Group by/order by On JSON data using javascript/jquery

Question

I have a JSON data and I need to do something like group by and i asked this question before here but i am not getting any satisfied answer so this time i would like to expl

Answer 1

Use first class functions to create generic group by key reducers and a sorters. I will take the reducer from a previous answer of mine. That way you can sort and group by any key you like, in a similar way that you would do in SQL.

const groupBy = key => (result,current) => {
  const item = Object.assign({},current);
  if (typeof result[current[key]] == 'undefined'){
    result[current[key]] = [item];
  }else{
    result[current[key]].push(item);
  }
  return result;
};

const stringSortBy = key => (a,b) => {
   const sa = a[key];
   const sb = b[key];
   return sa < sb ? -1 : +(sa > sb);
};

const myObject = {
    "Apps": [
        {
            "Name": "app1",
            "id": "1",
            "groups": [
                {
                    "id": "1",
                    "name": "test group 1",
                    "category": "clinical note",
                    "author": "RRP"
                }, {
                    "id": "2",
                    "name": "test group 2",
                    "category": "clinical image",
                    "author": "LKP"
                }, {
                    "id": "3",
                    "name": "test group 3",
                    "category": "clinical document",
                    "author": "RRP"
                }, {
                    "id": "4",
                    "name": "test group 4",
                    "category": "clinical note",
                    "author": "John"
                }
            ]
        }
    ]
}

const categories = myObject.Apps[0].groups.reduce(groupBy('category'),{});
console.log(categories);
const sorted = myObject.Apps[0].groups.sort(stringSortBy('author'));
console.log(sorted);

Answer 2

You can do that easily with Underscore.js:

_.chain(myObject.Apps[0].groups).sortBy("author").groupBy("author").value();

Outputs a JSON object:

{
 "John":[{"id":"4","name":"test group 4","category":"clinical note","author":"John"}],
 "LKP":[{"id":"2","name":"test group 2","category":"clinical image","author":"LKP"}],
 "RRP":[{"id":"1","name":"test group 1","category":"clinical note","author":"RRP"},{"id":"3","name":"test group 3","category":"clinical document","author":"RRP"}]
}

Answer 3

There is no built-in "group by" or "order by" in Javascript for this scenario. You're going to have to do this manually. Something like this might help:

var groups = myObject.Apps[0].groups;
var authors = {};
var authorNames = [];

for(var i = 0; i < groups.length; i++) {
    var group = groups[i];    

    if(typeof authors[group.author] === "undefined") {
        authors[group.author] = [];
        authorNames.push(group.author);
        authorNames.sort();
    }

    authors[group.author].push({
        id: group.id,
        name: group.name,
        category: group.category
    });       
}

Usually in associative arrays you don't really care about the order of the keys and while iterating the order is usually not guaranteed. What I'm doing here is maintaining a separate array of names in sorted order. I can then iterate over that array and use those values to grab the associated object out of the associative array.

Check out the fiddle.