README.md

@@ -421,28 +421,27 @@ The following basic use cases are to be implemented at the first time.
 
 - [X] A user signs up
 - [X] A user logs in
-- [ ] A user lists their events (pagination)
+- [X] A user lists their events (pagination)
-- [ ] A user sees the detail of an event (description, members, amount)
+- [X] A user sees the detail of an event (description, members, amount)
-- [ ] A user sees the expenses of an event (total amount, personal expenses, pagination)
+- [] A user sees the expenses of an event (total amount, personal expenses, pagination)
-- [ ] A user sees the detail of an expense: (time, amount, payers, recipients)
+- [] A user sees the detail of an expense: (time, amount, payers, recipients)
-- [ ] A user adds an expense
+- [] A user adds an expense
-- [ ] A user updates/changes an expense (may handle some extra access control)
+- [] A user updates/changes an expense (may handle some extra access control)
-- [ ] A user can pay the debt to other members (just a special case of expense)
+- [] A user deletes an expense (may handle some extra access control)
-- [ ] A user creates an event (and participate to it)
+- [] A user restore a deleted expense
-- [ ] A user updates the event info
+- [] A user can pay the debt to other members
-- [ ] A user invites another user by sending a mail with a token.
+- [X] A user creates an event (and participate to it)
-- [ ] A user joins an event by accepting an invitation
+- [X] A user updates the event info
-- [ ] A user cannot see other user's information
+- [X] A user invites another user by sending a mail with a token.
-- [ ] A user cannot see the events that they didn't participated in.
+- [X] A user joins an event by accepting an invitation
+- [] ~A user quits an event (they cannot actually, but we can make as if they quitted)~ 
+**No we can't quit!**
+- [] A user cannot see other user's information
+- [] A user cannot see the events that they didn't participated in.
 
 For the second stage:
 
-- [ ] A user can archive an event
+- [] A user can archive an event
-- [ ] A user deletes an expense (may handle some extra access control)
-- [ ] A user restore a deleted expense
-- [ ] Audit log for expense updates/deletes
-- [ ] ~A user quits an event (they cannot actually, but we can make as if they
-quitted)~ **No we can't quit!**
 
 With those functionalities, there will be an usable product. And then we can
 work on other aspects. For example:
@@ -492,30 +491,3 @@ GROUP BY
     o.id, o.first_name, o.last_name;
 
 ```
-
-### 2024/10/19
-
-I don't plan to handle deletions at this first stage, but I note down what I
-have thought of.
-
-1. Just delete. But keep a replica at the front end of the object that we are
-deleting. And propose an option to restore (so a new record is added to the DB)
-2. Just delete, but wait. The request is sent to a queue with a timeout of
-several seconds, if the user regrets, they can cancel the request. This can be
-done on the front, but also on the back. I think it is better to do in on the
-front-end.
-3. Never deletes. But keep a state in the DB `deleted`. They will just be
-ignored when counting.
-4. Deletes when doing database cleanup. They lines deleted will be processed
-when we cleanup the DB. And they will be definitely deleted at that time.
-
-I can create a audit log table to log all the critical
-changes in my `expense` table (update or delete).
-
-Finished with the basic SQL commands. Learned a lot from SQL about `JOIN`,
-aggregation and `CTE`. SQL itself has quite amount of things to learn, this
-is on my future learning plan!
