MongoDB geospatial index in C#
I have been trying to get started but run into the same rock time after time trying to create and query MongoDB with C# official driver. The problem is how to create data with geo information. I am just not finding the answer.
Code:
MongoUrl url = new MongoUrl("mongodb://xxx.xx.x.xx/mydb");
MongoServer server = MongoServer.Create(url);
MongoDatabase database = server.GetDatabase("mydb");
<-- this works fine
BsonDocument[] batch = {
new BsonDocument {
{ "name", "Bran" },
{ "loc", "10, 10" }
},
new BsonDocument {
{ "name", "Ayla" },
{ "loc", "0, 0" }
}
};
places.InsertBatch(batch);
<-- that part is wrong somehow
places.EnsureIndex(IndexKeys.GeoSpatial("loca"));
var queryplaces = Query.WithinCircle("loca", 0, 0, 11);
var cursor = places.Find(queryplaces);
foreach (var hit in cursor)
{
foreach (var VARIABLE in hit)
{
Console.WriteLine(VARIABLE.Value);
}
}
<-- I think that part should show both documents, now showing none. A s开发者_如何学JAVAimple find shows them both. Would be happy for some help.
example below is in C# (it's important to note order in the array which is longitude, latitude- follows the more logical order of x,y as opposed to the more commonly used form where latitude precedes longitude) :
1.) first your class needs to have this:
public double[] Location { get; set; }
public double Latitude
{
get { return _latitude; }
set
{
Location[1] = value;
_latitude = value;
}
}
public double Longitude
{
get { return _longitude; }
set
{
Location[0] = value;
_longitude = value;
}
}
public MyClass()
{
Location = new double[2];
}
2.) then here is some code to get you started with the official C# driver and doing an insert w/ use of geo indexing:
/// <summary>
/// Inserts object and creates GeoIndex on collection (assumes TDocument is a class
/// containing an array double[] Location where [0] is the x value (as longitude)
/// and [1] is the y value (as latitude) - this order is important for spherical queries.
///
/// Collection name is assigned as typeof(TDocument).ToString()
/// </summary>
/// <param name="dbName">Your target database</param>
/// <param name="data">The object you're storing</param>
/// <param name="geoIndexName">The name of the location based array on which to create the geoIndex</param>
/// <param name="indexNames">optional: a dictionary containing any additional fields on which you would like to create an index
/// where the key is the name of the field on which you would like to create your index and the value should be either SortDirection.Ascending
/// or SortDirection.Descending. NOTE: this should not include geo indexes! </param>
/// <returns>void</returns>
public static void MongoGeoInsert<TDocument>(string dbName, TDocument data, string geoIndexName, Dictionary<string, SortDirection> indexNames = null)
{
Connection connection = new Connection(dbName);
MongoCollection collection = connection.GetMongoCollection<TDocument>(typeof(TDocument).Name, connection.Db);
collection.Insert<TDocument>(data);
/* NOTE: Latitude and Longitude MUST be wrapped in separate class or array */
IndexKeysBuilder keys = IndexKeys.GeoSpatial(geoIndexName);
IndexOptionsBuilder options = new IndexOptionsBuilder();
options.SetName("idx_" + typeof(TDocument).Name);
// since the default GeoSpatial range is -180 to 180, we don't need to set anything here, but if
// we wanted to use something other than latitude/longitude, we could do so like this:
// options.SetGeoSpatialRange(-180.0, 180.0);
if (indexNames != null)
{
foreach (var indexName in indexNames)
{
if (indexName.Value == SortDirection.Decending)
{
keys = keys.Descending(indexName.Key);
}
else if (indexName.Value == SortDirection.Ascending)
{
keys = keys.Ascending(indexName.Key);
}
}
}
collection.EnsureIndex(keys, options);
connection.Db.Server.Disconnect();
}
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using MongoDB.Bson;
using MongoDB.Driver;
namespace MyMongo.Helpers
{
public class Connection
{
private const string DbName = "";
private const string Prefix = "mongodb://";
//private const string Server = "(...):27017/";
private const string Server = "localhost:27017/";
private const string PassWord = "";
private const string UserName = "";
private const string Delimeter = "";
//if using MongoHQ
//private const string Delimeter = ":";
//private const string Prefix = "mongodb://";
//private const string DbName = "(...)";
//private const string UserName = "(...)";
//private const string Server = "@flame.mongohq.com:(<port #>)/";
//private const string PassWord = "(...)";
private readonly string _connectionString = string.Empty;
public MongoDatabase Db { get; private set; }
public MongoCollection Collection { get; private set; }
public Connection()
{
_connectionString = Prefix + UserName + Delimeter + PassWord + Server + DbName;
}
public Connection(string dbName)
{
_connectionString = Prefix + UserName + Delimeter + PassWord + Server + DbName;
Db = GetDatabase(dbName);
}
//mongodb://[username:password@]hostname[:port][/[database][?options]]
public MongoDatabase GetDatabase(string dbName)
{
MongoServer server = MongoServer.Create(_connectionString);
MongoDatabase database = server.GetDatabase(dbName);
return database;
}
public MongoCollection<TDocument> GetMongoCollection<TDocument>(string collectionName, MongoDatabase db, SafeMode safeMode = null)
{
if (safeMode == null) { safeMode = new SafeMode(true); }
MongoCollection<TDocument> result = db.GetCollection<TDocument>(collectionName, safeMode);
return result;
}
}
}
After looking and searching I found the answer here: https://github.com/karlseguin/pots-importer/blob/master/PotsImporter/NodeImporter.cs
This to be read with my first piece of code as this fixes it.
MongoCollection<BsonDocument> places =
database.GetCollection<BsonDocument>("places");
BsonDocument[] batch = {
new BsonDocument { { "name", "Bran" }, { "loc", new BsonArray(new[] { 10, 10 }) } },
new BsonDocument { { "name", "Ayla" }, { "loc", new BsonArray(new[] { 0, 0 }) } }
};
places.InsertBatch(batch);
places.EnsureIndex(IndexKeys.GeoSpatial("loc"));
var queryplaces = Query.WithinCircle("loc", 5, 5, 10);
var cursor = places.Find(queryplaces);
foreach (var hit in cursor)
{
Console.WriteLine("in circle");
foreach (var VARIABLE in hit)
{
Console.WriteLine(VARIABLE.Value);
}
}
As a point of clarification: The problem with the code in the question is that location information should not be stored as a string, but rather as an array of 2 elements (x, y).
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