How to implement sorting on nested array with keys and sorting order

Question

I'm trying to implement multiple sorting on nested array based on keys and sort order.

I'm able to sort an array based on the key and order

I've done the following code for sorting on array,

return array.sort((a, b) => {
      let i = 0, result = 0;
      while (i < sortBy.length && result === 0) {
        if (typeof a[sortBy[i].prop] == "string") {
          result = sortBy[i].direction * (a[sortBy[i].prop].toString() < b[sortBy[i].prop].toString() ? -1 : (a[sortBy[i].prop].toString() > b[sortBy[i].prop].toString() ? 1 : 0));
        } else {
          result = sortBy[i].direction * (a[sortBy[i].prop] < b[sortBy[i].prop] ? -1 : (a[sortBy[i].prop] > b[sortBy[i].prop] ? 1 : 0));
        }
        i++;
      }
      return result;
    });

My Input Data is given below,

array = [{ x: [{ d: 4 }, { d: 2 }, { d: 3 }, { d: 1 }], b: 'v' }, { x: [{ d: 8 }, { d: 7 }, { d: 5 }, { d: 6 }], b: 's' }];
sortBy= [{ 'prop': 'b', 'direction': 1 }, { 'prop': 'd', 'direction': 1}];

I expected an output like below,

array = [{ x: [{ d: 5 }, { d: 6 }, { d: 7 }, { d: 8 }], b: 's' },{ x: [{ d: 1 }, { d: 2 }, { d: 3 }, { d: 4 }], b: 'v' }];

But I'm getting the below result,

array = [{ x: [{ d: 8 }, { d: 7 }, { d: 5 }, { d: 6 }], b: 's' },{ x: [{ d: 4 }, { d: 2 }, { d: 3 }, { d: 1 }], b: 'v' }];

I'm stuck on how to solve this logical problem. can anyone help me on this.

Spencer Wieczorek · Accepted Answer · 2019-06-18 08:57:00Z

You're close, what you will want to do is call your sort method on the inner arrays that have the property x. Then afterwords call it on the original array. That will sort the subarrays with the d property first, then afterword sort outer array by b.

array = [{ x: [{ d: 4 }, { d: 2 }, { d: 3 }, { d: 1 }], b: 'v' }, { x: [{ d: 8 }, { d: 7 }, { d: 5 }, { d: 6 }], b: 's' }];
sortBy= [{ 'prop': 'b', 'direction': 1 }, { 'prop': 'd', 'direction': 1}];

function sortFunc(a, b) {
  let i = 0, result = 0;
  while (i < sortBy.length && result === 0) {
    if (typeof a[sortBy[i].prop] == "string") {
      result = sortBy[i].direction * (a[sortBy[i].prop].toString() < b[sortBy[i].prop].toString() ? -1 : (a[sortBy[i].prop].toString() > b[sortBy[i].prop].toString() ? 1 : 0));
    } else {
      result = sortBy[i].direction * (a[sortBy[i].prop] < b[sortBy[i].prop] ? -1 : (a[sortBy[i].prop] > b[sortBy[i].prop] ? 1 : 0));
    }
    i++;
  }
  return result;
}

array.forEach(arr => arr.x = arr.x.sort(sortFunc));
array = array.sort(sortFunc);
console.log(array);

relief.melone · Accepted Answer · 2019-06-18 11:08:01Z

From what I see you need to make this one recursive and call the function whenever you hit an array in your object. Take a look at this

let input = [
{ x: [{ d: 4 }, { d: 2 }, { d: 3 }, { d: 1 }], b: 'v' }, 
{ x: [{ d: 8 }, { d: 7 }, { d: 5 }, { d: 6 }], b: 's' }
];

const sortingInstructions = [
  {prop: 'b', direction: 1},
  {prop: 'd', direction: 1}
];

const isArray = Obj => {
  return typeof(Obj) === 'object' && Obj.length !== undefined
}

const nestedSort = SortingArray => {
  for(let obj of SortingArray){
  	for(let key of Object.keys(obj)){
    	if(isArray(obj[key])){
        nestedSort(obj[key])
      }
    }  	
  }
  for(let instruction of sortingInstructions){

    SortingArray.sort((a,b) => {
      if(typeof(a[instruction.prop]) === 'string'){
        return instruction.direction*b[instruction.prop].localeCompare(a[instruction.prop])
      }
      if(typeof(a[instruction.prop]) === 'number'){
        return instruction.direction*(b[instruction.prop]-a[instruction.prop]);
      }
    })
  }
	
  
  return SortingArray;
}

nestedSort(input);
console.log(input);

What this does is the following.

if you hit an array in your object you call the function recursively on this array
you sort the array by all your instructions (the ones further down in your instructions beeing the dominant ones as they are used to sort the latest)
if what you are hitting is a string you use localeCompare to sort it

As this is recursive it will also run on any depth of object. So e.g.

let input = [
  { x: [{y:[{ d: 4 }, { d: 2 }, { d: 3 }, { d: 1 }]}], b: 'v' }, 
  { x: [{z:[{ d: 8 }, { d: 7 }, { d: 5 }, { d: 6 }]}], b: 's' }
]

would also work

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How to implement sorting on nested array with keys and sorting order

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How to implement sorting on nested array with keys and sorting order

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