Delete main array when nested array is empty

Question

I got the following array:

var arr = [{
    "mainId": 1,
    "parents": [{
        "parent": 1
      },
      {
        "parent": 2
      }
    ]
  },
  {
    "mainId": 2,
    "parents": [{
      "parent": 3
    }]
  }
]

I'm using this function to delete an specific parent in the parents array

var idToDelete = 2
arr.forEach(function (o) {
  o.parents = o.parents.filter(s => s.id !== idToDelete 
})

This is working fine. But when idToDelete = 3 I want to delete the complete main Item and start a function "startSomething"

So that I'm left with the following output

var arr = [{
  "mainId": 1,
  "parents": [{
      "parent": 1
    },
    {
      "parent": 2
    }
  ]
}]

How could this be implemented?

What do you mean by and start a function "startSomething" ? — Nick Parsons
– Nick Parsons, Commented Feb 1, 2020 at 9:24

Titus · Accepted Answer · 2020-02-01 09:28:15Z

1

You can map and then filter the top level array, here is an example:

var arr = [{
    "mainId": 1,
    "parents": [{
        "parent": 1
      },
      {
        "parent": 2
      }
    ]
  },
  {
    "mainId": 2,
    "parents": [{
      "parent": 3
    }]
  }
];

var idToDelete = 3;

arr = arr.map((v) => ({
    ...v,
    parents: v.parents.filter(({
      parent
    }) => parent !== idToDelete)
  }))
  .filter((v) => v.parents.length);

console.log(arr);

answered Feb 1, 2020 at 9:28

Titus

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Comments

CertainPerformance · Accepted Answer · 2020-02-01 09:25:06Z

0

Filter the parent array by whether it has a .length after mutating the children. Also make sure to use the .parent property (your objects have no .id property):

const startSomething = () => console.log('startSomething');

var arr = 
[
  {
    "mainId": 1,
    "parents": [
      {
        "parent": 1
      },
      {
        "parent": 2
      }
    ]
  },
  {
    "mainId": 2,
    "parents": [
      {
        "parent": 3
      }
    ]
  }
];

var idToDelete = 3;
arr.forEach(function (o) {
  o.parents = o.parents.filter(s => s.parent !== idToDelete)
});
const newArr = arr.filter(({ parents }) => parents.length);
console.log(newArr);
if (newArr.length !== arr.length) {
  startSomething();
}

answered Feb 1, 2020 at 9:25

CertainPerformance

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Comments

Nick Parsons · Accepted Answer · 2020-02-01 09:44:35Z

0

You can use .filter() on the array itself (to remove the main object) with .some() to return true or false depending on whether it should be deleted or not:

const arr = [{ "mainId": 1, "parents": [{ "parent": 1 }, { "parent": 2 } ] }, { "mainId": 2, "parents": [{ "parent": 3 }] } ];

const removeObj = (arr, id, cb) => {
  const res = arr.filter(({parents}) => !parents.some(({parent}) => parent === id));
  const item_removed = res.length !== arr.length;
  return (item_removed && cb(res), item_removed);
}
 
const startSomething = new_arr => console.log("Starting with arr", new_arr);
removeObj(arr, 3, startSomething);

.as-console-wrapper { max-height: 100% !important;} /* ignore */

edited Feb 1, 2020 at 9:44

answered Feb 1, 2020 at 9:25

Nick Parsons

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Comments

LukStorms · Accepted Answer · 2020-02-01 12:06:45Z

Here's a alternative method, with a function that uses findIndex to find the object in the array.

Then splices the object if it only has 1 parent.
Or splices the parent from object if it has more than 1 parent.

Example snippet:

const deleteParent = (arr, id) =>
{
     let idx = arr.findIndex(x=>x.parents.some(p=> p.parent === id));
     if (idx >= 0 && arr[idx].parents.length === 1 ) {
       let obj = arr[idx];
       // remove object from array and do something
       arr.splice(idx, 1); 
       doSomething(obj);
     }
     else if(idx >= 0){
       let obj = arr[idx];
       let parentIdx = obj.parents.findIndex(x=>x.parent==id);
       // remove parent
       obj.parents.splice( parentIdx, 1);
    }
}

function doSomething (obj) { console.log(`Deleted mainId ${obj.mainId}`) }

var arr = [
  {
    "mainId": 1,
    "parents": [
      {
        "parent": 1
      },
      {
        "parent": 2
      }
    ]
  },
  {
    "mainId": 2,
    "parents": [
      {
        "parent": 3
      }
    ]
  }
];

deleteParent(arr, 3);
console.log(JSON.stringify(arr));

deleteParent(arr, 2);
console.log(JSON.stringify(arr));

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