express-rest-error
Clean error throwing/handling for Express REST apps using the Service layer pattern
Install
npm i -S express-rest-error
Example
import { validationError, errorHandler } from 'express-rest-error'
import express from 'express'
const app = express()
async function helloService(name) {
if (!name) throw validationError('Must specify name.')
return `Hello ${name}!`
}
app.get('/hello', async (req, res, next) => {
try {
const result = await helloService(req.query.name)
res.json({ result })
} catch (err) {
next(err)
}
})
app.use(errorHandler({ debug: true }))
Throwing Errors
You may throw any of the following types of errors with an optional error message
.
throw validationError( message, details )
- Appropriate for missing required fields or invalid input.
- Sets the response status code to
400
.
throw authRequired( message, details )
- Appropriate when token or authentication is missing.
- Sets the response status code to
401
.
throw accessDenied( message, details )
- Appropriate when the user making the request does not have permission to the resource.
- Sets the response status code to
403
.
throw notFound( message, details )
- Appropriate when the requested resource does not exist.
- Sets the response status code to
404
.
throw customError( message, details, httpStatus )
- Appropriate for when custom errors are necessary
Handling Errors
This error handler will detect which type of error was thrown and set the status code accordingly.
Note: You should define the error handler last, after all other middleware.
app.use(errorHandler({ debug: true }))
Error Handler Options
-
debug
{Boolean} - (optional) returns debug output (stack trace, request data) -
transform
{Function} - (optional) intercept error before sending to client
app.use(errorHandler({
debug: true,
transform: ({ err, req, res, responseBody }) => {
res.setHeader('X-Warning', 'Stop sending bad requests.')
return responseBody;
}
}))