How to generate array of object from object

Question

I have an object like this:

{
   name: 'ABC',
   age: 12,
   timing: '2021-12-30T11:12:34.033Z'
}

I want to make array of object of each key of above object like this:

[
   {
      fieldName: 'name',
      dataType: 'string'
   },
   {
      fieldName: 'age',
      dataType: 'number'
   },
   {
      fieldName: 'timing',
      dataType: 'date'
   }
]

I tried this:

let op = Object.entries(data).map(([key, value]) => ({
            fieldName: key,
            dataType: typeof value
        }));

but getting dataType: 'object' for date column but not able to achieve it. Is there any solution? Thanks in advance.

@evolutionxbox yah it's working with it. but not able to do it for dataType key, because it is not working for date type — techguy
– techguy, Commented Jan 27, 2022 at 8:41
Declare your Object like this { fieldName: key, dataType: typeof value} — SaschaLeh
– SaschaLeh, Commented Jan 27, 2022 at 8:47
@SaschaLeh I did the same thing, but I got result as "object" for date column — techguy
– techguy, Commented Jan 27, 2022 at 8:49
As a eager as I am too to close this question, I'm voting to re-open citing OPs last comment. There is a special case where the string date has to be used if the value of the property is a valid time stamp. — Barremian
– Barremian, Commented Jan 27, 2022 at 8:51

Rahul Sharma · Accepted Answer · 2022-01-27 09:15:13Z

1

You can use date parse to check is a valid date or not.

const input = {
  name: 'ABC',
  age: 12,
  timing: '2021-12-30T11:12:34.033Z'
};

const output = Object.entries(input).map(([key, value]) => ({
  fieldName: key,
  dataType: typeof value === 'string' && !isNaN(Date.parse(value)) ?  'date':typeof value
}));

console.log(output);

edited Jan 27, 2022 at 9:15

answered Jan 27, 2022 at 9:01

Rahul Sharma

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1 Comment

techguy Over a year ago

fieldName should be the object key, not it's value ;(

Barremian · Accepted Answer · 2022-01-27 09:16:15Z

0

You could use Object#entries with Array#map and typeof to the get the type of the value. For the case where 'date' must be used for valid time stamps, you could use Date.parse() method with Number#isNaN.

Try the following

const input = {
  name: 'ABC',
  age: 12,
  timing: '2021-12-30T11:12:34.033Z'
};

const output = Object.entries(input).map(([key, value]) => ({
  fieldName: key,
  dataType: typeof value !== 'string' || isNaN(Date.parse(value)) ? typeof value : 'date'
}));

console.log(output);

.as-console-wrapper { max-height: 100% !important; top: 0; }

Edit: Replace Object#values with Object#entries.

Edit 2: Add typeof value !== 'string' for dataType condition. Borrowed from @RahulSharma's answer.

edited Jan 27, 2022 at 9:16

answered Jan 27, 2022 at 8:52

Barremian

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8 Comments

techguy Over a year ago

getting error: Argument of type 'unknown' is not assignable to parameter of type 'string'

Barremian Over a year ago

@techguy: Update the question with your attempt. Obviously there is an error in the types you're using.

techguy Over a year ago

now it's not working with numbers, it showing 'date' for number columns as well

techguy Over a year ago

for age column also it showing 'date'

Barremian Over a year ago

@techguy: Please see here for the unknown error. TL;DR: Try to define a type for the input. If you get the "Type 'number' is not assignable to type 'string'" error for Date.parse(), include a type check for 'string' as shown by @RahulSharma in his answer.

|

Cuong Vu · Accepted Answer · 2022-01-27 09:27:47Z

Your solution looks fine, you just need to distinguish between normal string and a valid date string.

For this, I would recommend using dayjs package.

import dayjs from "dayjs";

const input = {
  name: "ABC",
  age: 12,
  timing: "2021-12-30T11:12:34.033Z"
};

const output = Object.entries(input).map(([key, value]) => {
  return {
    fieldName: key,
    dataType:
      typeof value === "string"
        ? dayjs(value).isValid()
          ? "date"
          : "string"
        : typeof value
  };
});

console.log("output", output);

CodeSandbox

If you want to reinvent the wheel and write a date checking function yourself, then take a look here for a few suggestions.

Phong Cao · Accepted Answer · 2022-01-27 09:46:20Z

0

Object.entries(a).map(([key, value]) => (
{
    fieldName: key,
    dataType: isNaN(value) && !isNaN(Date.parse(value)) ? 'date' : typeof(value) 
}))

But be careful with this as it will return for invalid dates in February, rg: 2013-02-31

With the date checking, you may should use some libraries such as Momentjs, . .

answered Jan 27, 2022 at 9:46

Phong Cao

333 bronze badges

Comments

Kien Nguyen · Accepted Answer · 2022-02-21 02:36:29Z

0

You can use Object.keys() and Array.prototype.map():

const ip = {
  name: 'ABC',
  age: 12,
  timing: '2021-12-30T11:12:34.033Z'
};

const op = Object.keys(ip).map((key) => ({
  fieldName: key,
  dataType: typeof ip[key] === 'string' && !isNaN(Date.parse(ip[key])) ? 'date' : typeof ip[key]
}));

console.log(op);

edited Feb 21, 2022 at 2:36

answered Jan 27, 2022 at 9:17

Kien Nguyen

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