How can i make an array of object to an an array of strings-CodePudding

I am having an api response displayed as below

{
    "children": [
        {
            "_id": "61f29cfb23ff35136c98fdcc"
        },
        {
            "_id": "61f2ab6123ff35136c996839"
        },
        {
            "_id": "61f2ad1a23ff35136c998270"
        }
    ],
    "id": "61e2e09244d6583cdfead089"
}

This is the code for the response

exports.fetchCategoryChildren = async (req,res) => {
  const category = await Category
  .find({_id: req.params.id })
  .select('children._id')
  if (!category) return res.status(400).json('No category found');
  return res.json(_.head(category));

But i want a respone like this

            [
            "_id": "61f29cfb23ff35136c98fdcc",
            "_id": "61f2ab6123ff35136c996839",
            "_id": "61f2ad1a23ff35136c998270"
           ],

Because i want to use the response in an $in operator which takes an array.

How can i achieve my desired result?

CodePudding user response：

The desired output you want is not a valid JavaScript. You can have array of objects or array of strings.

Here is a code that returns an array of the ids, so the output will be:

["61f29cfb23ff35136c98fdcc", "61f2ab6123ff35136c996839", "61f2ad1a23ff35136c998270"]

  const res = {
        "children": [
            {
                "_id": "61f29cfb23ff35136c98fdcc"
            },
            {
                "_id": "61f2ab6123ff35136c996839"
            },
            {
                "_id": "61f2ad1a23ff35136c998270"
            }
        ],
        "id": "61e2e09244d6583cdfead089"
    }

const mapped = res.children.map(child => child._id)

console.log(mapped)
// ["61f29cfb23ff35136c98fdcc", "61f2ab6123ff35136c996839", "61f2ad1a23ff35136c998270"]