Removing empty object keys in an array of objects

Question

I'm trying to create an array that sort of summarises another array. I've already received some really good ideas here, all of them are working, but all of them generate another obstacle that I, again, can't seem to solve.

Based on @kooiinc's answer, my current code looks like this:

var grants = [
    { id: "p_1", location: "loc_1", type: "A", funds: "5000" },
    { id: "p_2", location: "loc_2", type: "B", funds: "2000" },
    { id: "p_3", location: "loc_3", type: "C", funds:  "500" },
    { id: "p_2", location: "_ibid", type: "D", funds: "1000" },
    { id: "p_2", location: "_ibid", type: "E", funds: "3000" }
];
var projects = [];
grants.map(
function (v) {
    if (!(v.id in this)) {
        this[v.id] = v;
        projects.push(v);
    } else {
        var current = this[v.id];
        current.type = [v.type].concat(current.type);
        current.funds = [v.funds].concat(current.funds);
    }
}, {});

... which gives the following desired result (type and funds joined into sub-arrays, the rest are pushed unchanged):

[
    { "id": "p_1", "location": "loc_1", "type": "A", "funds": "5000" },
    { "id": "p_2", "location": "loc_2", "type": ["E","D","B"], "funds": ["3000","1000","2000"] },
    { "id": "p_3", "location": "loc_3", "type": "C", "funds": "500" }
]

However, if some of the objects have some undefined key values, the result will have nulls in the arrays. For example like this (look at the type array):

[
    { "id": "p_1", "location": "loc_1", "type": "A", "funds": "5000" },
    { "id": "p_2", "location": "loc_2", "type": ["E",null,null], "funds": ["3000","1000","2000"] },
    { "id": "p_3", "location": "loc_3", "type": "C", "funds": "500" }
]

(Here's a fiddle with the same thing.)

I've tried to find a quick way of removing these afterwards (like here or here) but for some reason none of the usual methods (of recursively removing all keys that are undefined/null) seem to work, regardless of where I put them in my code. They don't give errors, they just won't remove anything.

Is it perhaps possible to already exclude the undefined keys in the mapping somehow?

Update: So some of the object keys won't have any values, just [null,null,null] whilst others will have a few but not all like ["E",null,null]. The idea is to remove all the null items and if there's nothing left then remove the object key as well.

KooiInc · Accepted Answer · 2015-09-27 15:48:02Z

2

Try it this way:

grants.map(
 function (v) {
    if (!(v.id in this)) {
        // => initialize if empty
        v.type = v.type || [];
        v.funds = v.funds || [];
        this[v.id] = v;
        projects.push(v);
    } else {
        var current = this[v.id];
        current.type = v.type ? [v.type].concat(current.type) : current.type;
        current.funds = v.funds ? [v.funds].concat(current.funds) : current.funds;
    }
 }, {});

Now empty values will not show up in the result.

edited Sep 27, 2015 at 15:48

answered Sep 27, 2015 at 10:28

KooiInc

124k32 gold badges145 silver badges181 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

tmrk Over a year ago

Yep, I thought of this too but this doesn't seem to remove all the nulls, see here: jsfiddle.net/eebgasw6/1

KooiInc Over a year ago

I see, there is a pretty simple solution. See edited answer

Nina Scholz · Accepted Answer · 2015-09-27 11:35:12Z

0

I think you can test the occurrence of both type and funds properties and only if exist, then insert or update the element.

a.type && a.funds && ...

var grants = [
        { id: "p_1", location: "loc_1", type: "A", funds: "5000" },
        { id: "p_2", location: "loc_2", funds: "2000" },
        { id: "p_3", location: "loc_3", type: "C", funds: "500" },
        { id: "p_2", location: "_ibid", funds: "1000" },
        { id: "p_2", location: "_ibid", type: "E", funds: "3000" }
    ],
    project = [];

grants.forEach(function (a) {
    a.type && a.funds && !project.some(function (b, i) {
        if (a.id === b.id) {
            project[i].type.push(a.type);
            project[i].funds.push(a.funds);
            return true;
        }
    }) && project.push({ id: a.id, location: a.location, type: [a.type], funds: [a.funds] });
});
document.write('<pre>' + JSON.stringify(project, 0, 4) + '</pre>');

answered Sep 27, 2015 at 11:35

Nina Scholz

388k26 gold badges367 silver badges417 bronze badges

1 Comment

tmrk Over a year ago

The problem with this would be that I lose the ability to join the ones I want to join (type and funds in the example).

Collectives™ on Stack Overflow

Removing empty object keys in an array of objects

2 Answers 2

2 Comments

1 Comment

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Linked

Related