使用数组作为 object 键

Question

Following is my object:

let body = {
  size: 0,
  aggs: {
    colour: {
      terms: {
        size: 10000,
        field: "brand_name.keyword",
      },
    },
  },
};

and by traversing above object I make array of keys

let kys = ["aggs", "colour"]

Now I want to access my object and add new object after the colour. My question is how I can use the array kys to access colour in above object body .

I mean I want to add the following empty object:

body["aggs"]["colour"]["newkey"] = {}

But I don't want to hardcode keys define in kys.

Thanks

Answer 1

There's the array syntax for JavaScript objects:

 let body = { size: 0, aggs: { colour: { terms: { size: 10000, field: "brand_name.keyword" } } } } let kys = ["aggs", "colour"] body[kys[0]].colour2 = { terms: { size: 10000, field: "brand_name2.keyword" } } console.log(body)

Answer 2

What you need is a function similar to lodash.get , which gets a deeply nested value from a string or array of keys. For your example you could do any of the following:

const colour = _.get(body, kys);
// which is the same as:
const colour = _.get(body, ['aggs', 'colour']);
// which could also be written:
const colour = _.get(body, 'aggs.colour');

It's also fun to write your own get function, but I'll leave that as an exercise for the OP.

EDIT: There is also a lodash.set method which will set a deeply nested value. It would look something like this:

let kys = ['aggs', 'colour'];
let kys2 = kys.slice(0, -1).concat('coulor2');
_.set(body, kys2, { foo: 'bar' });
// which is the same as:
_.set(body, ['aggs', 'colour2'], { foo: 'bar' });
// which could also be written:
_.set(body, 'aggs.colour2', { foo: 'bar' });

Answer 3

If I understand correctly what you want you can just use a for loop and iterate through object.

Since Objects are passed by "copy of a reference" it is possible to modify the contents of passed object.

I wrote a small function doing that.

 let body = { size: 0, aggs: { colour: { terms: { size: 10000, field: "brand_name.keyword" } } } } let kys = ["aggs", "colour"]; function set_nested_key(obj,kys,new_object){ for(let i=0;i<kys.length; i++) { obj=obj[kys[i]];} obj[Object.keys(new_object)[0]]=new_object[Object.keys(new_object)[0]]; } set_nested_key(body,kys,{"foo":{}}); console.log(body);

Answer 4

Just to clarify the problem statement, this:

body["aggs"]["colour"]["newkey"] = {}

will result in the following body :

{
  size: 0,
  aggs: {
    colour: {
      terms: {
        size: 10000,
        field: "brand_name.keyword"
      },
      newkey: {},  // the addition
    },
  }
}

Given that you have array kys === ["aggs", "colour"] , the following will insert a property named "newkey", with value an empty object {} , into the property named "colour":

body[kys[0]][kys[1]].newkey = {}