feat: Impl event while refactoring user domain

README.md

@@ -376,3 +376,36 @@ functionalities well decoupled and interfaces well defined.
 
 I will add some tests for existing code and then it's time to move on to
 my core business logic.
+
+### 2024/10/16
+
+I am facing a design problem. My way to implement the business logic is to
+first write the core logic code in the domain service level. It will help me
+to identify if there are any missing part in my model design. Thus, when
+some of the business logic is done, I can create database migrations and then
+implement the adapter level's code.
+
+The problem is that my design depends heavily on the database. Taking the
+example of adding an expense to en event.
+
+Input is a valid `ExpenseDTO` which has the `event`, `paiements` and
+`receptions`. What I must do is to open a database transaction where I:
+
+1. Get the Event. (Most importantly the `TotalAmount`)
+2. For each `paiemnt` and `reception` create a transaction related to the
+`User`. And insert them into the database.
+3. Update the `TotalAmount`
+4. Update the caches if any
+
+If any step fails, the transaction rolls back.
+
+This has barely no logic at all. I think it is not suitable to try to tie
+this operation to the domain model.
+
+However, there is something that worth a domain model level method, that
+is to calculate the share of each members of the event, where we will have
+the list of members and the amount of balance they have. And then we will
+do the calculate and send back a list of money one should pay for another.
+
+Finally, I think the business logic is still too simple to be put into a
+"Domain". For now, the service layer is just enough.

internal/howmuch/adapter/controller/usecasemock/testuserusecase.go

@@ -35,7 +35,10 @@ func NewtestUserUsecase() usecase.User {
 	return &testUserUsecase{}
 }
 
-func (*testUserUsecase) Create(ctx context.Context, u *model.UserCreateDTO) (*model.User, error) {
+func (*testUserUsecase) Create(
+	ctx context.Context,
+	u *model.UserCreateDTO,
+) (*model.UserInfoVO, error) {
 	return nil, nil
 }
 
@@ -53,3 +56,11 @@ func (*testUserUsecase) Exist(ctx context.Context, u *model.UserExistDTO) error
 	// Should never reach here
 	return nil
 }
+
+func (*testUserUsecase) GetUserBaseVOByID(
+	ctx context.Context,
+	userID int,
+) (*model.UserBaseVO, error) {
+	// TODO:
+	return nil, nil
+}

internal/howmuch/adapter/repo/sqlc/user.sql

@@ -30,3 +30,8 @@ RETURNING *;
 SELECT id, email, first_name, last_name, password, created_at, updated_at
     FROM "user"
     WHERE email = $1;
+
+-- name: GetUserByID :one
+SELECT id, email, first_name, last_name, password, created_at, updated_at
+    FROM "user"
+    WHERE id = $1;

internal/howmuch/adapter/repo/sqlc/user.sql.go

@@ -31,6 +31,27 @@ func (q *Queries) GetUserByEmail(ctx context.Context, email string) (User, error
 	return i, err
 }
 
+const getUserByID = `-- name: GetUserByID :one
+SELECT id, email, first_name, last_name, password, created_at, updated_at
+    FROM "user"
+    WHERE id = $1
+`
+
+func (q *Queries) GetUserByID(ctx context.Context, id int32) (User, error) {
+	row := q.db.QueryRowContext(ctx, getUserByID, id)
+	var i User
+	err := row.Scan(
+		&i.ID,
+		&i.Email,
+		&i.FirstName,
+		&i.LastName,
+		&i.Password,
+		&i.CreatedAt,
+		&i.UpdatedAt,
+	)
+	return i, err
+}
+
 const insertUser = `-- name: InsertUser :one
 
 INSERT INTO "user" (

internal/howmuch/adapter/repo/user.go

@@ -108,3 +108,24 @@ func (ur *userRepository) GetByEmail(ctx context.Context, email string) (*model.
 		UpdatedAt: userDB.CreatedAt,
 	}, nil
 }
+
+func (ur *userRepository) GetByID(ctx context.Context, id int) (*model.UserPO, error) {
+	queries := sqlc.New(ur.db)
+	userDB, err := queries.GetUserByID(ctx, int32(id))
+	if errors.Is(err, pgx.ErrNoRows) {
+		// No query error, but user not found
+		return nil, nil
+	} else if err != nil {
+		return nil, err
+	}
+
+	return &model.UserPO{
+		ID:        int(userDB.ID),
+		Email:     userDB.Email,
+		FirstName: userDB.FirstName,
+		LastName:  userDB.LastName,
+		Password:  userDB.Password,
+		CreatedAt: userDB.CreatedAt,
+		UpdatedAt: userDB.CreatedAt,
+	}, nil
+}

internal/howmuch/model/event.go

@@ -24,12 +24,37 @@ package model
 
 import "time"
 
