geospatial - MongoDB 'unable to find index for $geoNear query'

Question

I'm just trying to get a simple near query working. Here's a sample of my document.

{"point": 
  {"type": "Point", 
     "coordinates": [30.443902444762696, -84.27326978424058]}, 
   "created_on": {"$date": 1398016710168}, 
   "radius": 180, 
   "user": {"$oid": "53543188eebc5c0cc416b77c"}, 
   "_id": {"$oid": "53544306eebc5c0ecac6cfba"}, 
   "expires_on": {"$date": 1399831110168}
}

and with mongod I tried the command:

db.bar.find({point: {$near: [-84.26060492426588, 30.45023887165371]}});

but I get this error:

error: { "$err" : "Unable to execute query: error processing query: ns=foo.bar skip=0 Tree: GEONEAR field=point maxdist=1.79769e+308 isNearSphere=0 || First: notFirst: full path: point Sort: {} Proj: {} planner returned error: unable to find index for $geoNear query", "code" : 17007 }

Maybe my google fu is not so sharp today but I couldn't find anything. Also, I ran the ensure index command. My intention is that these are map locations.

db.bar.ensureIndex({a:1});
db.bar.ensureIndex({geo:"2d"});

Answer 1

Few problems, you created your indexes on the foo collection of the foo database, but are querying the bar collection. You need to be on the correct collection.

Reading the document you have inserted you need to add a "2dsphere" index to support the geoJson objects. This index needs to be on the "point" element of your documents, so try

db.bar.createIndex({point:"2dsphere"});

You can then query as follows by providing a geoJson obj for the query:

db.bar.find(
   { point :
       { $near :
          {
            $geometry : {
               type : "Point" ,
               coordinates : [-84.27326978424058, 30.443902444762696] },
            $maxDistance : 1
          }
       }
    }
)