Added near by search support

[gagan-bansal]

I have added near by search support. It works based on geohash concept. Redis also uses same concept for near search.

Query syntax:

GET /cities?near=lat,lon&distance=meters

There is no index created in json-server at run time for near search query.
On latitude and longitude property of data geohash is calculated and stored along data. The geohash is used for nearby search. I have used node-geohash and geo-nearby modules to achieve the same.

Sample output

{
  "id": 1,
  "city": "Jeogiwe",
  "lat": -28.12785,
  "lon": -145.96895,
  "geohash": 344516337195371
}

To generate the sample random location data use following script

var dream = require('dreamjs')
var hash = require('ngeohash')
var jsonfile = require('jsonfile')
dream.customType('incrementalId', function(helper){
      return helper.previousItem ? helper.previousItem.id+1 : 1;
})
var data = dream
.schema({
  id: 'incrementalId',
  city: 'city',
  lat: 'latitude',
  lon: 'longitude'
})
.generateRnd(10000)
.output()

data.forEach(function(city) {
  city.geohash = hash.encode_int(city.lat, city.lon);
})
jsonfile.writeFileSync('random-locations.json', {cities: data}, {spaces: 2});

One doubt from my side, I have added default latitude, longitude and geohash property name in src/server/router/index.js but there should be a better place to add default and overwrite these properties while creating an instance of json-server when used as module. At command line i have added option to override the default property.

[gagan-bansal]

@typicode any feedback on this?

[typicode]

Hi @gagan-bansal,

Sorry about that. Thank you for the very good PR.
I'm a little busy right now with hotel but I'll check this as soon as I can.

[gagan-bansal]

@typicode thanks, that is fine.

[gagan-bansal]

@typicode I saw this today my old pull request.
Is it helpful now, should I look into this again to resolve the conflicts?

If you think this feature is useful I can look again.
Thanks