javascript - 异步/等待功能不等待

Question

在这里，我正在尝试创建一个使用 MVC 模式从数据库中检索一些数据的函数。

看法

getQuestionsData (treatmentId) {

  console.log(1)

  controller.getTreatmentQuestions(treatmentId)
    .then(questions => {

      console.log(10)

      this.questions = questions   // variable is updated
    })
},

控制器

getTreatmentQuestions: async (treatmentTypeId) => {

  console.log(2)

  // first data fetch from db
  const questions = await model.getQuestion(treatmentTypeId)

  console.log(3)

  // iterate over each result record
  questions.map(async question => {

    console.log(4)

    if (question.answerType === 'select') {

      console.log(5)

      // second data fetch from db
      const answerWithChoices = await model.getQuestionChoices(question.id)

      console.log(9)

      // update question object with fetched data
      question = Object.assign({}, question, {
        choices: answerWithChoices.choices
      })
    }

    return question
  })

  return questions
}

模型

static async getQuestionChoices (questionId) {
  console.log(6)
  const answers = await db.choiceAnswers
    .where('questionId').equals(intId)
    .with({
      selectChoices: 'choiceAnswersChoices'
    })

  console.log(7)

  return answers.map(answer => {

    console.log(8)

    answer.choices = answer.selectChoices

    return answer
  })
}

我确实希望在控制台中读取此序列中的数字：1、2、3、4、5、6、7、8、9、10。相反，控制台中打印的序列是：1、2、3、4， 5、6、10、7、8、9。

这意味着模型的函数“getQuestionChoices”不等待返回语句。

我怎样才能解决这个问题？

谢谢

标签： javascriptasync-awaitdexie

Answer 1

这：

 questions.map(async question => {

    console.log(4)

    if (question.answerType === 'select') {

      console.log(5)

      // second data fetch from db
      const answerWithChoices = await model.getQuestionChoices(question.id)

      console.log(9)

      // update question object with fetched data
      question = Object.assign({}, question, {
        choices: answerWithChoices.choices
      })
    }

    return question
  })

返回一个 promise 数组，并且结果没有分配到任何地方

修复：

 questions = await Promise.all(questions.map(async question => {

    console.log(4)

    if (question.answerType === 'select') {

      console.log(5)

      // second data fetch from db
      const answerWithChoices = await model.getQuestionChoices(question.id)

      console.log(9)

      // update question object with fetched data
      question = Object.assign({}, question, {
        choices: answerWithChoices.choices
      })
    }

    return question
  }))