds()._southWest.lng;
      bounds.topRightLat = map.getBounds()._northEast.lat;
      bounds.topRightLng = map.getBounds()._northEast.lng;
      console.log(bounds);
      Meteor.call("getListsWithinBounds", bounds, function(err, result) {
        console.log('call'+result); // should log a LocalCursor pointing to the relevant lists
      });
    });
});

Answer 1

编辑:更好的是，使用自定义响应式(Reactive)数据源。我写了一个小教程here .

旧帖子:

我已经实现了类似的东西。在我的服务器代码中，我有以下发布功能:

// Publish those trails within the bounds of the map view.
Meteor.publish('trails', function(bounds){
 if (bounds && bounds.southWest && bounds.northEast) {
  return Trails.find({'coordinates': {'$within' : 
    { '$box' : [bounds.southWest, bounds.northEast] }
  }}, {
    limit: 100
  });
 }
});

在我的客户端代码中，我保留了仅客户端的 map 边界集合。 (基本上，它是一种只有一个文档的响应式(Reactive)模型)。

MapBounds = new Meteor.Collection(null);

我在客户端上有一个订阅，如下所示:

// Get trails that are located within our map bounds. 
Meteor.autorun(function () {
 Session.set('loading', true);
  Meteor.subscribe('trails', MapBounds.findOne(), function(){
   Session.set('loading', false);
  }); 
});

最后，我的传单类会在 map 边界发生变化时更新边界模型。

 onViewChange: function(e){
  var bounds = this.map.getBounds()
    , boundObject = { 
        southWest: [bounds._southWest.lat, bounds._southWest.lng],
        northEast: [bounds._northEast.lat, bounds._northEast.lng] 
      };

  if (MapBounds.find().count() < 1) MapBounds.insert(boundObject);
  else MapBounds.update({}, boundObject);
 }