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getting-started

πŸš€ Getting Started with express-cargo​

This document provides a minimum configuration guide for quickly experiencing express-cargo in a TypeScript + Express environment. The examples are based on pnpm + Node.js 18 or later.

1. Requirements​

  • Node.js 18 or later (LTS recommended)

Package Manager: npm | yarn | pnpm β†’ This document uses pnpm.

Since express-cargo uses Decorator + Metadata, TypeScript is recommended.

2. Installing Node.js​

Install the LTS version appropriate for your OS from the official website below.

Verify installation:

node -v
pnpm -v

If successful, the version will be displayed.

3. Create a new project (pnpm)​

pnpm​

mkdir express-cargo-example
cd express-cargo-example
pnpm init

4. Set up the TypeScript environment​

4-1. Install TypeScript and development dependencies​

pnpm add -D typescript ts-node @types/node

4-2. Create tsconfig.json​

pnpm tsc --init
{
  "compilerOptions": {
    ...,
    "experimentalDecorators": true,     // express-cargo required
    "emitDecoratorMetadata": true,      // use type metadata
    ...
  },
  ...
}

⚠️ experimentalDecorators, emitDecoratorMetadata Without it, validation/transformation in express-cargo will not work.

5. Install express & express-cargo​

pnpm add express express-cargo
pnpm add -D @types/express
pnpm add reflect-metadata

6. Base server + express-cargo settings​

6-1. src/app.ts​

import express from 'express'
import { bindingCargo, getCargo, Body, Query, Header, Params, Min, Max, Equal, NotEqual, Prefix, Suffix } from 'express-cargo'
import errorHandlerRouter from './errorHandler'

const app = express()

const port = process.env.PORT || 3000

app.use(express.json())
app.use(express.urlencoded({ extended: true }))

app.use(errorHandlerRouter)

app.listen(port, () => {console.log(`Example app listening on port ${port}`)})

class ExampleRequest {
  @Body() // Extract fields from the request body
  @Equal('1') // If the value is not "1", a validation error occurs
  id!: string
}

app.post('/example', bindingCargo(ExampleRequest), (req, res) => { // bindingCargo(Class): Request β†’ DTO conversion + validation
  const cargo = getCargo<ExampleRequest>(req) // Return a validated type-safe object
  res.json(cargo)
})

7. Run​

npm run dev

test request:

POST http://localhost:3000/example
Content-Type: application/json

{
  "id": "1"
}

response:

{ "id": "1" }
  • ❌ "id": "2" β†’ Validation Error occurs