Restful API中的错误处理方法

{
 "message": "Validation Failed",
 "errors": [
 {
  "resource": "Issue",
  "field": "title",
  "code": "missing_field"
 }
 ]
}

{
 "error": {
 "errors": [
  {
  "domain": "global",
  "reason": "insufficientFilePermissions",
  "message": "The user does not have sufficient permissions for file {fileId}."
  }
 ],
 "code": 403,
 "message": "The user does not have sufficient permissions for file {fileId}."
 }
}

{
 "error": {
 "message": "Message describing the error", 
 "type": "OAuthException",
 "code": 190,
 "error_subcode": 460,
 "error_user_title": "A title",
 "error_user_msg": "A message",
 "fbtrace_id": "EJplcsCHuLu"
 }
}

{
 "errors": [
 {
  "message": "Sorry, that page does not exist",
  "code": 34
 }
 ]
}

{
 "code": 21211,
 "message": "The 'To' number 5551234567 is not a valid phone number.",
 "more_info": "https://www.twilio.com/docs/errors/21211",
 "status": 400
}

// Node.js
if (!res.body.title) {
 res.statusCode = 400
}

if (!user) {
 res.statusCode = 401
}

if (!post) {
 res.statusCode = 404
}

if (!res.body.title) {
 throw new Error(ERROR.FORMAT_INVALID)
}

if (!user) {
 throw new Error(ERROR.LOGIN_REQUIRED)
}

if (!post) {
 throw new Error(ERROR.DATA_NOT_FOUND)
}

if (post.creator.id !== user.id) {
 throw new Error(ERROR.PERMISSION_DENIED)
}

{
 "type": "",
 "code": 0,
 "message": "",
 "detail": ""
}

const ERROR = {
 FORMAT_INVALID: 'FORMAT_INVALID',
 DATA_NOT_FOUND: 'DATA_NOT_FOUND',
 DATA_EXISTED: 'DATA_EXISTED',
 DATA_INVALID: 'DATA_INVALID',
 LOGIN_REQUIRED: 'LOGIN_REQUIRED',
 PERMISSION_DENIED: 'PERMISSION_DENIED'
}

const ERROR_MAP = {
 FORMAT_INVALID: {
  code: 1,
  message: 'The request format is invalid'
 },
 DATA_NOT_FOUND: {
  code: 2,
  message: 'The data is not found in database'
 },
 DATA_EXISTED: {
  code: 3,
  message: 'The data has exist in database'
 },
 DATA_INVALID: {
  code: 4,
  message: 'The data is invalid'
 },
 LOGIN_REQUIRED: {
  code 5,
  message: 'Please login first'
 },
 PERMISSION_DENIED: {
  code: 6,
  message: 'You have no permission to operate'
 }
}

class CError extends Error {
 constructor(type, detail) {
  super()
  Error.captureStackTrace(this, this.constructor)

  let error = ERROR_MAP[type]
  if (!error) {
   error = {
    code: 999,
    message: 'Unknow error type'
   }
  }

  this.name = 'CError'
  this.type = error.code !== 999 ? type : 'UNDEFINED'
  this.code = error.code
  this.message = error.message
  this.detail = detail
 }
}

// in controller
if (!user) {
 throw new CError(ERROR.LOGIN_REQUIRED, 'You should login first')
}

if (!req.body.title) {
 throw new CError(ERROR.FORMAT_INVALID, 'Title is required')
}

if (!post) {
 throw new CError(ERROR.DATA_NOT_FOUND, 'The post you required is not found')
}

module.exports = async function errorHandler (ctx, next) {
 try {
  await next()
 } catch (err) {

  let status

  switch (err.type) {
   case ERROR.FORMAT_INVALID:
   case ERROR.DATA_EXISTED:
   case ERROR.DATA_INVALID:
    status = 400
    break
   case ERROR.LOGIN_REQUIRED:
    status = 401
   case ERROR.PERMISSION_DENIED:
    status = 403
   case ERROR.DATA_NOT_FOUND:
    status = 404
    break
   default:
    status = 500
  }

  ctx.status = status
  ctx.body = err
 }
}

// in app.js
app.use(errorHandler)
app.use(router.routes())