How to create nested JSON based on array of keys?

Question

Given input:

let input = [
  {
    schema: ["user", "email"],
    value: "[email protected]"
  },
  {
    schema: ["user", "name", "firstName"],
    value: "John"
  },
];

let output = {};

for (let i = 0; i < input.length; i++) {
    let data = input[i];

    for (let j = 0; j < data.schema.length; j++) {
        let s = data.schema[j];
        // How to set nested levels here ? eg: output["user"]["email"] = {};
    }
}

Expected output:

{
    "user": {
        "email": "[email protected]",
        "name": { 
            "firstName": "John" 
        }
    }
}

Here "schema" represents the nested structure in JSON for the data.

What is the approach for dynamically setting nested attributes using Javascript ?

What is data.schema? What about output["user"]["email"] = {}; isn’t working? — Sebastian Simon
– Sebastian Simon, Commented Feb 18, 2018 at 11:58
@Xufox : I cannot use output["user"]["email"] since "user" and "email" will be dynamic. — Sudhir Shrestha
– Sudhir Shrestha, Commented Feb 18, 2018 at 12:00
Okay, then just replace "user" and "email" with the variables containing the dynamic strings. See Using a variable for a key in a JavaScript object literal. — Sebastian Simon
– Sebastian Simon, Commented Feb 18, 2018 at 12:07
It is represented as array eg: ["user", "email"] so I will need to loop to set it. Please refer to the example, I have updated it. — Sudhir Shrestha
– Sudhir Shrestha, Commented Feb 18, 2018 at 12:11

trincot · Accepted Answer · 2018-02-18 12:23:28Z

2

You could use reduce to "deepen" the output object until the level where the property/value needs to be set:

const input = [{schema: ["user", "email"],value: "[email protected]"},{schema: ["user", "name", "firstName"],value: "John"},];
const output = {};

for (const obj of input) {
    obj.schema.slice(0, -1).reduce(
        (acc, lvl) => acc[lvl] || (acc[lvl] = {}), 
        output
    )[obj.schema.slice(-1)[0]] = obj.value;
}

console.log(output);

This way it also works if the schema array has more than 2 values.

edited Feb 18, 2018 at 12:23

answered Feb 18, 2018 at 12:15

trincot

357k38 gold badges282 silver badges338 bronze badges

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

3 Comments

Ele Over a year ago

The OP has changed the question's body!

trincot Over a year ago

Thanks for letting me know. Adapted the input in my answer accordingly.

Sudhir Shrestha Over a year ago

Works flawlessly, Thank you :)

Collectives™ on Stack Overflow

How to create nested JSON based on array of keys?

1 Answer 1

3 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

3 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related