<script src="https://cdn.rawgit.com/google/code-prettify/master/loader/run_prettify.js"></script>

MongoDB simple CRUD example in Go

Overview

This is a quick CRUD example that I put together for the purpose of having a easy reference for MGO. It uses Go's version of OOP to:

1. Create an intial connection, that can be defer closed in the main function.
2. Copy the session across each object method, use it and defer close it in the method.

Example

package main

import (
	"fmt"
	"log"
	"time"

	"gopkg.in/mgo.v2"
	"gopkg.in/mgo.v2/bson"
)

// Person
type Person struct {
	Name  string `bson:"name" json:"name"`
	Phone string `bson:"phone" json:"phone"`
}

// MySession allows for shared connections
type MySession struct {
	mainSession *mgo.Session
}

func (s *MySession) CreateNewRecord(p Person) {
	fmt.Println("Creating new record")

	// Copy & defer close the main session here
	session := s.mainSession.Copy()
	defer session.Close()

	conn := session.DB("MYDB").C("CRUD")
	err := conn.Insert(p)
	if err != nil {
		log.Fatal(err)
	}
}

func (s *MySession) ReadRecord() {
	fmt.Println("Reading new record")

	// Copy & defer close the main session here
	session := s.mainSession.Copy()
	defer session.Close()

	conn := session.DB("MYDB").C("CRUD")

	result := Person{}
	err := conn.Find(bson.M{"name": "Eric"}).One(&result)
	if err != nil {
		log.Fatal(err)
	}
	log.Printf("%+v\n", result)
}

func (s *MySession) UpdateRecord(p Person) {
	fmt.Println("Updating record")

	// Copy & defer close the main session here
	session := s.mainSession.Copy()
	defer session.Close()

	p.Name = "New Name"
	conn := session.DB("MYDB").C("CRUD")

	err := conn.Update(bson.M{"name": "Eric"}, bson.M{"$set": p})
	if err != nil {
		log.Fatal(err)
	}
}

func (s *MySession) DeleteRecord(p Person) {
	fmt.Println("Deleting new record")

	// Copy & defer close the main session here
	session := s.mainSession.Copy()
	defer session.Close()

	conn := session.DB("MYDB").C("CRUD")

	err := conn.Remove(bson.M{"name": "New Name"})
	if err != nil {
		log.Fatal(err)
	}
}

var mainDBConn *mgo.Session

// Create initial connection to MGO here
// hand over to global var mainDBConn
// and most importantly remember to defer close the conn
// in the main function
func init() {
	ms, err := mgo.Dial(mgoURL)
	if err != nil {
		log.Fatal(err)
	}
	mainDBConn = ms
}

const (
	mgoURL = "mongodb://127.0.0.1"
)

func main() {
	//create initial connection to MGO
	defer mainDBConn.Close()
	
	// Create a new MySession object and give it the main
	// MGO conn
	mys := MySession{
		mainSession: mainDBConn,
	}

	// Create a person new object
	person1 := Person{Name: "Eric", Phone: "12345"}

	// Create the record
	mys.CreateNewRecord(person1)
	time.Sleep(5 * time.Second)

	// Read the record
	mys.ReadRecord()
	time.Sleep(5 * time.Second)

	// Update the record
	mys.UpdateRecord(person1)
	time.Sleep(5 * time.Second)

	// Delete the record
	mys.DeleteRecord(person1)
	time.Sleep(5 * time.Second)
}