Remove duplicates from multi-level array of objects

Question

I have this array of objects and I am wanting to filter out where myDatas.items.flaggedItem is not null and at the same time remove the duplicates where myDatas.items.id are the same. So in this instance I would only expect 2 to be returned

"myDatas":[
  {
    "id": "id1",
    "items":[
       {
         "id": "idOne",
         "flaggedItem": null,
       },
       {
         "id": "idTwo",
         "flaggedItem": 1,
       },
   },
   {
     "id": "id2",
     "items":[
       {
         "id": "idTwo",
         "flaggedItem": 1,
       },
       {
         "id": "idOne",
         "flaggedItem": 2,
       },
   }
]

I have this, but unable to find a good way to remove the duplicates. This accomplishes the first part where I am pulling only items where myDatas.items.flaggedItem is not null, but does not remove the duplicates.

  let test1 = myDatas
    ?.map(myData => {
      let test2 = myData.items?.filter(
        items => items.flaggedItem || items.flaggedItem === 0
      );
      return { ...myData, items: test2 };
    });

You're going to have to concatenate the items arrays together to deduplicate it easily... — Heretic Monkey
– Heretic Monkey, Commented Aug 21, 2023 at 18:30
Does this answer your question? Remove duplicates from NESTED array of objects — Heretic Monkey
– Heretic Monkey, Commented Aug 21, 2023 at 18:32

technophyle · Accepted Answer · 2023-08-21 18:39:36Z

0

Easiest way to filter out the duplicate data is by keeping a duplicates map:

const myData = [
  {
    "id": "id1",
    "items": [
      {
        "id": "idOne",
        "flaggedItem": null,
      },
      {
        "id": "idTwo",
        "flaggedItem": 1,
      },
    ],
  },
  {
    "id": "id2",
    "items": [
      {
        "id": "idTwo",
        "flaggedItem": 1,
      },
      {
        "id": "idOne",
        "flaggedItem": 2,
      },
    ],
  },
];

const duplicates = {};

const dedupedData = myData.map((element) => {
  const items = element.items.filter((item) => {
    if (!item.flaggedItem && item.flaggedItem !== 0) return false;

    if (duplicates[item.id]) return false;
    duplicates[item.id] = true;

    return true;
  });

  return {
    ...element,
    items,
  };
});

console.log(dedupedData);

answered Aug 21, 2023 at 18:39

technophyle

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