Control de errores.

Formas de reportar errores.

Reporte explícito, usando throw
Reporte silencioso, notificando el error en la misma respuesta de los métodos.

Caso de estudio.

interface.js --> connector.js --> server.js

Conector.

const server = require('./server')

exports.makeRequest = function () {
  // more code...
  return server.response()
}

REPORTE DE ERROR DE FORMA SILENCIOSA

server.js caso de éxito

exports.response = function () {
  // more code...
  return { // Correct response
    ok: true,
    data: [1, 2, 3, 4, 5],
  }
}

interface.js

const connector = require('./connector')

const response = connector.makeRequest()

console.log('Response from server')
console.log(response)

console.log('---------------------------')
console.log('Proccess data: item + 1')
for (const data of response.data) {
  console.log(data + 1)
}

Output

Response from server
{ data: [ 1, 2, 3, 4, 5 ] }
---------------------------
Proccess data: item + 1
2
3
4
5
6

server.js, caso de fallo

exports.response = function () {

  return { // Incorrect response
    ok: false,
    message: 'The data is not available',
  }
}

Traza del error

Response from server
{ ok: false, message: 'The data is not available' }
---------------------------
Proccess data> item + 1
/home/renier/Development/DESARROLLO/APP_PRUEBAS/ERROR_TEST/interface.js:10
for (const data of response.data) {
                            ^

TypeError: response.data is not iterable
    at Object.<anonymous> (/home/renier/Development/DESARROLLO/APP_PRUEBAS/ERROR_TEST/interface.js:10:29)
    at Module._compile (internal/modules/cjs/loader.js:678:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:689:10)
    at Module.load (internal/modules/cjs/loader.js:589:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:528:12)
    at Function.Module._load (internal/modules/cjs/loader.js:520:3)
    at Function.Module.runMain (internal/modules/cjs/loader.js:719:10)
    at startup (internal/bootstrap/node.js:228:19)
    at bootstrapNodeJSCore (internal/bootstrap/node.js:575:3)

inteface.js control del error

const connector = require('./connector')

const response = connector.makeRequest()

console.log('Response from server')
console.log(response)

console.log('---------------------------')
console.log('Proccess data: item + 1')
if (response.data) {
  for (const data of response.data) {
    console.log(data + 1)
  }
} else {
  console.log(response.message)
}

¿Qué pasa si connector.js usa data?

const server = require('./server')

exports.makeRequest = function () {
  const response = server.response()
  count += response.data.length // To do something
  return response
}

Tendría que hacer control de error también.

const server = require('./server')

exports.makeRequest = function () {
  const response = server.response()
  if (response.data) {
    count += response.data.length // To do something
    return response
  } else {
    return response
  }  
}

REPORTE DE ERROR DE FORMA EXPLÍCITA

server.js caso de éxito.

exports.response = function () {
  return [1, 2, 3, 4, 5] // Direct response
}

interface.js

const connector = require('./connector')

const response = connector.makeRequest()

console.log('Response from server')
console.log(response)

console.log('---------------------------')
console.log('Proccess data: item + 1')
for (const data of response) {
  console.log(data + 1)
}

Output

Response from server
{ data: [ 1, 2, 3, 4, 5 ] }
---------------------------
Proccess data> item + 1
2
3
4
5
6

server.js caso de fallo

exports.response = function () {
  throw new Error('The data is not available')
}

Traza del error

/home/renier/Development/DESARROLLO/APP_PRUEBAS/ERROR_TEST/server.js:15
  throw new Error('The data is not available')
  ^

Error: The data is not available
    at Object.exports.response (/home/renier/Development/DESARROLLO/APP_PRUEBAS/ERROR_TEST/server.js:15:9)
    at Object.exports.makeRequest (/home/renier/Development/DESARROLLO/APP_PRUEBAS/ERROR_TEST/connector.js:4:17)
    at Object.<anonymous> (/home/renier/Development/DESARROLLO/APP_PRUEBAS/ERROR_TEST/interface.js:4:23)
    at Module._compile (internal/modules/cjs/loader.js:678:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:689:10)
    at Module.load (internal/modules/cjs/loader.js:589:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:528:12)
    at Function.Module._load (internal/modules/cjs/loader.js:520:3)
    at Function.Module.runMain (internal/modules/cjs/loader.js:719:10)
    at startup (internal/bootstrap/node.js:228:19)

inteface control del error

const connector = require('./connector')

const response = connector.makeRequest()

console.log('Response from server')
console.log(response)

console.log('---------------------------')
console.log('Proccess data: item + 1')
try {
  for (const data of response.data) {
    console.log(data + 1)
  }
} catch(e) {
  console.log(e.message)
}

¿Qué pasa si connector.js usa data?

const server = require('./server')

exports.makeRequest = function () {
  const response = server.response()
  count += response.data.length // To do something
  return response
}

Diferencia entre las dos formas de control de error.

if (response.data) {
  for (const data of response.data) {
    console.log(data + 1)
  }
} else {
  console.log(response.message)
}

//-------------------------------------

try {
  for (const data of response.data) {
    console.log(data + 1)
  }
} catch(e) {
  console.log(e.message)
}

ERRORES EN API REST

Rest está sobre Http.

Utiliza el mismo mecanismo de error de http: Http Status

1xx: InformationalCommunicates transfer protocol-level information.
2xx: SuccessIndicates that the client’s request was accepted successfully.
3xx: RedirectionIndicates that the client must take some additional action in order to complete their request.
4xx: Client ErrorThis category of error status codes points the finger at clients.
5xx: Server ErrorThe server takes responsibility for these error status codes.

Algunos códigos.

200 (OK)
201 (Created)
202 (Accepted)
204 (No Content)
301 (Moved Permanently)
302 (Found)
400 (Bad Request)
401 (Unauthorized)
403 (Forbidden)
404 (Not Found)

405 (Method Not Allowed)
406 (Not Acceptable)
412 (Precondition Failed)
415 (Unsupported Media Type)
500 (Internal Server Error)
501 (Not Implemented)

Uso de códigos de texto vs Http Status

http_status: 400
{
    message: "The data is not available",
    code: "data_not_available"
}

if (error.code == 'data_not_available') {
    // ......
}

Uso de códigos de texto vs Http Status

if (error.status == 410) { // data not available
    // ......
}

http_status: 410
{
    message: "The data is not available",
    code: "data_not_available"
}

Algo que nunca se debe hacer.

def get(self, request, *args, **kwargs):
        ga_service = GoogleAnaltyticsService()

        try:
            chat_platform_service = ChatPlatformService(request.user.organization)
            members = chat_platform_service.get_members()
            return Response(dict(ok=True, members=members), status=status.HTTP_200_OK)
        except Exception as e:
            logger.error(str(e))
            ga_service.track_event(
                user_id=None,
                category="Platform - Core - Exception",
                action="Error catched on {}".format(request.user.organization.get_main_chat_platform_integration()),
                label=str(e)
            )
            return Response(dict(ok=False, detail=str(e)), status=status.HTTP_200_OK)