Javascript - sorting JSON object by a nested value

Question

Summary : there is a multilevel parent-child comment system.i.e.

Example :

comment 1
    comment 1-1
        comment 1-1-1
    comment 1-2
        comment 1-2-1
             comment 1-2-2

Here, comment 1 is parent and comment 1-1 & comment 1-2 both are child of comment 1 and so on..

Requirement :

we want to achieve the sorting of whole object based on property value.i.e. timestamp(latest comment or reply will come on the top).

JSON Object :

{
  "CommentText": "",
  "CommentCreateStamp": "2016-03-22",
  "Comments": [{
    "CommentText": "comment 1",
    "CommentCreateStamp": "2016-03-09",
    "Comments": [{
      "CommentText": "comment 1-1",
      "CommentCreateStamp": "2016-03-15",
      "Comments": [{
        "CommentText": "comment 1-1-1",
        "CommentCreateStamp": "2016-03-21",
        "Comments": null
      }]
    }]
  }],
  "Comments": [{
    "CommentText": "comment 2",
    "CommentCreateStamp": "2016-03-12",
    "Comments": [{
      "CommentText": "comment 2-1",
      "CommentCreateStamp": "2016-03-10",
      "Comments": [{
        "CommentText": "comment 2-1-1",
        "CommentCreateStamp": "2016-03-14",
        "Comments": null
      }]
    }]
  }]
}

i tried so far :

JSfiddle : https://jsfiddle.net/asceeevb/

I seen lot of questions on stackoverflow but not working as per requirement.

Any immediate help will be highly appreciable. Thanks

you can only sort on the same level, if the structure should remain. — Nina Scholz, Mar 22 '16 at 17:11
@georg, not a flat list. i want the data in sorted way according to the `CommentCreateStamp` property.the latest comments should come on the top and same with child hierarchy also. I updated the JSON object. please check now. — Rohit Jindal, Mar 23 '16 at 01:21
@NinaScholz, there is no way to sort hierarichal structure ? — Rohit Jindal, Mar 23 '16 at 04:58
Try this link hope its help you. http://stackoverflow.com/questions/13758467/how-do-i-sort-a-json-object-by-a-nested-value — Bhupesh, Mar 23 '16 at 08:13
Try this link i hope its work for you. http://stackoverflow.com/questions/13758467/how-do-i-sort-a-json-object-by-a-nested-value — Bhupesh, Mar 23 '16 at 08:14
Try this link http://stackoverflow.com/questions/13758467/how-do-i-sort-a-json-object-by-a-nested-value — Bhupesh, Mar 23 '16 at 08:15

score 2 · Accepted Answer · edited May 23 '17 at 11:46

I am not entirely sure what you are asking, but there a couple of things that seem wrong with your code:

you redefined the comments property of the object, perhaps you wanted an array?
your sorting function is supposed to return a value based on comparison of elements, not output it. See this SO question for date comparison.

Update: You were close, what you were missing were calls to sorting for the nested comments. Here is a snippet that calls sorting recursively:

var people = {
  "CommentText": "",
  "CommentCreateStamp": "",
  "Comments": [{
    "CommentText": "c1",
    "CommentCreateStamp": "2016-03-23 06:05:36",
    "Comments": [{
      "CommentText": "c2",
      "CommentCreateStamp": "2016-03-23 06:05:59",
    }],
  }, {
    "CommentText": "a1",
    "CommentCreateStamp": "2017-03-23 06:05:45",
    "Comments": [{
      "CommentText": "a2",
      "CommentCreateStamp": "2016-03-23 06:06:05",
    }, {
      "CommentText": "a3",
      "CommentCreateStamp": "2016-03-23 06:06:16",
    }, {
      "CommentText": "a4",
      "CommentCreateStamp": "2016-03-23 06:06:23",
    }],
  }],
};



function sorting(js_object, key_to_sort_by) {

  function sortByKey(a, b) {
    var x = a[key_to_sort_by];
    var y = b[key_to_sort_by];
    return ((x < y) ? 1 : ((x > y) ? -1 : 0));
  };

  js_object.sort(sortByKey);

};

function sortComments(comments) {
  
  sorting(comments, 'CommentCreateStamp');
  for (var i = 0; i < comments.length; i++)
    if (comments[i].hasOwnProperty('Comments'))
      sortComments(comments[i].Comments);

};

sortComments(people.Comments);
console.log(people.Comments);

score 1 · Answer 2 · answered Mar 22 '16 at 21:19

You could make a flat array which keeps the reference and sort it by CommentCreateStamp.

function getFlat(o) {
    this.push(o);
    Array.isArray(o.Comments) && o.Comments.forEach(getFlat.bind(this));
}

var object = { "CommentText": "", "CommentCreateStamp": "2016-03-22", "Comments": [{ "CommentText": "comment 1", "CommentCreateStamp": "2016-03-18", "Comments": [{ "CommentText": "comment 1-1", "CommentCreateStamp": "2016-03-15", "Comments": [{ "CommentText": "comment 1-1-1", "CommentCreateStamp": "2016-03-21", "Comments": null }] }] }] },
    flat = [];

getFlat.bind(flat)(object);
flat.sort(function (a, b) {
    return a.CommentCreateStamp.localeCompare(b.CommentCreateStamp);
});
document.write('<pre>' + JSON.stringify(flat, 0, 4) + '</pre>');

Thanks for the answer but i want sorted object not an flat array in same format. — Rohit Jindal, Mar 23 '16 at 04:59

score 0 · Answer 3 · answered Mar 21 '17 at 00:05

Refining the @changed answer slightly -- I find that the following works pretty well:

  export function sortObj(jsObj, sortKey,flgReverse) {
    sortKey = sortKey.split(".");
    let sk = '';
    Object.keys(sortKey).forEach(function(key,idx){
    sk += '[\'' + sortKey[key] + '\']';
    });
    function sortByKey(a, b) {
      var x = eval("a" + sk);
      var y = eval("b" + sk);
      if(flgReverse) return  ((x < y) ? -1 : ((x > y) ? 1 : 0));
      else return ((x < y) ? 1 : ((x > y) ? -1 : 0));
    };
    return jsObj.sort(sortByKey);
  };

Javascript - sorting JSON object by a nested value

3 Answers3