Backend Crowdfunding

A REST API for crowdfunding campaigns and donations, written in Go. Users can register, create campaigns, and donate through a payment gateway. Built with Gin, GORM, and PostgreSQL, with JWT authentication and Midtrans for payments.

Features

• Users — register, login, email availability check, avatar upload
• Campaigns — list, detail, create, update, image upload (with ownership checks)
• Transactions — create donations, list per campaign and per user
• Payments — Midtrans Snap integration with a webhook for status updates
• Auth — stateless JWT, enforced via middleware

Highlights

• UUID identifiers — every resource uses a non-sequential UUID, so IDs can't be guessed or enumerated from the API.
• Compile-time dependency injection with google/wire — no runtime reflection or service locator.
• Atomic payments — transaction status and campaign totals are updated inside a single database transaction.
• Cloud storage — uploads go to Cloudflare R2 (S3-compatible) with a local-disk fallback for development.
• Operability — graceful shutdown, request-id tracing, structured JSON logs, and database connection retry on startup.

Architecture

The code is organised by domain. Each domain owns its entity, repository (database access), and service (business logic). HTTP handlers depend only on the service interfaces, and dependencies are wired together with google/wire.

config/        Environment configuration
database/      GORM connection setup
auth/          JWT generation and validation
user/          User domain (entity, repository, service)
campaign/      Campaign domain
transaction/   Transaction domain
payment/       Midtrans gateway
storage/       File uploads (Cloudflare R2 or local disk)
handler/       Gin HTTP handlers, auth middleware, request logging
helper/        Shared API response helpers
migrations/    SQL schema migrations
docs/          Generated Swagger/OpenAPI spec
wire.go        Dependency graph (compile-time DI)

Request flow: handler → service (interface) → repository (interface) → PostgreSQL. Because services and repositories are interfaces, the business logic is unit tested with in-memory mocks and no database.

Getting Started

Run with Docker (recommended)

cp .env.example .env          # set JWT_SECRET_KEY at minimum
docker compose up --build

This starts PostgreSQL and the API. The service listens on http://localhost:8080. If 8080 or 5432 are already in use, override HOST_APP_PORT / HOST_DB_PORT in your .env.

Run locally

Requires Go 1.25+ and a running PostgreSQL instance.

cp .env.example .env          # adjust DB credentials and JWT_SECRET_KEY
make migrate-up DATABASE_URL="postgres://postgres:postgres@127.0.0.1:5432/crowdfunding?sslmode=disable"
make run

Migrations use golang-migrate. If you don't have the CLI:

go install -tags 'postgres' github.com/golang-migrate/migrate/v4/cmd/migrate@latest

Configuration

All configuration comes from environment variables (a local .env is loaded when present).

Variable	Description	Default
APP_PORT	HTTP port	8080
DB_HOST	PostgreSQL host	127.0.0.1
DB_PORT	PostgreSQL port	5432
DB_USER	PostgreSQL user	postgres
DB_PASSWORD	PostgreSQL password	(empty)
DB_NAME	Database name	crowdfunding
JWT_SECRET_KEY	Signing key for JWT (required)	—
MIDTRANS_SERVER_KEY	Midtrans server key	—
MIDTRANS_CLIENT_KEY	Midtrans client key	—
MIDTRANS_ENABLED	Turn the live checkout on/off	false
SUPPORT_EMAIL	Contact shown when in demo mode	hi@wikukarno.dev
R2_ACCOUNT_ID	Cloudflare R2 account id	—
R2_ACCESS_KEY_ID	R2 access key	—
R2_SECRET_ACCESS_KEY	R2 secret key	—
R2_BUCKET	R2 bucket name	—
R2_PUBLIC_URL	Public base URL for uploaded files	—

File storage

Avatar and campaign images are uploaded to Cloudflare R2 (S3-compatible) through the AWS SDK. When the R2_* variables are empty the app falls back to local disk under ./images so development works without cloud credentials.

Payments (demo mode)

The live Midtrans checkout is gated behind MIDTRANS_ENABLED. When it's off (the default), POST /transactions returns 503 and no pending row is written, so a public demo never creates real Snap tokens. GET /config reports the current state (and SUPPORT_EMAIL) so the web client can show a "contact support to enable a live demo" prompt instead — keeping the server flag as the single source of truth. As a safety net, MidtransConfig.Available() also stays in demo mode when the flag is on but the keys are missing, so a half-configured deploy can't advertise a checkout that would fail.

API

Interactive Swagger UI is available at http://localhost:8080/swagger/index.html once the server is running. Regenerate the spec after changing annotations with make docs.

Base path: /api/v1. Protected routes need an Authorization: Bearer <token> header.

Method	Endpoint	Auth	Description
GET	/health		Health check
GET	/config		Public client config (payments on/off, support email)
POST	/users		Register a user
POST	/sessions		Login
POST	/email_checkers		Check email availability
POST	/avatars	✓	Upload avatar
GET	/users/fetch	✓	Fetch current user
GET	/campaigns		List campaigns (?user_id= opt.)
GET	/campaigns/:id		Campaign detail
POST	/campaigns	✓	Create campaign
PUT	/campaigns/:id	✓	Update campaign
POST	/campaign-images	✓	Upload campaign image
GET	/campaigns/:id/transactions	✓	Transactions of a campaign
GET	/transactions	✓	Current user's transactions
POST	/transactions	✓	Create a donation
POST	/transactions/notification		Midtrans payment webhook

Testing

make test     # go test -race ./...
make cover    # coverage report per function

Tech Stack

Go · Gin · GORM · PostgreSQL · JWT · google/wire · Swagger (swaggo) · Cloudflare R2 (S3) · Midtrans · Docker

License

MIT © Wiku Karno