Expense Reimbursement System (ERS)

Project Overview

The Expense Reimbursement System is a Java Full Stack application that allows employees to submit reimbursement requests and managers to review and resolve them. Built with Spring Boot and React + TypeScript, it features secure session-based authentication, role-based access control, and a responsive Material UI interface.

Technology Stack

Layer	Technology
Frontend	React 18, TypeScript, Vite, Material UI 6
Backend	Spring Boot 3.4, Java 17
Database	PostgreSQL
Testing	JUnit 5, jqwik (property-based), Vitest, fast-check
Auth	Session-based with BCrypt password hashing

Features

Employee

• Register and log in with hashed credentials
• Submit reimbursement requests with validated description and amount
• View all or pending reimbursements
• Edit the description of pending reimbursements

Manager

• Everything an employee can do, plus:
• View and resolve (approve/deny) all reimbursements
• View, delete, and update roles for all users
• Delete confirmation dialog prevents accidental removals

Security and Quality

• BCrypt password hashing — plaintext passwords never stored or logged
• Passwords excluded from all API responses via @JsonProperty(WRITE_ONLY)
• Structured JSON error responses with proper HTTP status codes (401 vs 403)
• Bean Validation on all request bodies
• BigDecimal for monetary amounts (no floating-point rounding)
• @Transactional on multi-step database operations
• SLF4J logging throughout (no System.out.println)
• Centralized CORS configuration, DTO mapping, and session utilities
• Axios 401 interceptor for automatic session-expiry handling
• Role-based route protection on the frontend
• Client-side form validation with accessibility (aria-describedby, semantic HTML)
• Responsive layout with MUI breakpoints and hamburger nav on mobile

Project Structure

P1Backend/                  Spring Boot backend
├── src/main/java/com/revature/
│   ├── config/             CorsConfiguration
│   ├── controllers/        Auth, User, Reimbursement controllers
│   ├── aspects/            AOP auth checks (@AdminOnly)
│   ├── exceptions/         Global exception handler, ErrorResponse, custom exceptions
│   ├── models/             JPA entities, DTOs, DTOMapper
│   ├── repository/         Spring Data JPA repositories
│   ├── services/           Business logic with BCrypt and @Transactional
│   └── util/               SessionUtil
└── src/test/java/          Property-based tests (jqwik)

p1frontend/                 React + TypeScript frontend
├── src/
│   ├── Components/         Navbar, Auth, Reimbursements, Users, DashboardLayout
│   ├── contexts/           AuthContext (userId, username, role, logout)
│   ├── hooks/              useApiQuery (loading, error, refetch)
│   ├── pages/              Employee and Manager dashboards
│   ├── services/           Axios API service with 401 interceptor
│   ├── types/              TypeScript interfaces
│   └── __tests__/          Property-based tests (fast-check + Vitest)
└── .env.example            Environment variable template

Getting Started

Prerequisites

• Java 17+
• Node.js 18+
• PostgreSQL running on localhost:5432
• A database named postgres with a schema named project1

Backend

cd P1Backend
./mvnw spring-boot:run

The API starts on http://localhost:4444. Configure the database connection in src/main/resources/application.properties.

Frontend

cd p1frontend
npm install
npm run dev

The dev server starts on http://localhost:5173. To point at a different backend, create a .env file:

VITE_API_BASE_URL=http://localhost:4444

Running Tests

Backend (excludes the context-load test that requires a live DB):

cd P1Backend
./mvnw test -Dtest='!P1BackendApplicationTests'

Frontend:

cd p1frontend
npm test

API Endpoints

Method	Path	Auth	Description
POST	/auth/login	No	Log in, creates session
POST	/auth/logout	Yes	Invalidate session
POST	/users/register	No	Register new user
GET	/users	Manager	List all users (DTOs)
DELETE	/users/delete/{id}	Yes	Delete a user
PATCH	/users/update-role	Manager	Change user role
POST	/reimbursements/create	Yes	Submit reimbursement
GET	/reimbursements/my-reimbursements	Yes	Current user's reimbursements
GET	/reimbursements/my-pending	Yes	Current user's pending
GET	/reimbursements	Manager	All reimbursements
GET	/reimbursements/pending	Manager	All pending
PATCH	/reimbursements/resolve/{id}	Manager	Approve or deny
PATCH	/reimbursements/update/{id}	Yes	Update description

Author

Adam Abdulkadir