在Go lang的一个事务中使用* sql.DB对象运行多个funcs的惯用方式

Question

Let we have 2 methods

func createClient(db *sql.DB, ...) error // creates a new client
func createOrder(db *sql.DB, ...) error // creates a new order

Each of these method can be run on some *sql.DB, for example,

var mainDb *sql.DB // initialized somewhere in main() method

func orderHandler(r,w) {
   ...
   err := createOrder(mainDb, ...)
   ...
}

But what if i want to run both these methods in one transaction. For example,

func importOrdersHandler(r,w) {
     ...
     tx, err:= mainDb.Begin()
     ...
     err = createClient(tx, clientData) // but method defined on *sql.DB, not *sql.Tx ?!
     err = createOrder(tx, orderData)
     ...

My solution:

Define a wrapper around *sql.DB, *sql.Tx:

type Database struct {
   db *sql.DB
   tx *sql.Tx
}

// Redefine all standart methods from sql package, such as
// Exec(...)
// Query(..)
// QueryRow(...)

// Also method to run commands in one transaction:

func TransactionDo(db *sql.DB, body func(*Database) error) error {
  tx, err :=  db.Begin()
  ...
  d, err := NewDb(nil, tx)
  ....
  err = body(d)
  ...
  return tx.Commit()
}

In this way our ordersImportHandler can be realized like that:

 func importOrdersHandler(r,w) {

   for row := range parseFile(formFile(r)) {
     ...
     err := TransactionDo(mainDb, func(d *Database) error {
        err = createClient(d, clientData)
        ...
        err = createOrder(d, orderData)
    // if an error occurs in TransactionDo then transaction wiil be
    // rollbacked, else commit it

createClient, createOrder must be rewrited to use *Database object insted of *sql.DB

What do you think about such solution? May be there another better and idiomatic way to do that

Answer 1

I used an interface (that the library squirrel also uses)

type Database interface {
    Exec(query string, args ...interface{}) (sql.Result, error)
    Query(query string, args ...interface{}) (*sql.Rows, error)
    QueryRow(query string, args ...interface{}) *sql.Row
}

Then you can just pass write the functions

func createClient(db *Database, ...) error // creates a new client
func createOrder(db *Database, ...) error // creates a new order