Question

I was wondering if there are any examples that consist on basic geolocation input and database retrieval of given inputs within a certain area, preferably the user’s current location.

Answer 1

Here’s a quick overview of geospatial queries in MongoDB:

1. You have to insert location information in your collection via 2D array

   db.example.insert( {"location": [x,y], "category": "restaurant"})
   

2. Set up a geospatial indexes on the collection by indicating the location field with “2d” option.

   db.example.ensureIndex( { "location" : "2d" } )
   

   Now the collection will have an index which all geospatial queries will be done against.

3. To query for locations nearby a point (i.e. the user’s current location), use the find() command with $near operand on the location field giving the point coordinates (i.e. 100, 100.)

   db.example.find( { "location": { $near : [100, 100] } } )
   

4. To find users current location, you would need higher level application support to get the user’s current information.

For more information:

• MongoDB documentation:
  http://www.mongodb.org/display/DOCS/Geospatial+Indexing

• The $near operator: http://docs.mongodb.org/manual/reference/operators/#_S_near