How can I find nearby place with latitude and long

问题:

Am very new to mongodb and golang. I have a collection named "myplace" It has the following fileds place_name, city, latitude, longitude. My question is user in some place and searching the nearby places. How can I query to mongodb to find near by locations. Also in golang.

My doc structure

{
    "_id" : ObjectId("544a2147785b707b340ed6c7"),
    "latitude" : 12.36547,
    "longitude" : 1.235689,
    "place_name" : "some_place",
    "city" : "Some city"
}

Thanks in advance

回答1:

Hi For your case I think you should changed above doc as below

    {
    "_id" : ObjectId("545749dba2b0b4cf603a7546"),
    "city" : "B",
    "placeName" : "A",
    "loc" : {
        "lon" : 51.10682735591432,
        "lat" : -114.11773681640625
    }
}
{
    "_id" : ObjectId("545749f3a2b0b4cf603a7547"),
    "city" : "B1",
    "placeName" : "A1",
    "loc" : {
        "lon" : 51.09144802136697,
        "lat" : -114.11773681640625
    }
}

After that indexing the above documents as below

db.collectionName.ensureIndex({loc:"2d"})

If indexing executing properly then write following query to find out near by documents

db.location.find({loc: {$near:[51,-114]}})

for more help you should refer this mongo $near and $geoNear click here

and sorry for golang because I don't know more about golang

for golang

var places []Place
lat := 51.515614
long := -0.268998
err = coll.Find(bson.M{"loc": bson.M{"$near": []float64{long, lat}, "$maxDistance" :      0.056}}).All(&places)

回答2:

This link might help you https://github.com/mendrugory/Airports

MongoDB query (python)

def get_closest_airports(lonlat, limit=10):
    """
    Using a raw query it returns the "limit" closest airports.

    :param latlon list:
    :return list of airports:
    """
    return Airport.objects(
        __raw__={"loc": {"$near": {"$geometry": {"type": "Point", "coordinates": lonlat}}}}).limit(limit)

json structure is as following

{"city": "Goroka", "tz": "Pacific/Port_Moresby", "name": "Goroka", "dst": "U", "loc": {"type": "Point", "coordinates": [145.391881, -6.081689]}, "country": "Papua New Guinea", "iata/faa": "GKA", "altitude": 5282.0, "icao": "AYGA", "timezone": 10.0, "id": 1}