wire-learn

Small Gin + GORM (SQLite) sample project with a simple user lookup API.

Learn Steps

1. Manually build a Gin + GORM project using global variables.
2. Refactor to manual dependency wiring (no globals).
3. Use a simple wire package to centralize construction and injection.

Manual Wiring (step by step)

1. Create core providers

• core.NewDB() opens SQLite and runs migrations.
• core.NewLogger() builds the app logger.

2. Create services

• service.NewUserService(db, logger) depends on DB + logger.

3. Create handlers

• api.NewUserApi(userService) depends on the service.

4. Create router

• router.NewRouter(userApi) registers routes with handlers.

5. Start server

• main.go calls wire.InitWire() and then Run().

This keeps dependencies explicit and avoids package-level globals.

How wire Works Here

This project uses a small manual wiring function (not Google Wire).

• wire.InitWire() is a composition root.
• It constructs dependencies in order (DB → Logger → Service → API → Router).
• It passes instances down the chain so each layer receives what it needs.

Flow:

NewDB → NewLogger → NewUserService → NewUserApi → NewRouter

Requirements

• Go 1.25+

Install

go mod tidy

Run

go run main.go

Server starts on :80.

API

• GET /api/user?id=<id>

Example:

curl "http://localhost:80/api/user?id=1"

Project Structure

api/        HTTP handlers
core/       DB and logger setup
model/      GORM models
router/     Gin routes
service/    Business logic
wire/       Manual wiring/initialization

Notes

• SQLite database file: db.test
• If a user ID does not exist, the API returns 404.