Best way to connect to MongoDB

My question is that should I connect to MongoDB in all of my handlers using goroutines and then disconnect the connection.

Or I should just connect to MongoDB when app starts and keep connection alive for a long time and use that connection in my handlers.

What is the best approach?

I would be thankful if you explain the advantages and disadvantages.

The latter is better

> Connect to MongoDB when app starts and keep connection alive for a long time and use that connection in my handlers

it prevents you from having to connect to the database when you need to interact with the database all the time and having to deal with cases where connection to the database is inconsistent, the former might lead to a lot of complexity.

Conventionally, connecting to your db should occur once (probably in your main.go file) and you can reference the connection in other parts of the project.

My approach that has proven to be quite performant.
Define an internal data package like so :

package data

import (
	"context"
	"log"
	"os"
	"time"

	"github.com/joho/godotenv"
	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
)

func MongoConnect() (*mongo.Client, error) {
	godotenv.Load(".env")
	str := os.Getenv("CONNECTION_STRING")
	client, err := mongo.NewClient(options.Client().ApplyURI(str))
	if err != nil {
		log.Fatal(err)
	}
	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()
	err = client.Connect(ctx)
	if err != nil {
		log.Fatal(err)
	}
	return client, nil
}

func ConnectToCollection(collectionName string) (*mongo.Collection, error) {
	client, err := MongoConnect()
	if err != nil {
		return nil, err
	}
	collection := client.Database("DATABASE_NAME").Collection(collectionName)
	return collection, nil
}

Once this is done, you can basically use this ConnectToCollection in every endpoint group (package) that needs it in a global variable. E.G:

package xxx

import "app_name/whatever/data"

var coll, _ = data.ConnectToCollection("xxx_collection_name")


func myFunction() {
	coll.InsertOne(...)
}