Find Object in Array of Objects based off key using Array.find()

Question

So I have an array of names:

const names = ['student1', 'student2', 'student3']

and I have an array of attendance objects:

const attendance = [
  {student1: ['On Time', 'Late']},
  {student2: ['Late', 'Late']},
  {student3: ['On Time', 'Excused']},
]

I wanted to find the student object in the attendance array based off the names from the names array.

So currently I have:

names.forEach(person => {
  function attendanceData(p) {
     return Object.keys(attendance).toString() == p.toString()
  }
  console.log(attendance.find(attendanceData(person)))
})

However, this gives me an error saying:

Uncaught (in promise) TypeError: false is not a function

The next stack says "at Array.find()"

I'm wondering how I'm not using this correctly and if there was a better way to do this, what should I do?

The result of Object.keys(attendance).toString() will be "0,1,2" — Phil
– Phil, Commented May 28, 2020 at 22:41
Your data structure does not lend itself to being consumed very well. A better structure for attendance would be {name: 'student', attendance: [...]}. That way you don't need to guess at random keys — Phil
– Phil, Commented May 28, 2020 at 22:43

richytong · Accepted Answer · 2023-09-17 10:09:58Z

2

I believe this is what you want. Your data is structured a little strangely though, so I would like to know on a larger scale what you want this code to do.

const findStudentAttendance = (att, studentName) => {
  return att.find(obj => Object.keys(obj)[0] === studentName)
}

names.forEach(name => {
  console.log(
    findStudentAttendance(attendance, name)
  )
}) /* =>
{ student1: [ 'On Time', 'Late' ] }
{ student2: [ 'Late', 'Late' ] }
{ student3: [ 'On Time', 'Excused' ] }
*/

edited Sep 17, 2023 at 10:09

answered May 28, 2020 at 22:41

richytong

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1 Comment

reid poynter Over a year ago

This worked wonderfully. Thank you very much. Also to answer your question, I'm just building a little app that builds a pdf of student grades and attendance

DMITRYTISHKIN · Accepted Answer · 2020-05-29 09:39:04Z

0

try it

let result = attendance.filter(obj => names.includes(Object.keys(obj)[0]))
console.log(result)

Use array's method "filter" for getting items. You need get keys of object and take first key. And then you'll can check presence in names array, via array's method "includes"

more information about this methods here:

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/includes

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/Filter

edited May 29, 2020 at 9:39

answered May 28, 2020 at 22:40

DMITRYTISHKIN

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1 Comment

SherylHohman Over a year ago

While this code may resolve the OP's issue, it is best to include an explanation as to how your code addresses the OP's issue. In this way, future visitors can learn from your post, and apply it to their own code. SO is not a coding service, but a resource for knowledge. Also, high quality, complete answers are more likely to be upvoted. These features, along with the requirement that all posts are self-contained, are some of the strengths of SO as a platform, that differentiates it from forums. You can edit to add additional info &/or to supplement your explanations with source documentation.

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