Where To Find What

name: Where to Find What description: A quick lookup guide for navigating a repository: where to find endpoints, business logic, models, tests, configs, docs, scripts, plus search patterns and commands

Where to Find What

Overview

Reference guide ที่บอกว่า "หา X อยู่ไหน" สำหรับ common patterns ใน codebase เช่น หา API endpoints, database models, tests, configs ช่วยให้ AI และคนค้นหาได้เร็ว

Why This Matters

• Fast lookup: รู้ทันทีว่าต้องไปไฟล์ไหน
• No guessing: ไม่ต้อง grep หลายรอบ
• Pattern recognition: เข้าใจ conventions ของ repo
• Consistent navigation: ทุกคนหาเหมือนกัน

Core Concepts

1. Code Categories

• HTTP layer: routes/controllers/middleware
• Domain layer: use-cases/services/entities/policies
• Infrastructure: DB clients/repos, queues, external API adapters
• Shared: types, utils, constants, logging/errors

2. Search Patterns

• หาตาม “entry points”: routes, controllers, handlers, index, main
• หาตาม “contracts”: OpenAPI, schema, dto, types, events
• หาตาม “dependencies”: import paths, client constructors, env var names

3. Naming Conventions

• ยึดตาม suffixes (*.service.ts, *.repository.ts, *.controller.ts)
• tests mirror source path
• configs อยู่ที่ root/config ตามมาตรฐานเดียวกัน

4. Common Lookups

• “endpoint อยู่ไหน” → src/api/routes / src/routes
• “business rule อยู่ไหน” → src/domain/* (หรือ src/modules/*/domain ใน monorepo)
• “DB schema อยู่ไหน” → prisma/schema.prisma / migrations/ / src/db/models

5. Cross-References

• endpoint ↔ request/response types ↔ domain service ↔ repository ↔ migration
• event producer ↔ schema registry ↔ consumer handler ↔ DLQ runbook
• feature flag ↔ rollout plan ↔ dashboards/alerts

6. Test Locations

• unit tests อยู่ใกล้ domain หรือ mirror path ใน tests/
• integration/e2e แยกเป็นโฟลเดอร์เฉพาะ เพื่อไม่ปนกับ unit
• fixtures/mocks มีตำแหน่งชัด (เช่น tests/__fixtures__, tests/__mocks__)

7. Config Locations

• runtime env vars: .env.example
• app config: config/ หรือ src/config/
• infra deploy: Dockerfile, k8s/, .github/workflows/, terraform/

8. Documentation Locations

• API: docs/api/ หรือ docs/api.yaml
• Architecture: docs/architecture/
• Runbooks: docs/runbooks/
• ADRs: docs/adr/

Quick Start

# Add a `WHERE.md` at repo root or `docs/`:
# - “Finding Code / Tests / Config / Docs” sections
# - Concrete path patterns + examples (not theory)
# - 5–10 copy/paste search commands for the repo

Production Checklist

• Common lookups documented
• Naming conventions explained
• Search patterns provided
• Updated when structure changes
• Easy to scan/search

Where to Find What Template

# WHERE.md - Quick Lookup Guide

## 🔍 Finding Code

### API Endpoints
```
Want: REST endpoint for /users
Look: src/api/routes/users.ts
Pattern: src/api/routes/{resource}.ts
```

### Business Logic
```
Want: User creation logic
Look: src/domain/users/services/createUser.ts
Pattern: src/domain/{entity}/services/{action}.ts
```

### Database Models
```
Want: User schema
Look: src/infrastructure/db/models/user.ts
Pattern: src/infrastructure/db/models/{entity}.ts
```

### Database Migrations
```
Want: Migration files
Look: prisma/migrations/
Pattern: prisma/migrations/{timestamp}_{name}/
```

### Type Definitions
```
Want: API request/response types
Look: src/api/types/{resource}.ts

Want: Domain types
Look: src/domain/{entity}/types.ts
```

### External API Integrations
```
Want: Stripe integration
Look: src/infrastructure/stripe/

Want: Email service
Look: src/infrastructure/email/
```

## 🧪 Finding Tests

### Unit Tests
```
Source: src/domain/users/services/createUser.ts
Test: tests/domain/users/services/createUser.test.ts
Pattern: tests/{mirror of src path}.test.ts
```

### Integration Tests
```
Look: tests/integration/{feature}/
Pattern: tests/integration/{feature}/*.test.ts
```

### E2E Tests
```
Look: tests/e2e/
Pattern: tests/e2e/{flow}.spec.ts
```

## ⚙️ Finding Configuration

| Config Type | Location |
|-------------|----------|
| Environment vars | `.env.example` |
| App config | `config/` |
| TypeScript | `tsconfig.json` |
| Linting | `.eslintrc.js` |
| Testing | `jest.config.js` |
| Docker | `Dockerfile`, `docker-compose.yml` |
| CI/CD | `.github/workflows/` |

## 📚 Finding Documentation

| Doc Type | Location |
|----------|----------|
| API reference | `docs/api/` |
| Architecture | `docs/architecture/` |
| Runbooks | `docs/runbooks/` |
| ADRs | `docs/adr/` |

## 🔧 Finding Scripts

| Script | Location | Usage |
|--------|----------|-------|
| Dev server | `npm run dev` | Local development |
| Build | `npm run build` | Production build |
| Migrations | `npm run db:migrate` | Run migrations |
| Seed data | `npm run db:seed` | Populate test data |

## 🗂️ By File Type

| I need... | File pattern | Example |
|-----------|--------------|---------|
| Controller | `*Controller.ts` | `UsersController.ts` |
| Service | `*Service.ts` | `UserService.ts` |
| Repository | `*Repository.ts` | `UserRepository.ts` |
| Middleware | `*Middleware.ts` | `AuthMiddleware.ts` |
| Validator | `*Validator.ts` | `UserValidator.ts` |
| DTO | `*Dto.ts` | `CreateUserDto.ts` |
```

Search Commands

# Find file by name
fd "UserService"

# Find definition
grep -r "class UserService" src/

# Find usage
grep -r "UserService" src/ --include="*.ts"

# Find tests for a file
fd "createUser.test" tests/

Anti-patterns

1. Inconsistent structure: ไฟล์คล้ายกันอยู่คนละที่
2. No pattern: ต้อง grep ทุกครั้ง
3. Hidden files: สำคัญแต่หายาก
4. No documentation: รู้แค่ในหัวคนเดิม

Integration Points

• IDE search configurations
• AI retrieval playbooks
• Onboarding materials
• Code review guides

Further Reading

• Project Structure Patterns
• Clean Architecture