Tutorial :How to order a JSON object by two keys?



Question:

I have a JSON object that I want to sort by one key first, then by a second key similar to ordering by two columns in SQL. Here is a sample of the JSON I would have:

{     "GROUPID":3169675,     "LASTNAME":"Chantry"  }  

I would like to order all the results by the GROUPID and then by LASTNAME. I've used the JSON sort function to sort by one key but not multiple.

Any help would be great.


Solution:1

Assuming you have an array of objects:

var data = [      { "GROUPID":3169675, "LASTNAME":"Chantry" },      { "GROUPID":3169612, "LASTNAME":"Doe" },      ...  ];  

You can use a custom comparator to do the sorting. To sort first by GROUPID, and then by LASTNAME, the logic to compare two objects would be:

if GROUPID of first is smaller than second      return -1;  else if GROUPID of first is larger than second      return 1;  else if LASTNAME of first is smaller than second      return -1;  else if LASTNAME of first is larger than second      return 1;  else      return 0;  

To sort the object array, use the above algorithm and call the sort method on the array. After sorting is done, data should have the elements in required sorted order.

data.sort(function(a, b) {      // compare a and b here using the above algorithm  });  

Here's another very similar question I answered recently. It's regarding sorting on multiple columns using jQuery, but you can strip out the jQuery part easily. It presents some customizable approaches which can extend to multiple columns.


Solution:2

Here is a generic way to sort an array of objects, with multiple columns:

var arr = [      { id:5, name:"Name3" },      { id:4, name:"Name1" },      { id:6, name:"Name2" },      { id:3, name:"Name2" }  ],    // generic comparison function  cmp = function(x, y){      return x > y ? 1 : x < y ? -1 : 0;   };    //sort name ascending then id descending  arr.sort(function(a, b){      //note the minus before -cmp, for descending order      return cmp(           [cmp(a.name, b.name), -cmp(a.id, b.id)],           [cmp(b.name, a.name), -cmp(b.id, a.id)]      );  });  

To add other columns to sort on, you can add other items in the array comparison.

arr.sort(function(a, b){      return cmp(           [cmp(a.name, b.name), -cmp(a.id, b.id), cmp(a.other, b.other), ...],           [cmp(b.name, a.name), -cmp(b.id, a.id), cmp(b.other, a.other), ...]      );  });  

EDIT: per @PhilipZ comment below, the array comparison in JS convert them in strings separated by comas.


Solution:3

If you are searching a more generalized approach consider using the function provided in that answer.


Note:If u also have question or solution just comment us below or mail us on toontricks1994@gmail.com
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