-
-_I found it quite interesting that simply with SQL, we can simulate the most
-business logic. It is a must-have competence for software design and
-development._

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

@@ -1,72 +0,0 @@
--- name: InsertExpense :one
-INSERT INTO "expense" (
-    created_at, updated_at, amount, currency, event_id, name, place
-) VALUES ( $1, $2, $3, $4, $5, $6, $7 )
-RETURNING *;
-
--- name: DeleteExpense :exec
-DELETE FROM "expense" WHERE id = $1;
-
--- name: DeleteTransactionsOfExpenseID :exec
-DELETE FROM "transaction" WHERE transaction.expense_id = $1;
-
--- name: UpdateExpenseByID :one
-UPDATE "expense"
-SET updated_at = $2, amount = $3, currency = $4, name = $5, place = $6
-WHERE id = $1
-RETURNING *;
-
--- name: ListExpensesByEventID :many
-SELECT
-    ex.id, ex.created_at, ex.updated_at, ex.amount, ex.currency, ex.event_id,
-    ex.name, ex.place
-FROM "expense" ex
-JOIN "event" ev ON ev.id = ex.event_id
-WHERE ev.id = $1;
-
--- name: ListExpensesByEventIDByUserID :many
-SELECT
-    ex.id, ex.created_at, ex.updated_at, ex.amount, ex.currency, ex.event_id,
-    ex.name, ex.place
-FROM "expense" ex
-JOIN "event" ev ON ev.id = ex.event_id
-WHERE ev.id = $1;
-
--- name: GetExpenseByID :one
-WITH payer_transaction as (
-    SELECT pt.expense_id,
-        json_agg(json_build_object(
-            'payer_id', p.id,
-            'payer_first_name', p.first_name,
-            'payer_last_name', p.last_name,
-            'amount', pt.amount,
-            'currency', pt.currency
-        )) AS payments
-    FROM "transaction" pt
-    JOIN "user" p ON p.id = pt.user_id
-    WHERE pt.is_income = FALSE
-    GROUP BY pt.expense_id
-), -- For each expense, aggregate payment info
-recipient_transaction as (
-    SELECT rt.expense_id,
-        json_agg(json_build_object(
-            'recipient_id', p.id,
-            'recipient_first_name', p.first_name,
-            'recipient_last_name', p.last_name,
-            'amount', rt.amount,
-            'currency', rt.currency
-        )) AS benefits
-    FROM "transaction" rt
-    JOIN "user" p ON p.id = rt.user_id
-    WHERE rt.is_income = TRUE
-    GROUP BY rt.expense_id
-) -- For each expense, aggregate benefits info
-SELECT
-    ex.id, ex.created_at, ex.updated_at, ex.amount, ex.currency, ex.event_id,
-    ex.name, ex.place,
-    COALESCE(pt.payments, '[]') AS payments,
-    COALESCE(rt.benefits, '[]') AS benefits
-FROM "expense" ex
-LEFT JOIN "payer_transaction" pt ON pt.expense_id = ex.id
-LEFT JOIN "recipient_transaction" rt ON rt.expense_id = ex.id
-WHERE ex.id = $1;

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

@@ -1,264 +0,0 @@
-// Code generated by sqlc. DO NOT EDIT.
-// versions:
-//   sqlc v1.27.0
-// source: expense.sql
-
-package sqlc
-
-import (
-	"context"
-	"database/sql"
-	"encoding/json"
-	"time"
-)
-
-const deleteExpense = `-- name: DeleteExpense :exec
-DELETE FROM "expense" WHERE id = $1
-`
-
-func (q *Queries) DeleteExpense(ctx context.Context, id int32) error {
-	_, err := q.db.ExecContext(ctx, deleteExpense, id)
-	return err
-}
-
-const deleteTransactionsOfExpenseID = `-- name: DeleteTransactionsOfExpenseID :exec
-DELETE FROM "transaction" WHERE transaction.expense_id = $1
-`
-
-func (q *Queries) DeleteTransactionsOfExpenseID(ctx context.Context, expenseID int32) error {
-	_, err := q.db.ExecContext(ctx, deleteTransactionsOfExpenseID, expenseID)
