oniontx

oniontx

oniontx allows to move transferring transaction management from the Persistence (repository) layer to the Application (service) layer using owner defined contract.

🔴 NOTE: Transactor was designed to work with only the same instance of the "repository" (*sql.DB, etc.)

The key features:

• default implementation for stdlib
• default implementation for popular libraries
• custom implementation's contract
• simple testing with testing frameworks

stdlib package

Transactor implementation for stdlib:

// Look at to `github.com/kozmod/oniontx` to see `Transactor` implementation for standard library
package main

import (
	"context"
	"database/sql"
	"fmt"
	"log"

	ostdlib "github.com/kozmod/oniontx/stdlib"
)

func main() {
	var (
		db *sql.DB // database instance

		tr = ostdlib.NewTransactor(db)
		r1 = repoA{t: tr}
		r2 = repoB{t: tr}
	)

	err := tr.WithinTx(context.Background(), func(ctx context.Context) error {
		err := r1.Insert(ctx, "repoA")
		if err != nil {
			return err
		}
		err = r2.Insert(ctx, "repoB")
		if err != nil {
			return err
		}
		return nil
	})

	if err != nil {
		log.Fatal(err)
	}
	
}

type repoA struct {
	t *ostdlib.Transactor
}

func (r *repoA) Insert(ctx context.Context, val string) error {
	ex := r.t.GetExecutor(ctx)
	_, err := ex.ExecContext(ctx, `INSERT INTO tx (text) VALUES ($1)`, val)
	if err != nil {
		return fmt.Errorf("repoA.Insert: %w", err)
	}
	return nil
}

type repoB struct {
	t *ostdlib.Transactor
}

func (r *repoB) Insert(ctx context.Context, val string) error {
	ex := r.t.GetExecutor(ctx)
	_, err := ex.ExecContext(ctx, `INSERT INTO tx (text) VALUES ($1)`, val)
	if err != nil {
		return fmt.Errorf("repoB.Insert: %w", err)
	}
	return nil
}

test/integration module contains more complicated example.

Default implementation examples for libs

Examples of default implementation of Transactor (sqlx, pgx, gorm, redis, mongo):

• sqlx
• pgx
• gorm
• redis
• mongo

Custom implementation

If it's required, oniontx allowed opportunity to implements custom algorithms for maintaining transactions (examples).

Interfaces:

type (
	// Mandatory
	TxBeginner[T Tx] interface {
		comparable
		BeginTx(ctx context.Context) (T, error)
	}
	
	// Mandatory
	Tx interface {
		Rollback(ctx context.Context) error
		Commit(ctx context.Context) error
	}

	// Optional - using to putting/getting transaction from `context.Context` 
	// (library contains default `СtxOperator` implementation)
	СtxOperator[T Tx] interface {
		Inject(ctx context.Context, tx T) context.Context
		Extract(ctx context.Context) (T, bool)
	}
)

Examples

❗ ️This examples based on stdlib pacakge.

TxBeginner and Tx implementations:

// Prepared contracts for execution
package db

import (
	"context"
	"database/sql"

	"github.com/kozmod/oniontx"
)

// Executor represents common methods of sql.DB and sql.Tx.
type Executor interface {
	ExecContext(ctx context.Context, query string, args ...any) (sql.Result, error)
}

// DB is sql.DB wrapper, implements oniontx.TxBeginner.
type DB struct {
	*sql.DB
}

func (db *DB) BeginTx(ctx context.Context) (*Tx, error) {
	var txOptions sql.TxOptions
	for _, opt := range opts {
		opt.Apply(&txOptions)
	}
	tx, err := db.DB.BeginTx(ctx, &txOptions)
	return &Tx{Tx: tx}, err
}

// Tx is sql.Tx wrapper, implements oniontx.Tx.
type Tx struct {
	*sql.Tx
}

func (t *Tx) Rollback(_ context.Context) error {
	return t.Tx.Rollback()
}

func (t *Tx) Commit(_ context.Context) error {
	return t.Tx.Commit()
}

Repositories implementation:

package repoA

import (
	"context"
	"fmt"

	"github.com/kozmod/oniontx"

	"github.com/user/some_project/internal/db"
)

type RepositoryA struct {
	Transactor *oniontx.Transactor[*db.DB, *db.Tx]
}

func (r RepositoryA) Insert(ctx context.Context, val int) error {
	var executor db.Executor
	executor, ok  := r.Transactor.TryGetTx(ctx)
	if !ok {
		executor = r.Transactor.TxBeginner()
	}
	_, err := executor.ExecContext(ctx, "UPDATE some_A SET value = $1", val)
	if err != nil {
		return fmt.Errorf("update 'some_A': %w", err)
	}
	return nil
}

package repoB

import (
	"context"
	"fmt"
	
	"github.com/kozmod/oniontx"
	
	"github.com/user/some_project/internal/db"
)

type RepositoryB struct {
	Transactor *oniontx.Transactor[*db.DB, *db.Tx]
}

func (r RepositoryB) Insert(ctx context.Context, val int) error {
	var executor db.Executor
	executor, ok := r.Transactor.TryGetTx(ctx)
	if !ok {
		executor = r.Transactor.TxBeginner()
	}
	_, err := executor.ExecContext(ctx, "UPDATE some_A SET value = $1", val)
	if err != nil {
		return fmt.Errorf("update 'some_A': %w", err)
	}
	return nil
}

UseCase implementation:

package usecase

import (
	"context"
	"fmt"
)

type (
	// transactor is the contract of  the oniontx.Transactor
	transactor interface {
		WithinTx(ctx context.Context, fn func(ctx context.Context) error) (err error)
	}

