mysql connection.go: invalid connection [duplicate] - mysql

Question

i'm getting Stuck as TRY my first CRUD with MySQL (5.7) using GO lang (1.18). CREATE & READ SQL not return the error, but in UPDATE & DELETE return the error. I was searching and looks like about bad or wrong configuration for connection...but i dont know how to trace it.
Driver MySQL: github.com/go-sql-driver/mysql v1.6.0
My Repo: https://github.com/ramadoiranedar/GO_REST_API
The Error is:
[mysql] 2022/09/22 00:04:44 connection.go:299: invalid connection
driver: bad connection
And i have functions SQL look likes this:
CONNECTION
func NewDB() *sql.DB {
db, err := sql.Open("mysql", "MY_USERNAME:MY_PASSWORD#tcp(localhost:3306)/go_restful_api")
helper.PanicIfError(err)
db.SetMaxIdleConns(5)
db.SetMaxIdleConns(20)
db.SetConnMaxLifetime(60 * time.Minute)
db.SetConnMaxIdleTime(10 * time.Minute)
return db
}
UPDATE
func (repository *CategoryRepositoryImpl) Update(ctx context.Context, tx *sql.Tx, category domain.Category) domain.Category {
SQL := "update category set name = ? where id = ?"
_, err := tx.ExecContext(ctx, SQL, category.Name, category.Id)
helper.PanicIfError(err)
return category
}
DELETE
func (repository *CategoryRepositoryImpl) Delete(ctx context.Context, tx *sql.Tx, category domain.Category) {
SQL := "delete from category where id = ?"
_, err := tx.ExecContext(ctx, SQL, category.Name, category.Id)
helper.PanicIfError(err)
}
CREATE
func (repository *CategoryRepositoryImpl) Create(ctx context.Context, tx *sql.Tx, category domain.Category) domain.Category {
SQL := "insert into category (name) values (?)"
result, err := tx.ExecContext(ctx, SQL, category.Name)
helper.PanicIfError(err)
id, err := result.LastInsertId()
if err != nil {
panic(err)
}
category.Id = int(id)
return category
}
READ
func (repository *CategoryRepositoryImpl) FindAll(ctx context.Context, tx *sql.Tx) []domain.Category {
SQL := "select id, name from category"
rows, err := tx.QueryContext(ctx, SQL)
helper.PanicIfError(err)
var categories []domain.Category
for rows.Next() {
category := domain.Category{}
err := rows.Scan(
&category.Id,
&category.Name,
)
helper.PanicIfError(err)
categories = append(categories, category)
}
return categories
}
func (repository *CategoryRepositoryImpl) FindById(ctx context.Context, tx *sql.Tx, categoryId int) (domain.Category, error) {
SQL := "select id, name from category where id = ?"
rows, err := tx.QueryContext(ctx, SQL, categoryId)
helper.PanicIfError(err)
category := domain.Category{}
if rows.Next() {
err := rows.Scan(&category.Id, &category.Name)
helper.PanicIfError(err)
return category, nil
} else {
return category, errors.New("CATEGORY IS NOT FOUND")
}
}

Answer 1

Long story short: you are using database transactions where you should not.
Keep them for group of writing operations that must succeed.
I would suggest you to redefine your repository and its implementation. The whole idea of splitting layers is to be independant of a repository implementation and to be able to switch from mysql to mongo to postgres, or w/e.
//category_controller.go
type CategoryRepository interface {
Create(ctx context.Context, category domain.Category) domain.Category
Update(ctx context.Context, category domain.Category) domain.Category
Delete(ctx context.Context, category domain.Category)
FindById(ctx context.Context, categoryId int) (domain.Category, error)
FindAll(ctx context.Context) []domain.Category
}
//category_repository_impl.go
type CategoryRepositoryImpl struct {
db *sql.DB
}
func NewCategoryRepository(db *sql.DB) CategoryRepository {
return &CategoryRepositoryImpl{db: db}
}
Please see following gists with modified version of your code files:
https://gist.github.com/audrenbdb/94660f707a206d385c42f64ceb93a4aa