-	return err
-}
-
-const getExpenseByID = `-- name: GetExpenseByID :one
-WITH payer_transaction as (
-    SELECT pt.expense_id,
-        json_agg(json_build_object(
-            'payer_id', p.id,
-            'payer_first_name', p.first_name,
-            'payer_last_name', p.last_name,
-            'amount', pt.amount,
-            'currency', pt.currency
-        )) AS payments
-    FROM "transaction" pt
-    JOIN "user" p ON p.id = pt.user_id
-    WHERE pt.is_income = FALSE
-    GROUP BY pt.expense_id
-), -- For each expense, aggregate payment info
-recipient_transaction as (
-    SELECT rt.expense_id,
-        json_agg(json_build_object(
-            'recipient_id', p.id,
-            'recipient_first_name', p.first_name,
-            'recipient_last_name', p.last_name,
-            'amount', rt.amount,
-            'currency', rt.currency
-        )) AS benefits
-    FROM "transaction" rt
-    JOIN "user" p ON p.id = rt.user_id
-    WHERE rt.is_income = TRUE
-    GROUP BY rt.expense_id
-) -- For each expense, aggregate benefits info
-SELECT
-    ex.id, ex.created_at, ex.updated_at, ex.amount, ex.currency, ex.event_id,
-    ex.name, ex.place,
-    COALESCE(pt.payments, '[]') AS payments,
-    COALESCE(rt.benefits, '[]') AS benefits
-FROM "expense" ex
-LEFT JOIN "payer_transaction" pt ON pt.expense_id = ex.id
-LEFT JOIN "recipient_transaction" rt ON rt.expense_id = ex.id
-WHERE ex.id = $1
-`
-
-type GetExpenseByIDRow struct {
-	ID        int32
-	CreatedAt time.Time
-	UpdatedAt time.Time
-	Amount    int32
-	Currency  string
-	EventID   int32
-	Name      sql.NullString
-	Place     sql.NullString
-	Payments  json.RawMessage
-	Benefits  json.RawMessage
-}
-
-func (q *Queries) GetExpenseByID(ctx context.Context, id int32) (GetExpenseByIDRow, error) {
-	row := q.db.QueryRowContext(ctx, getExpenseByID, id)
-	var i GetExpenseByIDRow
-	err := row.Scan(
-		&i.ID,
-		&i.CreatedAt,
-		&i.UpdatedAt,
-		&i.Amount,
-		&i.Currency,
-		&i.EventID,
-		&i.Name,
-		&i.Place,
-		&i.Payments,
-		&i.Benefits,
-	)
-	return i, err
-}
-
-const insertExpense = `-- name: InsertExpense :one
-INSERT INTO "expense" (
-    created_at, updated_at, amount, currency, event_id, name, place
-) VALUES ( $1, $2, $3, $4, $5, $6, $7 )
-RETURNING id, created_at, updated_at, amount, currency, event_id, name, place
-`
-
-type InsertExpenseParams struct {
-	CreatedAt time.Time
-	UpdatedAt time.Time
-	Amount    int32
-	Currency  string
-	EventID   int32
-	Name      sql.NullString
-	Place     sql.NullString
-}
-
-func (q *Queries) InsertExpense(ctx context.Context, arg InsertExpenseParams) (Expense, error) {
-	row := q.db.QueryRowContext(ctx, insertExpense,
-		arg.CreatedAt,
-		arg.UpdatedAt,
-		arg.Amount,
-		arg.Currency,
-		arg.EventID,
-		arg.Name,
-		arg.Place,
-	)
-	var i Expense
-	err := row.Scan(
-		&i.ID,
-		&i.CreatedAt,
-		&i.UpdatedAt,
-		&i.Amount,
-		&i.Currency,
-		&i.EventID,
-		&i.Name,
-		&i.Place,
-	)
-	return i, err
-}
-
-const listExpensesByEventID = `-- name: ListExpensesByEventID :many
-SELECT
-    ex.id, ex.created_at, ex.updated_at, ex.amount, ex.currency, ex.event_id,
-    ex.name, ex.place
-FROM "expense" ex
-JOIN "event" ev ON ev.id = ex.event_id
-WHERE ev.id = $1
-`
-
-func (q *Queries) ListExpensesByEventID(ctx context.Context, id int32) ([]Expense, error) {
-	rows, err := q.db.QueryContext(ctx, listExpensesByEventID, id)
