How to create multiple arrays by looping through an array of multiple objects

Question

usually I refrain from asking questions but I can't really find a question similar to mine out here.

I have 2 vars, one (var subjects) for items, characters and places, the other (var books) for books, let's say Harry Potter.

{ id: 1, name: "Sorcerer's Stone", total: "333", date: "2000", set_no: ["1", "2", "IT1", "IT2", "PL1", "PL2"] },
{ id: 2, name: "Secret Chamber", total: "333", date: "2001", set_no: ["1", "2", "6", "IT1", "IT3", "PL1", "PL4"] },
{ id: 3, name: "Prisoner of Azkaban", total: "333", date: "2002", set_no: ["1", "2", "3",  "IT1", "IT2", "PL1", "PL3", "PL6"] }
]

var subjects = [
{ id: 1, name_id: [1,2,3], name: "Harry", code: "1" },
{ id: 2, name_id: [1,2,3], name: "Hagrid", code: "2" },
{ id: 3, name_id: [3], name: "Sirius", , code: "3" },
...
{ id: 6, name_id: [2], name: "Rat", code: "6" },
...
{ id: 30, name_id: [1,2,3], name: "Golden Snitch", code: "IT1"},
...
]

Of course the list goes on, in reality this is a file where var subjects = 1000 objects and var books = 150 objects.

I've already created the entire database for this, where I made an API call and filled in the "set_no"-array completely for every "book". However, I still have to get all of that data into var subjects, into the name_id array.

How would I do this? Of course in this example I wrote it manually. (but in reality once all data is filled in it'll be close to 15k items, then the real work begins and I refine my API so that it'll be closer to 45k items)

Why do I need this? The code I wrote is for a dropdown list where if I select a book, it'll only reveal the subjects that are relevant to that specific book. Which is what the name_id is for.

Any help would be much appreciated, Thanks in advance! :D

All this data is in the page accessible through script?

Kinglish
– Kinglish

2022-09-11 23:36:06 +00:00
Commented Sep 11, 2022 at 23:36 — Kinglish
– Kinglish, Commented Sep 11, 2022 at 23:36
It is hardcoded for now.

TCGPlaza
– TCGPlaza

2022-09-12 04:23:56 +00:00
Commented Sep 12, 2022 at 4:23 — TCGPlaza
– TCGPlaza, Commented Sep 12, 2022 at 4:23

Nick · Accepted Answer · 2022-09-11 23:44:58Z

3

IIUC, you can iterate the subjects array and fill in the name_id value by filtering the books array on whether the set_no includes the code from the subject; then mapping the result of filter to just return the id of the book:

const books = [
  { id: 1, name: "Sorcerer's Stone", total: "333", date: "2000", set_no: ["1", "2", "IT1", "IT2", "PL1", "PL2"] },
  { id: 2, name: "Secret Chamber", total: "333", date: "2001", set_no: ["1", "2", "6", "IT1", "IT3", "PL1", "PL4"] },
  { id: 3, name: "Prisoner of Azkaban", total: "333", date: "2002", set_no: ["1", "2", "3",  "IT1", "IT2", "PL1", "PL3", "PL6"] }
]

const subjects = [
  { id: 1, name_id: [], name: "Harry", code: "1" },
  { id: 2, name_id: [], name: "Hagrid", code: "2" },
  { id: 3, name_id: [], name: "Sirius", code: "3" },
  { id: 6, name_id: [], name: "Rat", code: "6" },
  { id: 30, name_id: [], name: "Golden Snitch", code: "IT1"},
]

subjects.forEach(s => s.name_id = books
  .filter(b => b.set_no.includes(s.code))
  .map(({ id }) => id)
)

console.log(subjects)

answered Sep 11, 2022 at 23:44

Nick

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1 Comment

TCGPlaza Over a year ago

Hi there, thank you so much! I had to make an array of strings before I could test your code out and it works like a charm! Now all that's left for me is to make some more API calls to fill in the "books.set_no" data and I'm all set. Sincerely, -Y

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