find nearest restaurant location using mongodb and php

Question

I have a collection in MongoDB called restaurants

   {
       "_id" : ObjectId("5281f8d660ad39040c000001"),
       "name" : "Bucksters Coffee",
       "serves" : "Fast Food",
       "location" : [ 
          "23.755339", 
          "90.375408"
       ]
    }    
    {
        "_id" : ObjectId("5285cf0860ad39380b000000"),
        "name" : "A1 Donuts",
        "serves" : "Fast Food",
        "location" : [ 
            "18.5087016", 
            "73.8124984"
        ]
    }
    {
        "_id" : ObjectId("5285cf3f60ad39380b000002"),
        "name" : "B1 Donuts",
        "serves" : "Fast Food",
        "location" : [ 
            "18.4893148", 
            "73.8213213"
        ]
    }
    {
        "_id" : ObjectId("5285e7a260ad39380b000009"),
        "name" : "C1 Donuts",
        "serves" : "Fast Food",
        "location" : [ 
            "18.5308225", 
            "73.8474647"
        ]
    }

And my location is ["18.5170345","73.83476"] and I want to find nearest restaurants from my location around 5 kms.

so I try following things,

for insert restaurants,

<?php
try {

   $conn = new Mongo('localhost');

  // access database
  $db = $conn->demo;

  // access collection
  $collection = $db->restaurants;

  $forlatadd="shivaji nagar, pune";

  //for lat& Long
$prepAddr = str_replace(' ','+',$forlatadd);

$geocode=file_get_contents('http://maps.google.com/maps/api/geocode/json?address='.$prepAddr.'&sensor=false');

$output= json_decode($geocode);

$lat = $output->results[0]->geometry->location->lat;
$long = $output->results[0]->geometry->location->lng;


  $a=array("$lat","$long");
  //print_r($a);
   $document = array( "name" => "C1 Donuts","serves" => "Fast Food","location" =>$a);

  $collection->insert($document);

    $collection->ensureIndex(array("location" => "2d"));


  // disconnect from server
  $conn->close();
} catch (MongoConnectionException $e) {
  die('Error connecting to MongoDB server');
} catch (MongoException $e) {
  die('Error: ' . $e->getMessage());
}
?>

And for searching data,

<?php
try {

  $conn = new Mongo('localhost');

  // access database
  $db = $conn->demo;

  // access collection
  $collection = $db->restaurants;


  $forlatadd="deccan, pune";

  //for lat& Long
$prepAddr = str_replace(' ','+',$forlatadd);

$geocode=file_get_contents('http://maps.google.com/maps/api/geocode/json?address='.$prepAddr.'&sensor=false');

$output= json_decode($geocode);

$lat = $output->results[0]->geometry->location->lat;
$long = $output->results[0]->geometry->location->lng;

$a=array("$lat","$long");
//print_r($a);

$distance='5000';

$query = array('location' => array('$near' => array($lat,$long),'$maxDistance' => intval($distance)));


$cursor = $collection->find($query);
if ($cursor) {
    echo json_encode(iterator_to_array($cursor));
} else {
    echo "{ 'status' : 'false' }";
}

   // disconnect from server
  $conn->close();
} catch (MongoConnectionException $e) {
  die('Error connecting to MongoDB server');
} catch (MongoException $e) {
  die('Error: ' . $e->getMessage());
}
?>

But this gives following error

Error: localhost:27017: can't find any special indices: 2d (needs index), 2dsphere (needs index), for: { location: { $near: [ 18.5170345, 73.83476 ], $maxDistance: 5000 } }

But i already done

$collection->ensureIndex(array("location" => "2d"));

while inserting new restaurants in collection, Please help me to find nearest restaurants from my locations.

Answer 1

It working for me,

Only change,

$a=array("$lat","$long");  //It takes lat & long as string

to

$a=array($long,$lat);  //It takes lat&long as float.

And its working

Answer 2

In mongodb docs, they specify order in a location definition and indeed I had problems with the order in my previous dev :

Important Specify coordinates in this order: “longitude, latitude.”

http://docs.mongodb.org/manual/reference/operator/query/near/