Go Sample : How to do a Distinct

distinct.go

package main

import (
        "fmt"
	"log"
        "gopkg.in/mgo.v2"
        "gopkg.in/mgo.v2/bson"
)

type City struct {
        Name string
        Zip int
		State string
}

func main() {
        session, err := mgo.Dial("localhost")
        if err != nil {
                panic(err)
        }
        defer session.Close()

        session.SetMode(mgo.Monotonic, true)



        c := session.DB("demo").C("cities")
		
		err = c.DropCollection()
		
		err = c.Insert(
			&City{"Aberdeen", 57401, "SD"},
			&City{"Aberdeen", 57402, "SD"},
			&City{"Austin", 78701, "TX"},
			&City{"Austin", 78702, "TX"},
			&City{"Austin", 78703, "TX"},
			&City{"Austin", 78704, "TX"},
			&City{"Austin", 78705, "TX"},
			&City{"Anchorage", 99501, "AL"},
			&City{"Anchorage", 99521, "AL"},
			&City{"Anchorage", 99524, "AL"},
			&City{"Montpelier", 83254, "ID"},
			&City{"Springfield", 62701, "IL"},
			&City{"Springfield", 62702, "IL"},
			&City{"Springfield", 62703, "IL"},
			&City{"Springfield", 62704, "IL"},
			&City{"Indianapolis", 46201, "IN"})
			
        if err != nil {
                 log.Fatal(err)
        }
        
		// Query Distinct
		var result []string
        err = c.Find( bson.M{"name": bson.M{"$regex":"^A", "$options":"si"}}  ).Distinct("name", &result)
        if err != nil {
                log.Fatal(err)
        }

        fmt.Println( result )
}