	// Repo is the contract of repositories
	repo interface {
		Insert(ctx context.Context, val int) error
	}
)

type UseCase struct {
	RepoA repo
	RepoB repo

	Transactor transactor
}

func (s *UseCase) Exec(ctx context.Context, insert int) error {
	err := s.Transactor.WithinTx(ctx, func(ctx context.Context) error {
		if err := s.RepoA.Insert(ctx, insert); err != nil {
			return fmt.Errorf("call repository A: %w", err)
		}
		if err := s.RepoB.Insert(ctx, insert); err != nil {
			return fmt.Errorf("call repository B: %w", err)
		}
		return nil
	})
	if err != nil {
		return fmt.Errorf(" execute: %w", err)
	}
	return nil
}

Configuring:

package main

import (
	"context"
	"database/sql"
	"os"

	oniontx "github.com/kozmod/oniontx"
	
	"github.com/user/some_project/internal/repoA"
	"github.com/user/some_project/internal/repoB"
	"github.com/user/some_project/internal/usecase"
)


func main() {
	var (
		database *sql.DB // database pointer

		wrapper    = &db.DB{DB: database}
		operator   = oniontx.NewContextOperator[*db.DB, *db.Tx](&wrapper)
		transactor = oniontx.NewTransactor[*db.DB, *db.Tx](wrapper, operator)

		repositoryA = repoA.RepositoryA{
			Transactor: transactor,
		}
		repositoryB = repoB.RepositoryB{
			Transactor: transactor,
		}

		useCase = usecase.UseCase{
			RepoA: &repositoryA,
			RepoB: &repositoryB,
			Transactor:  transactor,
		}
	)

	err := useCase.Exec(context.Background(), 1)
	if err != nil {
		os.Exit(1)
	}
}

Execution transaction in the different use cases

Execution the same transaction for different usecases with the same oniontx.Transactor instance

UseCases:

package a

import (
	"context"
	"fmt"
)

type (
	// transactor is the contract of  the oniontx.Transactor
	transactor interface {
		WithinTx(ctx context.Context, fn func(ctx context.Context) error) (err error)
	}

	// Repo is the contract of repositories
	repoA interface {
		Insert(ctx context.Context, val int) error
		Delete(ctx context.Context, val float64) error
	}
)

type UseCaseA struct {
	Repo repoA

	Transactor transactor
}

func (s *UseCaseA) Exec(ctx context.Context, insert int, delete float64) error {
	err := s.Transactor.WithinTx(ctx, func(ctx context.Context) error {
		if err := s.Repo.Insert(ctx, insert); err != nil {
			return fmt.Errorf("call repository - insert: %w", err)
		}
		if err := s.Repo.Delete(ctx, delete); err != nil {
			return fmt.Errorf("call repository - delete: %w", err)
		}
		return nil
	})
	if err != nil {
		return fmt.Errorf("usecaseA - execute: %w", err)
	}
	return nil
}

package b

import (
	"context"
	"fmt"
)

type (
	// transactor is the contract of  the oniontx.Transactor
	transactor interface {
		WithinTx(ctx context.Context, fn func(ctx context.Context) error) (err error)
	}

	// Repo is the contract of repositories
	repoB interface {
		Insert(ctx context.Context, val string) error
	}

	// Repo is the contract of the useCase
	useCaseA interface {
		Exec(ctx context.Context, insert int, delete float64) error
	}
)

type UseCaseB struct {
	Repo     repoB
	UseCaseA useCaseA

	Transactor transactor
}

func (s *UseCaseB) Exec(ctx context.Context, insertA string, insertB int, delete float64) error {
	err := s.Transactor.WithinTx(ctx, func(ctx context.Context) error {
		if err := s.Repo.Insert(ctx, insertA); err != nil {
			return fmt.Errorf("call repository - insert: %w", err)
		}
		if err := s.UseCaseA.Exec(ctx, insertB, delete); err != nil {
			return fmt.Errorf("call usecaseB - exec: %w", err)
		}
		return nil
	})
	if err != nil {
		return fmt.Errorf("execute: %w", err)
	}
	return nil
}

Main:

package main

import (
	"context"
	"database/sql"
	"os"

	oniontx "github.com/kozmod/oniontx"

	"github.com/user/some_project/internal/db"
	"github.com/user/some_project/internal/repoA"
	"github.com/user/some_project/internal/repoB"
	"github.com/user/some_project/internal/usecase/a"
	"github.com/user/some_project/internal/usecase/b"
)

func main() {
	var (
		database *sql.DB // database pointer

		wrapper    = &db.DB{DB: database}
		operator   = oniontx.NewContextOperator[*db.DB, *db.Tx](&wrapper)
		transactor = oniontx.NewTransactor[*db.DB, *db.Tx](wrapper, operator)

		useCaseA = a.UseCaseA{
			Repo: repoA.RepositoryA{
				Transactor: transactor,
			},
		}

		useCaseB = b.UseCaseB{
			Repo: repoB.RepositoryB{
				Transactor: transactor,
			},
			UseCaseA: &useCaseA,
		}
	)

	err := useCaseB.Exec(context.Background(), "some_to_insert_useCase_A", 1, 1.1)
	if err != nil {
		os.Exit(1)
	}
}

Testing

test package contains useful examples for creating unit test:

• vektra/mockery + stretchr/testify
• go.uber.org/mock/gomock + stretchr/testify
• gojuno/minimock + stretchr/testify