C#用弹性搜索计算地理距离（nest 2）

Question

我正在实现一个能够接收 10 个最近对象的程序。作为数据库，我使用 ElasticSearch，我的模型如下所示。

[Nest.ElasticsearchType(Name = "eventelastic", IdProperty = "Id")]
public class EventElastic:BaseElastic
{
    [Nest.String]
    public string EventName { get; set; }
    [Nest.Date]
    public DateTime CreateTime { get; set; }
    [Nest.String]
    public string Country { get; set; }
    [Nest.String]
    public string City { get; set; }
    [Nest.String]
    public string Place { get; set; }
    [Nest.Boolean]
    public bool IsPrivate { get; set; }
    [Nest.Boolean]
    public bool IsSponsored { get; set; }
    [Nest.String]
    public string ImageWeb { get; set; }
    [Nest.Number]
    public int MaxPersons { get; set; }
    [Nest.GeoPoint]
    public LocationModel Location { get; set; }


}

[Nest.ElasticsearchType(Name = "location", IdProperty = "Id")]
public class LocationModel
{
    public LocationModel(double lon, double lat)
    {
        Lon = lon;
        Lat = lat;
    }

    public double Lon { get; set; }

    public double Lat { get; set; }
}

我创建了一个这样的索引

connection.CreateIndex("index", s => s.Mappings(f => f.Map<EventElastic>(m => m.AutoMap().Properties(p=> p.GeoPoint(g => g.Name(n => n.Location))))));

然后我像这样插入新文档

var response = connection.IndexAsync<EventElastic>(model, idx => idx.Index("index"));
            response.ContinueWith(t =>
            {
                if (!t.Result.IsValid)
                {
                    log.Error(t.Result.ServerError.Error.Reason);
                }
            });

模型的所有值都已设置，并且可以正常工作。

但现在我想在 10 公里范围内获取最近的 10 个。我这样查询

var geoResult = connection.Search<EventElastic>(s => s.From(0).Size(10)
            .Query(query => query.Bool(b => b.Filter(filter => filter
                    .GeoDistance(geo => geo
                        .Field(f => f.Location) //<- this 
                        .Distance("10km").Location(lon, lat)
                        .DistanceType(GeoDistanceType.SloppyArc)
                        ))
                )
            )
        );

但它没有 return 任何文档，但如果我将距离值设置为 10000km，它 return 是一个文档。

我在模型中使用的数据是：拉特：47.4595248 经度：9.6385962

我在搜索中使用的位置：拉特：47.4640298 伦敦：9.6389685

那些地方相距100米。有人可以帮我找出代码中的错误吗？是否可以从elasticsearch服务器获取计算的距离？

顺便说一句：我正在设置默认索引

var settings = new ConnectionSettings(pool).DefaultIndex("index");

编辑我发现了错误：

var geoResult = connection.Search<EventElastic>(s => s.From(0).Size(10)
        .Query(query => query.Bool(b => b.Filter(filter => filter
                .GeoDistance(geo => geo
                    .Field(f => f.Location) 
                    .Distance("10km").Location(lat, lon) //wrong parameter
                    .DistanceType(GeoDistanceType.SloppyArc)
                    ))
            )
        )
    );

我不得不改变纬度和经度的位置。

但是我没有得到计算的距离，有人知道我怎样才能得到距离吗？

此致

Answer 1

您可以将 Distance 添加到您的文档中，并在您的查询中使用 sctipt fields 来更新此值。

var geoResult = client.Search<EventElastic>(s => s.From(0).Size(10)
    .ScriptFields(sf => sf
        .ScriptField("distance", descriptor => descriptor
            .Inline("doc[\u0027location\u0027].distanceInKm(lat,lon)")
            .Lang("groovy")
            .Params(f => f.Add("lat", lat).Add("lon", lon))))
    .Query(query => query.Bool(b => b.Filter(filter => filter
        .GeoDistance(geo => geo
            .Field(f => f.Location)
            .Distance("10km").Location(lat, lon)
            .DistanceType(GeoDistanceType.SloppyArc)
        ))
        )
    )
    .Sort(sort => sort
        .GeoDistance(g => g
            .Field(f => f.Location)
            .Order(SortOrder.Ascending)
            .PinTo(new GeoLocation(1.5, 1))
            .DistanceType(GeoDistanceType.SloppyArc)))
    );


public class EventElastic
{
    ..
    public double Distance {get;set;}
}

elasticsearch 的响应：

{
   "took": 3,
   "timed_out": false,
   "_shards": {
      "total": 5,
      "successful": 5,
      "failed": 0
   },
   "hits": {
      "total": 2,
      "max_score": null,
      "hits": [
         {
            "_index": "my_index",
            "_type": "data",
            "_id": "1",
            "_score": null,
            "fields": {
               "distance": [
                  55.65975203179589
               ]
            },
            "sort": [
               55659.66677843493
            ]
         },
         {
            "_index": "my_index",
            "_type": "data",
            "_id": "2",
            "_score": null,
            "fields": {
               "distance": [
                  124.45896068602408
               ]
            },
            "sort": [
               124411.81715215484
            ]
         }
      ]
   }
}

希望对您有所帮助。

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