-	if err != nil {
-		return nil, err
-	}
-	defer rows.Close()
-	var items []Expense
-	for rows.Next() {
-		var i Expense
-		if err := rows.Scan(
-			&i.ID,
-			&i.CreatedAt,
-			&i.UpdatedAt,
-			&i.Amount,
-			&i.Currency,
-			&i.EventID,
-			&i.Name,
-			&i.Place,
-		); err != nil {
-			return nil, err
-		}
-		items = append(items, i)
-	}
-	if err := rows.Close(); err != nil {
-		return nil, err
-	}
-	if err := rows.Err(); err != nil {
-		return nil, err
-	}
-	return items, nil
-}
-
-const listExpensesByEventIDByUserID = `-- name: ListExpensesByEventIDByUserID :many
-SELECT
-    ex.id, ex.created_at, ex.updated_at, ex.amount, ex.currency, ex.event_id,
-    ex.name, ex.place
-FROM "expense" ex
-JOIN "event" ev ON ev.id = ex.event_id
-WHERE ev.id = $1
-`
-
-func (q *Queries) ListExpensesByEventIDByUserID(ctx context.Context, id int32) ([]Expense, error) {
-	rows, err := q.db.QueryContext(ctx, listExpensesByEventIDByUserID, id)
-	if err != nil {
-		return nil, err
-	}
-	defer rows.Close()
-	var items []Expense
-	for rows.Next() {
-		var i Expense
-		if err := rows.Scan(
-			&i.ID,
-			&i.CreatedAt,
-			&i.UpdatedAt,
-			&i.Amount,
-			&i.Currency,
-			&i.EventID,
-			&i.Name,
-			&i.Place,
-		); err != nil {
-			return nil, err
-		}
-		items = append(items, i)
-	}
-	if err := rows.Close(); err != nil {
-		return nil, err
-	}
-	if err := rows.Err(); err != nil {
-		return nil, err
-	}
-	return items, nil
-}
-
-const updateExpenseByID = `-- name: UpdateExpenseByID :one
-UPDATE "expense"
-SET updated_at = $2, amount = $3, currency = $4, name = $5, place = $6
-WHERE id = $1
-RETURNING id, created_at, updated_at, amount, currency, event_id, name, place
-`
-
-type UpdateExpenseByIDParams struct {
-	ID        int32
-	UpdatedAt time.Time
-	Amount    int32
-	Currency  string
-	Name      sql.NullString
-	Place     sql.NullString
-}
-
-func (q *Queries) UpdateExpenseByID(ctx context.Context, arg UpdateExpenseByIDParams) (Expense, error) {
-	row := q.db.QueryRowContext(ctx, updateExpenseByID,
-		arg.ID,
-		arg.UpdatedAt,
-		arg.Amount,
-		arg.Currency,
-		arg.Name,
-		arg.Place,
-	)
-	var i Expense
-	err := row.Scan(
-		&i.ID,
-		&i.CreatedAt,
-		&i.UpdatedAt,
-		&i.Amount,
-		&i.Currency,
-		&i.EventID,
-		&i.Name,
-		&i.Place,
-	)
-	return i, err
-}

internal/howmuch/adapter/repo/sqlc/models.go

@@ -27,17 +27,6 @@ type Event struct {
 	TotalAmount     sql.NullInt32
 }
 
-type Expense struct {
-	ID        int32
-	CreatedAt time.Time
-	UpdatedAt time.Time
-	Amount    int32
-	Currency  string
-	EventID   int32
-	Name      sql.NullString
-	Place     sql.NullString
-}
-
 type Participation struct {
 	ID              int32
 	UserID          int32
@@ -47,17 +36,6 @@ type Participation struct {
 	UpdatedAt       time.Time
 }
 
-type Transaction struct {
-	ID        int32
-	ExpenseID int32
-	UserID    int32
-	Amount    int32
-	Currency  string
-	IsIncome  bool
-	CreatedAt time.Time
-	UpdatedAt time.Time
-}
-
 type User struct {
 	ID        int32
 	Email     string

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

@@ -1,5 +0,0 @@
--- name: InsertTransaction :exec
-INSERT INTO "transaction" (
-    created_at, updated_at, amount, currency, expense_id, user_id, is_income
-) VALUES ( $1, $2, $3, $4, $5, $6, $7 )
-RETURNING *;

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

@@ -1,41 +0,0 @@
-// Code generated by sqlc. DO NOT EDIT.
