属性未定义但 console.log() 打印属性

Question

I have this function:

async geraQuiz(idEstudante) {
  let idioma = new Array()
  let livrosUnidadesGerarQuiz = new Array()
  const idsClassesEstudante = await this.getIdClassesEstudante(idEstudante) // Here i have this array return: [2,3]

  for(let i=0;i<idsClassesEstudante.length;i++){
   livrosUnidadesGerarQuiz = new Array() // Clear the array
   idioma.push(await this.getDadosClasseIdiomaEstudante(idsClassesEstudante[i]))
   livrosUnidadesGerarQuiz = await this.getLivrosUnidadesGerarQuiz(idsClassesEstudante[i], idBookClasseEstudante[0], qtdQuizGerar)
   idioma[i].quiz = livrosUnidadesGerarQuiz

   console.log(JSON.stringify(idioma))

   console.log(idioma[i].quiz[0])

   ...

In the console.log(idioma) i have this array of objects:

[
  {
    "id": 2,
    "code": "ING-NOT-2019",
    "description": "Inglês Noturno 2019",
    "start_date": "2019-12-30T03:00:00.000Z",
    "end_date": "2019-12-31T03:00:00.000Z",
    "period": "Noturno",
    "language": "Inglês",
    "status": false,
    "user_id": 1,
    "created_at": "2019-12-30 10:04:47",
    "updated_at": "2020-01-05 16:08:00",
    "language_substring": "US",
    "quiz": [
      {
        "id": 1,
        "class_id": 2,
        "book_unit_id": 1,
        "book_id": 1,
        "start_date": "2020-01-03T03:00:00.000Z",
        "end_date": "2020-01-15T03:00:00.000Z",
        "book_unit_sequence": 1,
        "status": false,
        "user_id": 1,
        "created_at": "2019-12-27T11:11:21.000Z",
        "updated_at": "2019-12-30T17:54:12.000Z",
        "unit": 1,
        "sequence": 1,
        "description": "UNIT_01_GRAMMAR",
        "qt_question": 5,
        "miniature": null
      },
      {
        "id": 2,
        "class_id": 2,
        "book_unit_id": 2,
        "book_id": 1,
        "start_date": "2020-01-15T03:00:00.000Z",
        "end_date": "2020-01-31T03:00:00.000Z",
        "book_unit_sequence": 2,
        "status": false,
        "user_id": 1,
        "created_at": "2019-12-27T11:11:39.000Z",
        "updated_at": "2019-12-27T11:11:39.000Z",
        "unit": 1,
        "sequence": 2,
        "description": "UNIT_01_VOCABULARY",
        "qt_question": 5,
        "miniature": null
      },
      {
        "id": 3,
        "class_id": 2,
        "book_unit_id": 3,
        "book_id": 1,
        "start_date": "2020-01-31T03:00:00.000Z",
        "end_date": null,
        "book_unit_sequence": 1,
        "status": false,
        "user_id": 1,
        "created_at": "2019-12-27T11:11:46.000Z",
        "updated_at": "2019-12-27T11:11:46.000Z",
        "unit": 2,
        "sequence": 1,
        "description": "UNIT_02_GRAMMAR",
        "qt_question": 5,
        "miniature": null
      }
    ]
  }
]

But when i try to acess the property with: console.log(idioma[i].quiz[0] i receive undefined , but the console.log() shows that i have this property quiz and is not undefined , why this is happening?

I put a return after the console.log(idioma[i].quiz[0]) to prevent that is not subscribing but i have the same result; and

I put one console.log(i) and i have the value 0

@Edit

the console.log(idioma) without stringify:

[
  Class {
    __setters__: [
      '$attributes',
      '$persisted',
      'primaryKeyValue',
      '$originalAttributes',
      '$relations',
      '$sideLoaded',
      '$parent',
      '$frozen',
      '$visible',
      '$hidden'
    ],
    '$attributes': {
      id: 2,
      code: 'ING-NOT-2019',
      description: 'Inglês Noturno 2019',
      start_date: 2019-12-30T03:00:00.000Z,
      end_date: 2019-12-31T03:00:00.000Z,
      period: 'Noturno',
      language: 'Inglês',
      status: false,
      user_id: 1,
      created_at: 2019-12-30T13:04:47.000Z,
      updated_at: 2020-01-05T19:08:00.000Z,
      language_substring: 'US',
      quiz: [Array]
    },
    '$persisted': true,
    '$originalAttributes': {
      id: 2,
      code: 'ING-NOT-2019',
      description: 'Inglês Noturno 2019',
      start_date: 2019-12-30T03:00:00.000Z,
      end_date: 2019-12-31T03:00:00.000Z,
      period: 'Noturno',
      language: 'Inglês',
      status: false,
      user_id: 1,
      created_at: 2019-12-30T13:04:47.000Z,
      updated_at: 2020-01-05T19:08:00.000Z,
      language_substring: 'US'
    },
    '$relations': {},
    '$sideLoaded': {},
    '$parent': null,
    '$frozen': false,
    '$visible': undefined,
    '$hidden': undefined
  }
]

Answer 1

I investigated throughout the Adonisjs framework source code and found this on the BaseModel class definition. It returns a proxy , and inside the proxy, he can trap the get and the set of the attributes and do many things that you don't need necessarily to know to use the framework.

My advice is to avoid this:

idioma[i].quiz = livrosUnidadesGerarQuiz

This way you are triggering the set trap of the BaseModel and doing things that you don't needed.

Try to keep things separately, like this:

const idiomas = [];

...

const quiz = await this.getLivrosUnidadesGerarQuiz(idsClassesEstudante[i], idBookClasseEstudante[0], qtdQuizGerar);
const idioma = await this.getDadosClasseIdiomaEstudante(idsClassesEstudante[i])'
idiomas.push({ quiz, idioma });

...

This way you won't have accessor or serialization problems related to it, and you know that always idiomas[i].idioma is the model class.