golang latihan crud sederhana mongodb

readme.md

cobamgo.go

package main

import (
	"fmt"
	"github.com/globalsign/mgo"
	"github.com/globalsign/mgo/bson"
)

func FErr(err error) {
	if err != nil {
		panic(err)
	}
}
func SetupDB(url, DBNm string, isDrop bool) (close func(), DB *mgo.Database, err error) {
	var session *mgo.Session
	session, err = mgo.Dial(url)
	close = session.Close
	session.SetMode(mgo.Monotonic, true)
	DB = session.DB(DBNm)
	if isDrop {
		err = DB.DropDatabase()
	}
	return
}
func NewIds(n int) (ids []bson.ObjectId) {
	ids = make([]bson.ObjectId, n)
	for i := 0; i < n; i++ {
		ids[i] = bson.NewObjectId()
	}
	return
}
func main() {
	closeSsn, DB, err := SetupDB("localhost", "dbku", true)
	FErr(err)
	defer closeSsn()
	koleksiku := DB.C("koleksiku")
	var (
		rslt  bson.M
		rslts []bson.M
	)
	//insert data bertipe bson.M
	FErr(koleksiku.Insert(bson.M{"field1Name": "1st-field-value", "field2Name": "2nd-field-value"}))
	FErr(koleksiku.Find(nil).One(&rslt)) // find documents
	id := rslt["_id"].(bson.ObjectId)
	FErr(koleksiku.FindId(id).One(&rslt)) // find document by id
	fmt.Printf("%+v\n", rslt)
	FErr(koleksiku.Update(bson.M{"_id": id}, bson.M{"field1Name": "1st-field-value-updated", "field2Name": "2nd-field-value-updated"}))
	FErr(koleksiku.Find(nil).One(&rslt))
	fmt.Printf("%+v\n", rslt)
	FErr(koleksiku.RemoveId(id)) // delete document by id
	id = bson.NewObjectId()
	offset := id
	FErr(koleksiku.Insert(bson.M{"_id": id, "fld1": "1-v1", "fld2": "2-v1"}))
	ids := NewIds(2)
	bulk := koleksiku.Bulk()
	bulk.Insert( // bulk insert
		bson.M{"_id": ids[0], "fld1": "1-v2", "fld2": "2-v2"},
		bson.M{"_id": ids[1], "fld1": "1-v3", "fld2": "2-v3"},
	)
	_, err = bulk.Run()
	FErr(err)
	type Model1 struct {
		ID     bson.ObjectId `bson:"_id"`
		Field1 string        `bson:"fld1"`
		Field2 string        `bson:"fld2"`
	}
	id = bson.NewObjectId()
	// insert data jika bertipe struct maka harus menggunakan tag bson:
	// https://github.com/golang/go/wiki/Well-known-struct-tags#list-of-well-known-struct-tags
	// https://medium.com/golangspec/tags-in-golang-3e5db0b8ef3e
	FErr(koleksiku.Insert(Model1{id, "1-v4", "2-v4"}))
	FErr(koleksiku.Find(nil).All(&rslts)) // find all documents
	fmt.Printf("%+v\n", rslts)
	limit := 2
	rsltMdl1 := make([]Model1, limit)
	// cari docs dimana _id > offset , jumlah docs hasil sebatas limit
	// hasil tampung di var bertipe slice of Model1
	FErr(koleksiku.Find(bson.M{"_id": bson.M{"$gt": offset}}).Limit(limit).All(&rsltMdl1))
	fmt.Printf("%+v\n", rsltMdl1)
}
/*
catatan :
- istilah: table di sql jadi collection di mgo , row di sql jadi document di mgo
- tidak ada semacam CREATE DATABASE & CREATE TABLE di mgo ,
- database & collection di mgo jika belum ada / sudah di - drop akan dibuat saat pertama kali ada proses insert
- di sql kita tahu bahwa field - field harus dibuat (create table) dahulu sebelum bisa insert data ,
- tetapi di mgo , field - field dibuat bersamaan dengan value data - data - nya ketika insert
- di mgo document , field _id selalu ada dan otomatis di - index untuk pencarian
*/