+// {{{ DTO Data Transfer Object (from controller to service)
+
 type EventCreateDTO struct {
-	Name        string `json:"name"        binding:"requiered"`
-	Description string `json:"description"`
-	OwnerID     int    `json:"owner_id"    binding:"requiered,number"`
+	Name            string   `json:"name"        binding:"requiered"`
+	Description     string   `json:"description"`
+	OwnerID         int      `json:"owner_id"    binding:"requiered,number"`
+	DefaultCurrency Currency `json:"currency"`
 }
 
+// }}}
+// {{{ VO View Object (from service to controller)
+
+type EventInfoVO struct {
+	ID int
+
+	Name        string
+	Description string
+
+	TotalAmount Money
+
+	Owner *UserBaseVO
+
+	CreatedAt time.Time
+	UpdatedAt time.Time
+
+	Users []*UserBaseVO
+}
+
+// }}}
+// {{{ PO Persistant Object (Between the service and the repository)
+
 type EventPO struct {
 	ID int
 
@@ -43,21 +68,26 @@ type EventPO struct {
 	UpdatedAt time.Time
 }
 
-type Event struct {
+// }}}
+// {{{ DO Domain Object (Contains the domain service)
+
+type EventDO struct {
 	ID int
 
 	Name        string
 	Description string
 
 	// lazy get using participation join
-	Users []*User
+	Users []*UserDO
 	// lazy get
 	Expenses []*Expense
 
 	TotalAmount     Money
 	DefaultCurrency Currency
-	Owner           User
+	Owner           *UserDO
 
 	CreatedAt time.Time
 	UpdatedAt time.Time
 }
+
+// }}}

internal/howmuch/model/user.go

@@ -24,6 +24,8 @@ package model
 
 import "time"
 
+// {{{ DTO Data Transfer Object (from controller to service)
+
 type UserCreateDTO struct {
 	Email     string `json:"email"      binding:"required,email"`
 	FirstName string `json:"first_name" binding:"required"`
@@ -36,6 +38,29 @@ type UserExistDTO struct {
 	Password string `json:"password" binding:"required"`
 }
 
+// }}}
+// {{{ VO View Object (from service to controller)
+
+type UserBaseVO struct {
+	ID        int    `json:"id"`
+	FirstName string `json:"first_name"`
+	LastName  string `json:"last_name"`
+}
+
+type UserInfoVO struct {
+	// UserBaseVO
+	ID        int    `json:"id"`
+	FirstName string `json:"first_name"`
+	LastName  string `json:"last_name"`
+
+	Email     string `json:"email"`
+	CreatedAt time.Time
+	UpdatedAt time.Time
+}
+
+// }}}
+// {{{ PO Persistant Object (Between the service and the repository)
+
 type UserPO struct {
 	ID int
 
@@ -48,8 +73,11 @@ type UserPO struct {
 	UpdatedAt time.Time
 }
 
-// User model
-type User struct {
+// }}}
+// {{{ DO Domain Object (Contains the domain service)
+
+// TODO: For now I don't know what to do with this model
+type UserDO struct {
 	ID int
 
 	Email     string
@@ -63,3 +91,5 @@ type User struct {
 	CreatedAt time.Time
 	UpdatedAt time.Time
 }
+
+// }}}

internal/howmuch/usecase/repo/event.go

@@ -0,0 +1,64 @@
+// MIT License
+//
+// Copyright (c) 2024 vinchent <vinchent@vinchent.xyz>
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+package repo
+
+import (
+	"context"
+
+	"git.vinchent.xyz/vinchent/howmuch/internal/howmuch/model"
+)
+
+type EventRepository interface {
+	Create(ctx context.Context, evPO *model.EventPO) (*model.EventPO, error)
+
+	// UpdateInfo updates the event related information (name, descriptions)
+	UpdateInfo()
+
+	Delete() // XXX: Pay attention to the foreign key relationships
+
+	GetByID()
+
+	ListExpensesByUserID()
+
+	// related to events of a user
+	ListEventsByUserID()
+}
+
+type ExpenseRepository interface {
+	Create()
+	Update()
+	Delete() // Delete also the related transactions
+
+	GetByID()
+}
+
+type ParticipationRepository interface {
+	Create()
+	Delete()
+}
+
+type TransactionRepository interface {
+	Create()
+	// Delete() might be handled in the Expense
+	// Transaction is a joined entity, we don't provide diret read operation
+}

