go-transaction-manager

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//go:build with_real_db
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// +build with_real_db
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package pgxv4_test
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import (
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	"context"
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	"fmt"
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	"github.com/jackc/pgx/v4/pgxpool"
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	trmpgx "github.com/avito-tech/go-transaction-manager/drivers/pgxv4/v2"
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	"github.com/avito-tech/go-transaction-manager/trm/v2/manager"
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)
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// Example demonstrates the implementation of the Repository pattern by trm.Manager.
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func Example() {
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	ctx := context.Background()
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	uri := fmt.Sprintf("postgres://%s:%s@%s:%d/%s",
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		"user", "pass", "localhost", 5432, "db",
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	)
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	pool, err := pgxpool.Connect(ctx, uri)
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	checkErr(err)
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	defer pool.Close()
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	sqlStmt := `CREATE TABLE IF NOT EXISTS users_v4 (user_id SERIAL, username TEXT)`
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	_, err = pool.Exec(ctx, sqlStmt)
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	checkErr(err, sqlStmt)
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	r := newRepo(pool, trmpgx.DefaultCtxGetter)
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	trManager := manager.Must(trmpgx.NewDefaultFactory(pool))
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	u := &user{
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		Username: "username",
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	}
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	err = trManager.Do(ctx, func(ctx context.Context) error {
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		if err := r.Save(ctx, u); err != nil {
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			return err
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		}
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		return trManager.Do(ctx, func(ctx context.Context) error {
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			u.Username = "new_username"
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			return r.Save(ctx, u)
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		})
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	})
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	checkErr(err)
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	userFromDB, err := r.GetByID(ctx, u.ID)
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	checkErr(err)
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	fmt.Println(userFromDB)
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	// Output: &{1 new_username}
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}
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type repo struct {
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	db     *pgxpool.Pool
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	getter *trmpgx.CtxGetter
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}
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func newRepo(db *pgxpool.Pool, c *trmpgx.CtxGetter) *repo {
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	repo := &repo{
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		db:     db,
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		getter: c,
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	}
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	return repo
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}
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type user struct {
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	ID       int64
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	Username string
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}
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func (r *repo) GetByID(ctx context.Context, id int64) (*user, error) {
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	query := `SELECT * FROM users_v4 WHERE user_id=$1`
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	conn := r.getter.DefaultTrOrDB(ctx, r.db)
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	row := conn.QueryRow(ctx, query, id)
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	user := &user{}
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	err := row.Scan(&user.ID, &user.Username)
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	if err != nil {
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		return nil, err
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	}
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	return user, nil
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}
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func (r *repo) Save(ctx context.Context, u *user) error {
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	isNew := u.ID == 0
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	conn := r.getter.DefaultTrOrDB(ctx, r.db)
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	if !isNew {
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		query := `UPDATE users_v4 SET username = $1 WHERE user_id = $2`
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		if _, err := conn.Exec(ctx, query, u.Username, u.ID); err != nil {
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			return err
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		}
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		return nil
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	}
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	query := `INSERT INTO users_v4 (username) VALUES ($1) RETURNING user_id`
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	err := conn.QueryRow(ctx, query, u.Username).Scan(&u.ID)
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	if err != nil {
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		return err
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	}
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	return nil
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}
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func checkErr(err error, args ...interface{}) {
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	if err != nil {
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		panic(fmt.Sprint(append([]interface{}{err}, args...)...))
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	}
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}
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