Filter array of object inside array of object

Question

I am trying to filter this json.

here is the json

const json = {
  address: "fdqn",
  pDet: [
    {
      pNam: "pnam1",
      pMem: [
        {
          mIP: "1234",  // search this string '1234'
          gp: "gp1"
        }, {
          mIP: "567", 
          gp: "gp2"
        }, {
          mIP: "890", 
          gp: "gp3"
        }
      ]
    },
    {
      pNam: "pnam1",
      pMem: [
        {
          mIP: "4567", 
          gp: "gp5"
        }, {
          mIP: "5674", 
          gp: "gp7"
        }
      ]
    }
  ]
}

I need to filter with mIP = "1234" and the final output should be.

const json = {
    address: "fdqn",
    pDet: [
      {
        pNam: "pnam1",
        pMem: [
          {
            mIP: "1234", 
            gp: "gp1"
          }
        ]
      }
    ]
  }

i tried with filter and some but seems i need to iterate inside the filter. any input will be appreciated

Your 'json' is not JSON. It's a JavaScript object. If you tried to solve this with code, you should include the code so someone can help. — jarmod
– jarmod, Commented Nov 7, 2022 at 21:51

k.tten · Accepted Answer · 2022-11-07 21:57:18Z

3

Utilizing flatMap to emulate the behavior of filter_map in other languages, we could achieve the result like this:

const json = {address:"fdqn",pDet:[{pNam:"pnam1",pMem:[{mIP:"1234",gp:"gp1"},{mIP:"567",gp:"gp2"},{mIP:"890",gp:"gp3"}]},{pNam:"pnam1",pMem:[{mIP:"4567",gp:"gp5"},{mIP:"5674",gp:"gp7"}]}]};

const search = "1234";

const result = {
    address: json.address,
    // check if there is any match in this pMem
    pDet: json.pDet.flatMap(({ pMem }) => pMem.some(({ mIP }) => mIP === search)
        ? [pMem.filter(({ mIP }) => mIP === search)] // if there is, return filtered array
        : [] // otherwise, return nothing
    ),
};

console.log(result);

answered Nov 7, 2022 at 21:57

k.tten

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1 Comment

Scott Sauyet Over a year ago

Although I like this overall (and upvoted), note that because the filter callback and the map callback both iterated through the input, and some of the advantages of filterMap are missing. I noticed this when I tried the problem with my simple, const filterMap = (f, m) => (xs) => xs .flatMap (x => f (x) ? [m (x)] : []). I will try to write an answer with an alternative.

Ludolfyn · Accepted Answer · 2022-11-07 22:22:15Z

1

You could use array.reduce() and array.filter() like this.

const json = { address: "fdqn", pDet: [{ pNam: "pnam1", pMem: [{ mIP: "1234", gp: "gp1" }, { mIP: "567", gp: "gp2" }, { mIP: "890", gp: "gp3" }] }, { pNam: "pnam1", pMem: [{ mIP: "4567", gp: "gp5" }, { mIP: "5674", gp: "gp7" }] } ] }

const newJSON = {
    address: json.address,
    pDet: json.pDet.reduce((newArr, obj) => {
        const pMem = obj.pMem.filter(obj2 => obj2.mIP === '1234')
        if (pMem.length) newArr.push({
            pNam: obj.pNam,
            pMem
        })
        return newArr
    }, [])
}

console.log(newJSON)

In a function it could look like this:

const json = { address: "fdqn", pDet: [{ pNam: "pnam1", pMem: [{ mIP: "1234", gp: "gp1" }, { mIP: "567", gp: "gp2" }, { mIP: "890", gp: "gp3" }] }, { pNam: "pnam1", pMem: [{ mIP: "4567", gp: "gp5" }, { mIP: "5674", gp: "gp7" }] } ] }

function filterArray(jsonObj, searchStr) {
    return {
        address: json.address,
        pDet: json.pDet.reduce((newArr, obj) => {
            const pMem = obj.pMem.filter(obj2 => obj2.mIP === search)
            if (pMem.length) newArr.push({
                pNam: obj.pNam,
                pMem
            })
            return newArr
        }, [])
    }
}

const newJSON = filterArray(json, '1234')

console.log( newJSON )

edited Nov 7, 2022 at 22:22

answered Nov 7, 2022 at 22:09

Ludolfyn

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1 Comment

Scott Sauyet Over a year ago

See my answer for a similar, but somewhat more generic approach.

Scott Sauyet · Accepted Answer · 2022-11-07 22:55:11Z

Similar to the technique in the answer from @caTS, although a little more generic, I used a filterMap. In my case, I grabbed a reusable function I have handy. It looks like this:

const filterMap = (f, m) => (xs) => xs .flatMap (x => f (x) ? [m (x)] : [])

const searchMIP = ({pDet, ...rest}, query) => ({
  ...rest,
  pDet: filterMap (
    ({pMem}) => pMem .some (({mIP}) => mIP == query),
    ({pMem, ...rest}) => ({...rest, pMem: pMem .filter (({mIP}) => mIP == query)})
  ) (pDet)
})

const obj = {address: "fdqn", pDet: [{pNam: "pnam1", pMem: [{mIP: "1234", gp: "gp1"}, {mIP: "567", gp: "gp2"}, {mIP: "890", gp: "gp3"}]}, {pNam: "pnam1", pMem: [{mIP: "4567", gp: "gp5"}, {mIP: "5674", gp: "gp7"}]}]}

console .log (searchMIP (obj, '1234'))

But I wasn't really happy with that, as one of the usual advantages of filterMap is that it only scans the list once. But here, we do it in the filter section, using some and again in the map section using filter.

So here's a slightly different approach, still using flatMap to do something similar, but filtering only once and using the length of the result to decide whether we're keeping the object at all:

const searchMIP = ({pDet, ...rest}, query) => ({
  ...rest,
  pDet: pDet .flatMap (
    ({pMem, kids = pMem .filter (({mIP}) => mIP == query), ...rest}) => kids .length ? [({
      ...rest, 
      pMem: pMem .filter (({mIP}) => mIP == query)
    })] : [] 
  )
})

const obj = {address: "fdqn", pDet: [{pNam: "pnam1", pMem: [{mIP: "1234", gp: "gp1"}, {mIP: "567", gp: "gp2"}, {mIP: "890", gp: "gp3"}]}, {pNam: "pnam1", pMem: [{mIP: "4567", gp: "gp5"}, {mIP: "5674", gp: "gp7"}]}]}

console .log (searchMIP (obj, '1234'))

.as-console-wrapper {max-height: 100% !important; top: 0}

This is more similar to the answer from user @Ludolfyn, but without the mutable accumulator, and again, slightly more generic.

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