internal/howmuch/usecase/repo/user.go

@@ -31,4 +31,5 @@ import (
 type UserRepository interface {
 	Create(ctx context.Context, transaction interface{}, u *model.UserPO) (*model.UserPO, error)
 	GetByEmail(ctx context.Context, email string) (*model.UserPO, error)
+	GetByID(ctx context.Context, id int) (*model.UserPO, error)
 }

internal/howmuch/usecase/usecase/event.go

@@ -0,0 +1,112 @@
+// MIT License
+//
+// Copyright (c) 2024 vinchent <vinchent@vinchent.xyz>
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+package usecase
+
+import (
+	"git.vinchent.xyz/vinchent/howmuch/internal/howmuch/model"
+	"git.vinchent.xyz/vinchent/howmuch/internal/howmuch/usecase/repo"
+	"git.vinchent.xyz/vinchent/howmuch/internal/pkg/log"
+	"golang.org/x/net/context"
+)
+
+type eventUsecase struct {
+	userUC            User
+	eventRepo         repo.EventRepository
+	expenseRepo       repo.ExpenseRepository
+	participationRepo repo.ParticipationRepository
+	transactionRepo   repo.TransactionRepository
+
+	dbRepo repo.DBRepository
+}
+
+// For the controller
+type Event interface{}
+
+func NewEventUsecase(
+	uuc User,
+	ev repo.EventRepository,
+	ex repo.ExpenseRepository,
+	pa repo.ParticipationRepository,
+	tr repo.TransactionRepository,
+	db repo.DBRepository,
+) Event {
+	return &eventUsecase{uuc, ev, ex, pa, tr, db}
+}
+
+func (evuc *eventUsecase) CreateEvent(
+	ctx context.Context,
+	evDTO *model.EventCreateDTO,
+) (*model.EventInfoVO, error) {
+	// transfer evDTO to PO
+
+	evPO := &model.EventPO{
+		Name:            evDTO.Name,
+		Description:     evDTO.Description,
+		OwnerID:         evDTO.OwnerID,
+		TotalAmount:     0,
+		DefaultCurrency: string(evDTO.DefaultCurrency),
+	}
+
+	data, err := evuc.dbRepo.Transaction(
+		ctx,
+		func(txCtx context.Context, tx interface{}) (interface{}, error) {
+			created, err := evuc.eventRepo.Create(ctx, evPO)
+			if err != nil {
+				return nil, err
+			}
+
+			// TODO: App log, maybe can be sent to some third party service.
+			log.InfoLog(
+				"created new event",
+				"name",
+				created.Name,
+				"owner",
+				created.OwnerID,
+			)
+
+			ownerVO, err := evuc.userUC.GetUserBaseVOByID(ctx, created.OwnerID)
+			if err != nil {
+				return nil, err
+			}
+
+			evVO := &model.EventInfoVO{
+				ID:          created.ID,
+				Name:        created.Name,
+				Description: created.Description,
+				TotalAmount: model.MakeMoney(
+					created.TotalAmount,
+					model.Currency(created.DefaultCurrency),
+				),
+				Owner:     ownerVO,
+				CreatedAt: created.CreatedAt,
+			}
+			return evVO, err
+		})
+	if err != nil {
+		return nil, err
+	}
+
+	res := data.(*model.EventInfoVO)
+
+	return res, err
+}

internal/howmuch/usecase/usecase/repomock/testuserrepo.go

@@ -50,7 +50,10 @@ func (tur *TestUserRepository) Create(
 	return &user, nil
 }
 
-func (ur *TestUserRepository) GetByEmail(ctx context.Context, email string) (*model.UserPO, error) {
+func (tur *TestUserRepository) GetByEmail(
+	ctx context.Context,
+	email string,
+) (*model.UserPO, error) {
 	hashedPwd, _ := bcrypt.GenerateFromPassword([]byte("strongHashed"), 12)
 	switch email {
 	case "a@b.c":
@@ -67,3 +70,20 @@ func (ur *TestUserRepository) GetByEmail(ctx context.Context, email string) (*mo
 
