如何在2.1 MongoDB C#驱动程序中使用地理空间查询? [英] How do I use a geospatial query in the 2.1 MongoDB C# driver?
问题描述
我已经为此努力了好几天.我有一个非常简单的查询，试图在C#中运行，它在外壳中看起来像这样.
I've been banging my head on this one for days. I have a very simple query I'm trying to run in C#, it looks like this in the shell.
db.runCommand({geoNear: "items", near: {type: "Point", coordinates : [-111.283344899999, 47.4941836]}, spherical : true, distanceMultiplier: 3963.2, maxDistance : 25});
我的收藏看起来像这样
{
"_id" : ObjectId(),
"Title" : "arst",
"Description" : "<p>arst</p>",
"Date" : new Date("11/29/2015 09:28:15"),
"Location" : {
"type" : "Point",
"Coordinates" : [-111.28334489999998, 47.4941836]
},
"Zip" : "59405"
}
根据此处的文档 MongoDB C#API文档 MongoDB. Driver.Builders.Query对象现在是旧版.所以当我做这样的事情
According to the docs here MongoDB C# API Docs the MongoDB.Driver.Builders.Query object is now legacy. So when I do something like this
var point = new GeoJson2DGeographicCoordinates(double.Parse(longitude), double.Parse(latitude)) ;
var query = Query<Item>.Near(x => x.Location, new GeoJsonPoint<GeoJson2DGeographicCoordinates>(point), distance, true);
var result = collection.Find(query);
编译器抱怨无法将其从IMongoQuery转换为FilterDefinition.这告诉我，新的2.1库不支持旧版Query<>构建器.但是对于我一生，我无法在引用替代文件的api文档中找到任何地方?
The compiler complains that it can't convert from IMongoQuery to FilterDefinition. This tells me that the legacy Query<> builder isn't supported by the new 2.1 library. But for the life of me I can't find anywhere in the api docs that reference a replacement?
有人可以在2.1 C#驱动程序中执行此简单的地理空间查询时指出正确的方向吗?我很困惑.
Can anyone point me in the right direction on executing this simple geo-spatial query in the 2.1 C# Driver? I'm stumped.
此外，如果没有，shell命令将无法在集合上创建2dsphere索引.这是索引输出.
Also, I do have a 2dsphere index created on the collection, if I didn't the shell command wouldn't work. Here's the index output.
{
"v" : 1,
"key" : {
"Location.Coordinates" : "2dsphere"
},
"name" : "Location.Coordinates_2dsphere",
"ns" : "ppn.items",
"2dsphereIndexVersion" : 2
}
编辑
仔细阅读大量文档后，我想我找到了它.所有示例仍显示旧的Query<>方法，但是新方法似乎是Builders<>.Filter命名空间的一部分.所以这个代码块似乎对我有用，
After digging through a TON of documentation I think I found it. All the examples still show the legacy Query<> method, but it seems that the new method is part of the Builders<>.Filter namespace. So this code block seems to be working for me,
double lng = double.Parse(longitude);
double lat = double.Parse(latitude);
point = new GeoJson2DGeographicCoordinates(lng, lat);
pnt = new GeoJsonPoint<GeoJson2DGeographicCoordinates>(point);
dis = distance * 1609.34;
fil = Builders<Item>.Filter.NearSphere(p => p.Location.Coordinates, pnt, dis);
filter = filter & fil;
var sort = Builders<Item>.Sort.Descending("Date");
// This is the actual query execution
List<Item> items = collection.Find(filter).Sort(sort).ToListAsync().Result;
此代码块非常混乱，它是一遍又一遍的尝试和失败的结果.我敢肯定，我会想办法清理它.对于我来说，似乎有些冗长，您必须根据GeoJson2DGeographicCoordinates创建一个GeoJsonPoint，但是我敢肯定有充分的理由.如果有人知道，请随时发表评论.任何有关改进此答案的建议都非常受欢迎，这是对文档的无聊探索，因此希望这可以帮助其他人指明正确的方向.
This code block is very messy, it's the result of try and fail over and over. I'm sure I'll figure out ways to clean it up. It seems a little verbose to me that you have to create a GeoJsonPoint from a GeoJson2DGeographicCoordinates, but I'm sure there's a good reason for it. If anyone knows, please feel free to comment. Any suggestions on improving this answer are very welcome, this has been a frustrating dig through documentation, so hopefully this helps point someone else in the right direction.
推荐答案
这是我要这样做的方式:
this is how I do it on my end:
public IQueryable<TEntity> FindNear<TEntity>(string collectionName, Expression<Func<TEntity, object>> field, double longitude, double latitude, double maxDistanceInKm) where TEntity : IEntity
{
var collection = database.GetCollection<TEntity>(collectionName);
var point = GeoJson.Point(GeoJson.Geographic(longitude, latitude));
var filter = Builders<TEntity>.Filter.Near(field, point, maxDistanceInKm * 1000);
return collection.Find(filter).ToList().AsQueryable();
}
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