-// versions:
-//   sqlc v1.27.0
-// source: transaction.sql
-
-package sqlc
-
-import (
-	"context"
-	"time"
-)
-
-const insertTransaction = `-- name: InsertTransaction :exec
-INSERT INTO "transaction" (
-    created_at, updated_at, amount, currency, expense_id, user_id, is_income
-) VALUES ( $1, $2, $3, $4, $5, $6, $7 )
-RETURNING id, expense_id, user_id, amount, currency, is_income, created_at, updated_at
-`
-
-type InsertTransactionParams struct {
-	CreatedAt time.Time
-	UpdatedAt time.Time
-	Amount    int32
-	Currency  string
-	ExpenseID int32
-	UserID    int32
-	IsIncome  bool
-}
-
-func (q *Queries) InsertTransaction(ctx context.Context, arg InsertTransactionParams) error {
-	_, err := q.db.ExecContext(ctx, insertTransaction,
-		arg.CreatedAt,
-		arg.UpdatedAt,
-		arg.Amount,
-		arg.Currency,
-		arg.ExpenseID,
-		arg.UserID,
-		arg.IsIncome,
-	)
-	return err
-}

internal/howmuch/model/expense.go

@@ -24,44 +24,16 @@ package model
 
 import "time"
 
-// {{{ Requrest
-
 type ExpenseRequest struct {
-	Amount   Money         `json:"money"    binding:"required"`
+	Amount       Money         `json:"money"         binding:"required,number"`
-	Payments []Payment     `json:"payments" binding:"required"`
+	PayerIDs     []int         `json:"payer_ids"     binding:"required"`
-	Benefits []Benefit     `json:"benefits" binding:"required"`
+	RecipientIDs []int         `json:"recipient_ids" binding:"required"`
-	EventID  int           `json:"event_id" binding:"required"`
+	EventID      int           `json:"event_id"      binding:"required"`
-	Detail   ExpenseDetail `json:"detail"`
+	Detail       ExpenseDetail `json:"detail"`
 }
 
-// }}}
-// {{{ Response
-
-type ExpensesListResponse struct {
-	ID        int       `json:"id"`
-	CreatedAt time.Time `json:"created_at"`
-	UpdatedAt time.Time `json:"updated_at"`
-
-	Amount  Money `json:"money"`
-	EventID int   `json:"event_id"`
-
-	Detail ExpenseDetail `json:"detail"`
-}
-
-type ExpenseGetResponse Expense
-
-// }}}
-// {{{ Retrieved
-
-type ExpensesListRetrieved ExpensesListResponse
-
-// }}}
-// {{{ Entity
-
 type ExpenseEntity struct {
-	ID        int
+	ID int
-	CreatedAt time.Time
-	UpdatedAt time.Time
 
 	Amount   int
 	Currency string
@@ -70,42 +42,30 @@ type ExpenseEntity struct {
 	// ExpenseDetail
 	Name  string
 	Place string
-}
 
-// }}}
+	CreatedAt time.Time
-// {{{ Domain Models
+	UpdatedAt time.Time
+}
 
 type ExpenseDetail struct {
 	Name  string `json:"name"`
 	Place string `json:"place"`
 }
 
-type Payment struct {
-	PayerID        int    `json:"payer_id"         binding:"required,number"`
-	PayerFirstName string `json:"payer_first_name"`
-	PayerLastName  string `json:"payer_last_name"`
-	Amount         Money  `json:"amount"           binding:"required"`
-}
-
-type Benefit struct {
-	RecipientID        int    `json:"recipient_id"         binding:"required,number"`
