Marketplace App Backend

This repository is a Spring Boot REST API for a neighborhood marketplace where users can create listings, discover local deals, authenticate through multiple sign-in flows, and message other users about items.

What This Demonstrates

• Built a Java 17 / Spring Boot 3 backend with Gradle and layered controller, service, repository, entity, and DTO packages.
• Modeled a marketplace domain with users, listings, conversations, and messages persisted through Spring Data JPA.
• Implemented email/password authentication, BCrypt password hashing, JWT token generation, Google sign-in handoff, and GitHub OAuth code exchange.
• Added marketplace discovery through active listings, user listings, category filtering, and keyword search.
• Supported buyer-seller messaging with paginated conversations, ordered message history, and read/unread state updates.
• Prepared the app for hosted deployment with environment-based configuration, PostgreSQL, Java 17 runtime settings, and a Procfile.

Core Features

Authentication

• Email/password signup and login.
• Password hashing with BCrypt.
• JWT generation with email and user id claims.
• Google auth handoff for users authenticated on the client.
• GitHub OAuth exchange with support for separate web and mobile client credentials.
• Account linking by email when a user signs in through multiple providers.

Marketplace Listings

• Create, read, update, delete, and status-update listing flows.
• Active listing feed ordered by newest first.
• Filter listings by user or category.
• Search listings by title and description.
• Listing DTOs include seller name and profile picture for frontend display.

Conversations And Messaging

• Create or reuse one conversation per buyer, seller, and listing.
• List a user's conversations with pagination and newest activity first.
• Send messages inside a conversation.
• Fetch ordered message history.
• Mark messages as read or unread.

Tech Stack

Area	Technology
Language	Java 17
Framework	Spring Boot 3.5.7
API	Spring Web REST controllers
Security	Spring Security, BCrypt, JWT
Persistence	Spring Data JPA, Hibernate
Database	PostgreSQL
Build	Gradle Wrapper
Config	Environment variables with spring-dotenv

Architecture

flowchart LR
    Client["Web or mobile client"] --> Controllers["REST controllers"]
    Controllers --> Services["Service layer"]
    Services --> Repositories["Spring Data repositories"]
    Repositories --> Database[("PostgreSQL")]
    Controllers --> Jwt["JWT utility"]
    Controllers --> OAuth["Google / GitHub OAuth APIs"]

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erDiagram
    USER ||--o{ LISTINGS : creates
    USER ||--o{ CONVERSATIONS : participates
    LISTINGS ||--o{ CONVERSATIONS : starts
    CONVERSATIONS ||--o{ MESSAGES : contains

    USER {
        long id
        string email
        string name
        string picture
        string googleId
        string githubId
        string roles
    }

    LISTINGS {
        long id
        string title
        decimal price
        string category
        string location
        string status
    }

    CONVERSATIONS {
        long id
        long user1Id
        long user2Id
        long listingId
        datetime lastMessageAt
    }

    MESSAGES {
        long id
        long senderId
        long receiverId
        long conversationId
        string content
        boolean isRead
    }

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API Overview

Auth

Method	Endpoint	Purpose
POST	/api/auth/signup	Register a user with email, name, and password.
POST	/api/auth/login	Authenticate with email/password and receive a JWT.
POST	/api/auth/google	Create or update a user from Google profile data.
POST	/api/auth/github	Exchange a GitHub auth code, fetch profile/email data, and receive a JWT.

Users

Method	Endpoint	Purpose
GET	/api/user/me	Resolve the current user from an authorization header.
GET	/api/user/all	Fetch all users.
GET	/api/user/by-email?email=	Look up a user by email.
GET	/api/user/by-userid?userid=	Look up a user by id.

Listings

Method	Endpoint	Purpose
GET	/api/listings	Fetch all active listings.
POST	/api/listings	Create a new listing.
GET	/api/listings/{id}	Fetch one listing by id.
GET	/api/listings/user/{userId}	Fetch listings for a specific seller.
GET	/api/listings/my-listings	Fetch listings for the authenticated user.
GET	/api/listings/category/{category}	Fetch active listings in a category.
GET	/api/listings/search?keyword=	Search listing title and description.
PUT	/api/listings/{id}	Update a listing.
PATCH	/api/listings/{id}/status?status=	Update listing status.
DELETE	/api/listings/{id}	Delete a listing.

Conversations And Messages

Method	Endpoint	Purpose
POST	/conversations	Create or reuse a conversation for two users and a listing.
GET	/conversations?userId=&page=&size=	List a user's conversations with pagination.
GET	/conversations/{conversationId}/messages	Fetch paginated message history.
POST	/conversations/{conversationId}/messages	Send a message in a conversation.
PATCH	/conversations/{conversationId}/messages/{messageId}/read	Mark a message as read.
PATCH	/conversations/{conversationId}/messages/{messageId}/unread	Mark a message as unread.

Local Development

Prerequisites

• Java 17
• PostgreSQL
• Git
• The included Gradle wrapper (./gradlew)

1. Clone The Repository

git clone <repo-url>
cd MarketPlace_App_Backend

2. Configure Environment Variables

Create a local .env file in the project root. Do not commit this file.

DB_URL=jdbc:postgresql://localhost:5432/hood_deals
DB_USERNAME=your_database_user
DB_PASSWORD=your_database_password

GOOGLE_CLIENT_ID=your_google_client_id
GOOGLE_CLIENT_SECRET=your_google_client_secret

CLIENT_ID=your_github_mobile_client_id
CLIENT_SECRET=your_github_mobile_client_secret
WEB_CLIENT_ID=your_github_web_client_id
WEB_CLIENT_SECRET=your_github_web_client_secret

JWT_SECRET=replace_with_a_64_plus_character_secret_for_hs512_signing
JWT_EXPIRATION=86400000
SERVER_PORT=8080

3. Run The API

./gradlew bootRun

The API will start on the port configured by SERVER_PORT, usually:

http://localhost:8080