README
¶
go-txhelper 
go-txhelper is a module that abstracts database transaction behaviour. It does so by differentiating between Read and Write operations.
It is designed for the use of mappers where you do not know whether you need a transaction or not.
Example
package main
import (
"context"
"errors"
"fmt"
"os"
"github.com/jackc/pgx/v4"
"github.com/jackc/pgx/v4/pgxpool"
"github.com/talon-one/go-txhelper"
)
func main() {
ctx := context.Background()
pool, err := pgxpool.Connect(ctx, os.Getenv("DATABASE_URL"))
if err != nil {
panic(err)
}
defer pool.Close()
// create a users table
_, err = pool.Exec(ctx, `CREATE TABLE IF NOT EXISTS users (
id INTEGER PRIMARY KEY,
name TEXT NOT NULL
)`)
if err != nil {
panic(err)
}
um, err := NewUserMapper(pool)
if err != nil {
panic(err)
}
// we need to close the mapper at the end of our business logic
defer um.Close(ctx)
id := 1
wantedName := "Joe"
// Get the UserName of the specified user
currentName, err := um.GetUserName(ctx, id)
if err != nil {
if !errors.Is(err, pgx.ErrNoRows) {
panic(err)
}
// if there are no rows for this id create a user
if err := um.CreateUser(ctx, id, wantedName); err != nil {
panic(err)
}
fmt.Printf("Created User (id=%d, name=%s)\n", id, wantedName)
return
}
if currentName != wantedName {
if err := um.UpdateUserName(ctx, id, wantedName); err != nil {
panic(err)
}
fmt.Printf("Updated User (id=%d, name=%s)\n", id, wantedName)
return
}
fmt.Printf("nothing to do (id=%d, name=%s)\n", id, currentName)
}
type UserMapper struct {
txh *txhelper.TxHelper
}
func NewUserMapper(pool *pgxpool.Pool) (*UserMapper, error) {
txh, err := txhelper.New(pool, nil)
if err != nil {
return nil, err
}
return &UserMapper{
txh: txh,
}, nil
}
func (um *UserMapper) CreateUser(ctx context.Context, id int, name string) error {
executor, err := um.txh.GetExecutor(ctx, txhelper.InsertOperation)
if err != nil {
return err
}
_, err = executor.Exec(ctx, "INSERT INTO users VALUES ($1, $2)", id, name)
return err
}
func (um *UserMapper) GetUserName(ctx context.Context, id int) (string, error) {
executor, err := um.txh.GetExecutor(ctx, txhelper.ReadOperation)
if err != nil {
return "", err
}
row := executor.QueryRow(ctx, "SELECT name FROM users WHERE id = $1", id)
var name string
if err := row.Scan(&name); err != nil {
return "", err
}
return name, nil
}
func (um *UserMapper) UpdateUserName(ctx context.Context, id int, newName string) error {
executor, err := um.txh.GetExecutor(ctx, txhelper.UpdateOperation)
if err != nil {
return err
}
_, err = executor.Exec(ctx, "UPDATE users SET name = $1 WHERE id = $2", newName, id)
return err
}
func (um *UserMapper) Close(ctx context.Context) error {
return um.txh.Commit(ctx)
}
Documentation
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Index ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type Executor ¶
type Executor interface {
Exec(ctx context.Context, sql string, arguments ...interface{}) (commandTag pgconn.CommandTag, err error)
Query(ctx context.Context, sql string, args ...interface{}) (pgx.Rows, error)
QueryRow(ctx context.Context, sql string, args ...interface{}) pgx.Row
}
Executor is a type that implements the Exec, Query and QueryRow of pgx, it can be used to hide the types pgxpool.Pool, pgx.Conn,...
type Hooks ¶ added in v0.0.2
type Hooks struct {
BeforeStartTransaction func(*TxHelper, *pgxpool.Pool, context.Context) error
AfterStartTransaction func(*TxHelper, *pgxpool.Pool, pgx.Tx, context.Context) error
BeforeCommit func(*TxHelper, *pgxpool.Pool, pgx.Tx, context.Context) error
AfterCommit func(*TxHelper, *pgxpool.Pool, pgx.Tx, context.Context) error
BeforeRollback func(*TxHelper, *pgxpool.Pool, pgx.Tx, context.Context) error
AfterRollback func(*TxHelper, *pgxpool.Pool, pgx.Tx, context.Context) error
}
Hooks can be used to perform custom logic before or after certain events.
type Operation ¶
type Operation int
Operation defines the operation that will be performed on the database.
const ( // ReadOperation should be used for read only activities, such as selecting data. ReadOperation Operation = 1 << iota // InsertOperation should be used for the INSERT operation. InsertOperation // UpdateOperation should be used for the UPDATE operation. UpdateOperation // DeleteOperation should be used for the DELETE operation. DeleteOperation )
type TxHelper ¶
type TxHelper struct {
// contains filtered or unexported fields
}
TxHelper is a helper that can be used inside mappers. Its purpose is to assist the mappers with transaction handling.
func New ¶
New creates a new TxHelper that can be used inside mappers. Its purpose is to assist the mappers with transaction handling.
func (*TxHelper) GetExecutor ¶
GetExecutor gets the executor for the specified operation. The executor can be used to query the database. GetExecutor will start and return a transaction if there is no existing transaction AND if the operation is either a InsertOperation, UpdateOperation or DeleteOperation. In case of a non existing transaction and a ReadOperation GetExecutor will NOT start a transaction.
Source Files
Directories