Video:

Implementing the AddRocket gRPC Handler

May 22, 2021

Course Instructor: Elliot Forbes

Hey Gophers! My name is Elliot and I'm the creator of TutorialEdge and I've been working with Go systems for roughly 5 years now. Feel free to reach out to me on twitter - @Elliot_F

In the last video, we made a start at implementing the first of our gRPC handler functions as well as implementing the database functions that back these handlers.

In this video, we are going to take this a step further and implement the AddRocket gRPC handler so that we can test adding a Rocket to the database as well as test our previous GetRocket handler.

Our AddRocket Handler

// AddRocket - adds a rocket to the database
func (h Handler) AddRocket(ctx context.Context, req *rkt.AddRocketRequest) (*rkt.AddRocketResponse, error) {
	log.Print("Add Rocket gRPC endpoint hit")
	newRkt, err := h.RocketService.InsertRocket(ctx, rocket.Rocket{
		ID:   req.Rocket.Id,
		Type: req.Rocket.Type,
		Name: req.Rocket.Name,
	})
	if err != nil {
		log.Print("failed to insert rocket into database")
		return &rkt.AddRocketResponse{}, err
	}
	return &rkt.AddRocketResponse{
		Rocket: &rkt.Rocket{
			Id:   newRkt.ID,
			Type: newRkt.Type,
			Name: newRkt.Name,
		},
	}, nil
}

Our DB Package Updates:


// InsertRocket - inserts a rocket into the rockets table
func (s Store) InsertRocket(rkt rocket.Rocket) (rocket.Rocket, error) {
	_, err := s.db.NamedQuery(
		`INSERT INTO rockets
		(id, name, type)
		VALUES (:id, :name, :type)`,
		rkt,
	)
	if err != nil {
		return rocket.Rocket{}, errors.New("failed to insert into database")
	}
	return rocket.Rocket{
		ID:   rkt.ID,
		Type: rkt.Type,
		Name: rkt.Name,
	}, nil
}

Testing with BloomRPC

Let’s navigate into BloomRPC and import our rocket.proto file from the Protobuf monorepo and then attempt both an AddRocket gRPC requests and then, using the ID from the AddRocket request, let’s attempt a GetRocket gRPC request.

Updating our GetRocket DB Method


// GetRocketByID - retrieves a rocket from the database by id
func (s Store) GetRocketByID(id string) (rocket.Rocket, error) {
	var rkt rocket.Rocket
	row := s.db.QueryRow(
		`SELECT id, type, name FROM rockets where id=$1;`,
		id,
	)
	err := row.Scan(&rkt.ID, &rkt.Type, &rkt.Name)
	if err != nil {
		log.Print(err.Error())
		return rocket.Rocket{}, err
	}
	return rkt, nil
}

Conclusion

Awesome, we have now fully implemented the AddRocket gRPC handler function and we have validated that we can both insert rockets into the database and retrieve the rockets based on their UUID.