Update a Document

// Updates the first document that matches a query filter by using the Go driver
package main
import (
	"context"
	"fmt"
	"log"
	"os"
	"github.com/joho/godotenv"
	"go.mongodb.org/mongo-driver/v2/bson"
	"go.mongodb.org/mongo-driver/v2/mongo"
	"go.mongodb.org/mongo-driver/v2/mongo/options"
)
// Defines a Restaurant struct as a model for documents in the "restaurants" collection
type Restaurant struct {
	ID            bson.ObjectID `bson:"_id"`
	Name          string        `bson:"name"`
	AverageRating float64       `bson:"avg_rating,omitempty"`
}
// Create a filter struct to specify the document to update
type UpdateRestaurantFilter struct {
	ID bson.ObjectID `bson:"_id"`
}
// Defines a RestaurantUpdate struct to specify the fields to update
type RestaurantUpdate struct {
	AverageRating float64 `bson:"avg_rating"`
}
func main() {
	if err := godotenv.Load(); err != nil {
		log.Println("No .env file found")
	}
	var uri string
	if uri = os.Getenv("MONGODB_URI"); uri == "" {
		log.Fatal("You must set your 'MONGODB_URI' environment variable. See\n\t https://www.mongodb.com/docs/drivers/go/current/connect/mongoclient/#environment-variable")
	}
	client, err := mongo.Connect(options.Client().ApplyURI(uri))
	if err != nil {
		panic(err)
	}
	defer func() {
		if err = client.Disconnect(context.TODO()); err != nil {
			panic(err)
		}
	}()
	coll := client.Database("sample_restaurants").Collection("restaurants")
	id, _ := bson.ObjectIDFromHex("5eb3d668b31de5d588f4292b")
	filter := UpdateRestaurantFilter{ID: id}
	// Creates instructions to add the "avg_rating" field to documents
	update := bson.D{{"$set", RestaurantUpdate{AverageRating: 4.4}}}
	// Updates the first document that has the specified "_id" value
	result, err := coll.UpdateOne(context.TODO(), filter, update)
	if err != nil {
		panic(err)
	}
	// Prints the number of updated documents
	fmt.Printf("Documents updated: %v\n", result.ModifiedCount)
}