Very early proof of concept golang implementation of the GOV.UK Imminence API

places_of_interest.go

package main

import (
	"encoding/json"
	"fmt"
	"labix.org/v2/mgo"
	"labix.org/v2/mgo/bson"
	"net/http"
)

type Point struct {
	Longitude float64
	Latitude  float64
}

// TODO: Implement correct JSON field names for serialization
type Place struct {
	ServiceSlug     string `bson:"service_slug"`
	DataSet_version int    `bson:"data_set_version"`
	Name            string `bson:"name"`
	SourceAddress   string `bson:"source_address"`
	Address1        string `bson:"address1"`
	Address2        string `bson:"address2"`
	Town            string `bson:"town"`
	Postcode        string `bson:"postcode"`
	AccessNotes     string `bson:"access_notes"`
	GeneralNotes    string `bson:"general_notes"`
	Url             string `bson:"url"`
	Email           string `bson:"email"`
	Phone           string `bson:"phone"`
	Fax             string `bson:"fax"`
	TextPhone       string `bson:"text_phone"`
	// Location        Point
}

func buildPlacesQuery(service string, version int, loc Point) bson.M {
	return bson.M{
		"service_slug":     service,
		"data_set_version": version,
		"location": bson.M{
			"$near": []float64{loc.Longitude, loc.Latitude},
			"$maxDistance": 1000,
		},
	}
}

// TODO: extract from URL: service, version, prefered location, number of results
// TODO: implement maximum distance / number of results
func findPlaces(resp http.ResponseWriter, req *http.Request) {
	service := "register-offices"
	version := 2
	location := Point{0, 0}

	session := getMgoSession()
	db := session.DB("imminence_development")
	query := buildPlacesQuery(service, version, location)

	var results []Place
	err := db.C("places").Find(query).All(&results)
	if err != nil {
		http.Error(resp, err.Error(), http.StatusInternalServerError)
	}

	b, err := json.Marshal(results)
	if err != nil {
		http.Error(resp, err.Error(), http.StatusInternalServerError)
	}

	fmt.Fprintf(resp, string(b))
}

func Log(handler http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		fmt.Printf("%s %s %s\n", r.RemoteAddr, r.Method, r.URL)
		handler.ServeHTTP(w, r)
	})
}

var (
	mgoSession *mgo.Session
)

func getMgoSession() *mgo.Session {
	if mgoSession == nil {
		var err error
		mgoSession, err = mgo.Dial("localhost")
		mgoSession.SetMode(mgo.Monotonic, true)

		if err != nil {
			panic(err)
		}
	}
	return mgoSession.Clone()
}

func main() {
	http.HandleFunc("/places/", findPlaces)
	http.ListenAndServe(":9090", Log(http.DefaultServeMux))
}