Banking app

• The project recreates a banking app like ASB

Stack

• go
• SSR html with htmx

Feature

• Login & Sign up & logout
• Different types of bank accounts: everyday, saver, kiwisaver
• transfers between accounts
• payments

Screenshots

login page

online banking page

transfer page

payments page

File structure

│   .air.toml
│   .gitignore
│   docker-compose.yml
│   Dockerfile
│   go.mod
│   go.sum
│   improvements.md
│   plan.md
│   README.md
│
├───.vscode
│       launch.json
│
├───cmd
│       main.go
│
├───data
│       .gitkeep
│       database.db
│
├───internal
│   │
│   ├───database
│   │       bank-accounts.go
│   │       schema.go
│   │       session.go
│   │       users.go
│   │
│   ├───domain
│   │       bank-account.go
│   │       password.go
│   │       session.go
│   │       user.go
│   │
│   ├───handlers
│   │       auth.go
│   │       bank-accounts.go
│   │       html-pages.go
│   │
│   ├───middleware
│   │       auth.go
│   │
│   ├───server
│   │       routes.go
│   │
│   ├───helpers
│   │       auth.go
│   │       bank-accounts.go
│   │       sessions.go
│   │       user-account.go
│   │
│   └───utils
│           utils.go
│
├───web
│   ├───assets
│   │       default-account.jpg
│   │       dollar-sign-icon.png
│   │       dropdown.js
│   │       everyday-account.jpg
│   │       favicon.png
│   │       kiwisaver-account.jpg
│   │       password-icon.png
│   │       saver-account.jpg
│   │       style.css
│   │       user-icon.png
│   │
│   ├───templates
│   │       account.html
│   │       balance.html
│   │
│   └───views
│           login.html
│           online-banking.html
│           payment.html
│           transfer.html
│
├───screenshots
│       login-page-desktop.png
│       login-page-phone.png
│       online-banking-page-desktop.png
│       online-banking-page-phone.png
│       payments-page-desktop.png
│       payments-page-phone.png
│       transfer-page-desktop.png
│       transfer-page-phone.png
│
└───tmp
        main

Key flow and logic

Auth (signup + login)

• handlers.SignUp → validate → helpers.CreateUserAccount

• CreateUserAccount → hash password → database.CreateUserAccount

• Then createAllAccounts → creates 3 account rows

• Session created via helpers.CreateSession

• Cookie set in setSessionCookie

• handlers.LoginAuth → helpers.ValidLoginCredentials

• If valid → new session → cookie

---

Auth protection

• middleware.RequireAuth
  • Reads session_id cookie
  • Calls database.GetSession
  • Checks expiry
  • Rejects or continues

---

Account data (HTMX)

• Page loads → HTMX calls:

  • /get-welcome-message → handlers.GetWelcomeMessage
  • /account-balance → handlers.GetAccount

• Flow:

  • sessionID → database.GetUserID
  • account type → BankAccountType.GetTableName
  • balance → database.GetAccountBalance

---

Transfers

• handlers.TransferMoney

  • parse → getTransferData
  • validate → helpers.CanTransfer
  • execute → helpers.MakeTransfer

• Core flow:

  • session → userID (GetUserID)
  • map enums → table names
  • call database.MakeTransfer

• DB layer:

  • wrapped in withTx
  • transfer:
    • WithDraw
    • Deposit

---

Payments (to another user)

• handlers.Payment

  • parse → getPaymentData
  • validate → helpers.IsValidPayment
  • execute → helpers.MakePayment

• Key differences:

  • receiver() → gets receiver userID
  • prevents sending to self
  • deposits into default account

---

Transactions (important)

• withTx

  • begin tx
  • run logic
  • rollback on error
  • commit if success

• Ensures:

  • no partial updates
  • withdraw + deposit always linked

---

Validation rules

• isValidAmount

  • amount > 0
  • enough balance

• BankAccountType

  • IsValid
  • CanWithdraw

• Password:

  • Password.IsStrong

---

Database design

• Tables:

  • users
  • sessions
  • everydayAccount, saverAccount, kiwiSaverAccount

• Each account:

  • userID
  • balanceCents

---

Problems issues know constraints

A lot of the current code lacks the go idiomatic style The CSS on a latop screen size looks bad (smaller and bigger ok) The transfer and payment are not beign clear after transaction