Repo setup for go that lets you use transactions transparently

repo.go

package repo

import (
	"context"
	"database/sql/driver"

	"github.com/jmoiron/sqlx"
)

// can be either a *sqlx.DB or a *sqlx.Tx
// should have methods that are common to both
type executor interface {
	sqlx.ExtContext
	SelectContext(ctx context.Context, dest interface{}, query string, args ...interface{}) error
	GetContext(ctx context.Context, dest interface{}, query string, args ...interface{}) error
}

type Repo interface {
	Begin(ctx context.Context) (Repo, error)
	// has Commit and Rollback sigs
	driver.Tx
  
	// TODD ADD YOUR OTHER METHODS HERE
	InsertFoo(context.Context, *Foo) error
}

// Our implementation
type SqlRepo struct {
	DB *sqlx.DB
	// if this is a normal instance it'll be *sql.DB, otherwise a *sqlx.Tx
	executor
}

func (r SqlRepo) Begin(ctx context.Context) (Repo, error) {
	exr, err := r.DB.BeginTxx(ctx, &sql.TxOptions{})

	if err != nil {
		return nil, err
	}
	return SqlRepo{DB: r.DB, executor: exr}, nil
}

func (r SqlRepo) Commit() (err error) {
	if e, ok := r.executor.(*sqlx.Tx); ok {
		return e.Commit()
	}
	return errors.New("not in a transaction")
}

func (r SqlRepo) Rollback() error {
	if e, ok := r.executor.(*sqlx.Tx); ok {
		return e.Rollback()
	}
	return errors.New("not in a transaction")

}

type Foo struct {
	ID string
	Name string
	CreatedAt time.Time `db:"created_at"`
}

func (r SqlRepo) InsertFoo(ctx context.Context, thing *Foo) error {
	return r.executor.GetContext(ctx, thing, `INSERT INTO foo (name) VALUES ($1)
                  RETURNING id, created_at
                  `, thing.Name)
}