 	return nil, UserTestDummyErr
 }
+
+func (tur *TestUserRepository) GetByID(ctx context.Context, id int) (*model.UserPO, error) {
+	hashedPwd, _ := bcrypt.GenerateFromPassword([]byte("strongHashed"), 12)
+	switch id {
+	case 123:
+		return &model.UserPO{
+			ID:       123,
+			Email:    "a@b.c",
+			Password: string(hashedPwd),
+		}, nil
+	case 456:
+		return nil, UserTestDummyErr
+	case 789:
+		return nil, nil
+	}
+	return nil, UserTestDummyErr
+}

internal/howmuch/usecase/usecase/user.go

@@ -60,8 +60,9 @@ type userUsecase struct {
 }
 
 type User interface {
-	Create(ctx context.Context, u *model.UserCreateDTO) (*model.User, error)
+	Create(ctx context.Context, u *model.UserCreateDTO) (*model.UserInfoVO, error)
 	Exist(ctx context.Context, u *model.UserExistDTO) error
+	GetUserBaseVOByID(ctx context.Context, userID int) (*model.UserBaseVO, error)
 }
 
 func NewUserUsecase(r repo.UserRepository, d repo.DBRepository) User {
@@ -71,7 +72,10 @@ func NewUserUsecase(r repo.UserRepository, d repo.DBRepository) User {
 	}
 }
 
-func (uuc *userUsecase) Create(ctx context.Context, u *model.UserCreateDTO) (*model.User, error) {
+func (uuc *userUsecase) Create(
+	ctx context.Context,
+	u *model.UserCreateDTO,
+) (*model.UserInfoVO, error) {
 	// Hash the password
 	encrypted, err := bcrypt.GenerateFromPassword([]byte(u.Password), 12)
 	if err != nil {
@@ -100,9 +104,9 @@ func (uuc *userUsecase) Create(ctx context.Context, u *model.UserCreateDTO) (*mo
 			log.InfoLog(
 				"created new user",
 				"email",
-				u.Email,
+				created.Email,
 				"name",
-				fmt.Sprintf("%s %s", u.FirstName, u.LastName),
+				fmt.Sprintf("%s %s", created.FirstName, created.LastName),
 			)
 
 			return created, err
@@ -115,15 +119,11 @@ func (uuc *userUsecase) Create(ctx context.Context, u *model.UserCreateDTO) (*mo
 
 	userPO := data.(*model.UserPO)
 
-	user := &model.User{
+	user := &model.UserInfoVO{
 		ID:        userPO.ID,
 		Email:     userPO.Email,
-		Password:  userPO.Password,
 		FirstName: userPO.FirstName,
 		LastName:  userPO.LastName,
-
-		EventIDs: []int{}, // Unfilled
-
 		CreatedAt: userPO.CreatedAt,
 		UpdatedAt: userPO.UpdatedAt,
 	}
@@ -151,3 +151,19 @@ func (uuc *userUsecase) Exist(ctx context.Context, u *model.UserExistDTO) error
 
 	return nil
 }
+
+func (uuc *userUsecase) GetUserBaseVOByID(
+	ctx context.Context,
+	userID int,
+) (*model.UserBaseVO, error) {
+	got, err := uuc.userRepo.GetByID(ctx, userID)
+	if err != nil {
+		return nil, err
+	}
+	userBaseVo := &model.UserBaseVO{
+		ID:        got.ID,
+		FirstName: got.FirstName,
+		LastName:  got.LastName,
+	}
+	return userBaseVo, nil
+}

internal/howmuch/usecase/usecase/user_test.go

@@ -29,7 +29,6 @@ import (
 	"git.vinchent.xyz/vinchent/howmuch/internal/howmuch/model"
 	"git.vinchent.xyz/vinchent/howmuch/internal/howmuch/usecase/usecase/repomock"
 	"github.com/stretchr/testify/assert"
-	"golang.org/x/crypto/bcrypt"
 )
 
 func TestCreateUser(t *testing.T) {
@@ -42,23 +41,13 @@ func TestCreateUser(t *testing.T) {
 			LastName:  "Bond",
 			Password:  "verystrong",
 		}
-		want := &model.User{
-			ID:        123,
-			Email:     input.Email,
-			FirstName: input.FirstName,
-			LastName:  input.LastName,
-			// Password is hashed
-			Password: "verystrong",
+		want := &model.UserInfoVO{
+			ID: 123,
 		}
 
 		got, err := userUsecase.Create(ctx, input)
 		assert.NoError(t, err)
 		assert.Equal(t, want.ID, got.ID)
-
-		assert.NoError(
-			t,
-			bcrypt.CompareHashAndPassword([]byte(got.Password), []byte(want.Password)),
-		)
 	})
 
 	t.Run("duplicate create", func(t *testing.T) {