-	RecipientFirstName string `json:"recipient_first_name"`
-	RecipientLastName  string `json:"recipient_last_name"`
-	Amount             Money  `json:"amount"               binding:"required"`
-}
-
 type Expense struct {
-	ID        int       `json:"id"`
+	ID int
-	CreatedAt time.Time `json:"created_at"`
-	UpdatedAt time.Time `json:"updated_at"`
 
-	Amount  Money `json:"money"`
+	Amount Money
-	EventID int   `json:"event_id"`
 
-	Detail ExpenseDetail `json:"detail"`
+	// Lazy aggregate using Transaction join
+	PayerIDs []int
 
-	Payments []Payment `json:"payments"`
+	// Lazy aggregate using Transaction join
-	Benefits []Benefit `json:"benefits"`
+	RecipientIDs []int
+
+	EventID int
+	Detail  ExpenseDetail
+
+	CreatedAt time.Time
+	UpdatedAt time.Time
 }
-
-// }}}

internal/howmuch/model/transaction.go

@@ -24,25 +24,18 @@ package model
 
 import "time"
 
-// {{{ Entity
-
 type TransactionEntity Transaction
 
-// }}}
+// Transaction is the association between Expenses and Users
-// {{{ Domain object
-
 type Transaction struct {
 	ID int
 
-	ExpenseID int
+	ExpenseID Expense
 	UserID    int
 	Amount    int
 	Currency  string
-	IsIncome  bool // To note that the direction of the money (payment or income)
+	IsIncome  bool
 
 	CreatedAt time.Time
 	UpdatedAt time.Time
 }
-
-// }}}
-// Transaction is the association between Expenses and Users

migrations/20241019110734_create_transaction_table.postgres.down.sql

@@ -1 +0,0 @@
-

migrations/20241019110734_create_transaction_table.postgres.up.sql

@@ -1,14 +0,0 @@
-CREATE TABLE "transaction" (
-  "id" serial NOT NULL,
-  PRIMARY KEY ("id"),
-  "expense_id" integer NOT NULL,
-  "user_id" integer NOT NULL,
-  "amount" integer NOT NULL,
-  "currency" character varying(255) NOT NULL,
-  "is_income" boolean NOT NULL DEFAULT FALSE,
-  "created_at" date NOT NULL,
-  "updated_at" date NOT NULL
-);
-
-ALTER TABLE "transaction"
-ADD FOREIGN KEY ("user_id") REFERENCES "user" ("id") ON DELETE CASCADE ON UPDATE CASCADE;

migrations/20241019112255_create_expense_table.postgres.down.sql

@@ -1 +0,0 @@
-DROP TABLE "expense";

migrations/20241019112255_create_expense_table.postgres.up.sql

@@ -1,14 +0,0 @@
-CREATE TABLE "expense" (
-  "id" serial NOT NULL,
-  PRIMARY KEY ("id"),
-  "created_at" date NOT NULL,
-  "updated_at" date NOT NULL,
-  "amount" integer NOT NULL,
-  "currency" character varying NOT NULL,
-  "event_id" integer NOT NULL,
-  "name" character varying(255) NULL,
-  "place" character varying(1000) NULL
-);
-
-ALTER TABLE "expense"
-ADD FOREIGN KEY ("event_id") REFERENCES "event" ("id") ON DELETE CASCADE ON UPDATE CASCADE

migrations/20241019112421_fk_transaction_expense.postgres.down.sql

@@ -1 +0,0 @@
-DROP TABLE transaction;

migrations/20241019112421_fk_transaction_expense.postgres.up.sql

@@ -1,2 +0,0 @@
-ALTER TABLE "transaction"
-ADD FOREIGN KEY ("expense_id") REFERENCES "expense" ("id") ON DELETE CASCADE ON UPDATE CASCADE