mongodb - Geonear 不工作 - mongodb？

Question

我在集合 offers 中有以下示例 mongodb 文档。

集合:优惠

 {
   "countryCode" : "LU",
   "geoLocation" : [ 
         {
            "lat" : 49.8914114000000026,
            "lng" : 6.0950994999999999
         }
    ]
 },
 {
   "countryCode" : "DE",
   "geoLocation" : [ 
         {
            "lat" : 50.8218536999999984,
            "lng" : 9.0202151000000015
         }
    ]
 }

要求:

根据半径50公里左右的地理位置获取文档

我尝试过的:

db.getCollection('offers').aggregate([
    {
        $geoNear: {
            near: [6.0950994999999999, 49.8914114000000026],
            distanceField: "geoLocation",
            maxDistance: 50000, //50 km radius
        }
    }
]);

问题:

它正在获取所有文档，而不是搜索大约 50 公里。

任何建议将不胜感激。

Answer 1

旧版坐标对不返回以米为单位的距离，而是以弧度为单位。因此，您的 maxDistance 远大于 50km。参见 Calculate Distances with Spherical Geometry

但也要考虑这里使用的实际距离:

db.getCollection('offers').aggregate([
    {
        $geoNear: {
            near: [6.0950994999999999, 49.8914114000000026],
            distanceField: "distance"
    }
]);

返回:

{
    "_id" : ObjectId("55dc0f4b6f07ad5d3ec3b6d0"),
    "countryCode" : "DE",
    "geoLocation" : [
            {
                    "lat" : 50.8218537,
                    "lng" : 9.020215100000001
            }
    ],
    "distance" : 60.588259822017925
}
{
    "_id" : ObjectId("55dc0f4b6f07ad5d3ec3b6cf"),
    "countryCode" : "LU",
    "geoLocation" : [
            {
                    "lat" : 49.8914114,
                    "lng" : 6.0950995
            }
    ],
    "distance" : 61.93733827090219
}

因为“distanceField”是报告距查询点的投影距离的字段。

因此，起点是您的文档对于地理空间查询无效。像这样修复它们:

首先删除所有索引:

db.offers.dropIndexes();

然后修复字段:

var bulk = db.offers.initializeOrderedBulkOp(),
    count = 0;

db.offers.find({}).forEach(function(doc) { 
  //printjson(doc);

  var tmp = {
    "type": "Point",
    "coordinates": [doc.geoLocation[0].lng,doc.geoLocation[0].lat]
  };
  doc.geoLocation = tmp;
  printjson(doc);

  bulk.find({ "_id": doc._id }).updateOne({
    "$set": { "geoLocation": doc.geoLocation }
  });
  count++;

  if ( count % 1000 == 0 ) {
    bulk.execute();
    bulk = db.offers.initializeOrderedBulkOp();
  }
});

现在数据以正确的 GeoJSON 格式表示:

{
    "_id" : ObjectId("55dc14856f07ad5d3ec3b6d1"),
    "countryCode" : "LU",
    "geoLocation" : {
            "type" : "Point",
            "coordinates" : [
                    6.0950995,
                    49.8914114
            ]
    }
}
{
    "_id" : ObjectId("55dc14856f07ad5d3ec3b6d2"),
    "countryCode" : "DE",
    "geoLocation" : {
            "type" : "Point",
            "coordinates" : [
                    9.020215100000001,
                    50.8218537
            ]
    }
}

现在创建一个 2dsphere 索引:

db.offers.createIndex({ "geoLocation": "2dsphere" })

现在您可以查询了:

db.offers.aggregate([
    { "$geoNear": {
      "near": {
        "type": "Point",
        "coordinates": [6.0950994999999999, 49.8914114000000026]
      },
      "distanceField": "distance",
      "spherical": true,
      "maxDistance": 50000
    }}
])

它返回一个“近”的文档，或者实际上是 0 距离:

{
    "_id" : ObjectId("55dc14856f07ad5d3ec3b6d1"),
    "countryCode" : "LU",
    "geoLocation" : {
            "type" : "Point",
            "coordinates" : [
                    6.0950995,
                    49.8914114
            ]
    },
    "distance" : 0
}