Separating (n) keys from array of objects into a single array with keys names

Question

I need to perform filter in the array of objects to get all the keys. Although, whenever there is a obj inside of that key, I would need to get the key name and concat with the key name from the obj, so for example:

const data = [ id: 5, name: "Something", obj: { lower: True, higher: False } ]
result = ["id", "name", "obj.lower", "obj.higher"]

I could manage to do the above code, but, if there is more objs inside the data, I would need to keep adding a if condition inside of my logic, I would like to know if there is any other way, so it doesn't matter how many objects I have inside the objects, It will concat always.
The code I used from the above mention:

const itemsArray = [
      { id: 1, item: "Item 001", obj: { name: 'Nilton001', message: "Free001", obj2: { test: "test001" } } },
      { id: 2, item: "Item 002", obj: { name: 'Nilton002', message: "Free002", obj2: { test: "test002" } } },
      { id: 3, item: "Item 003", obj: { name: 'Nilton003', message: "Free003", obj2: { test: "test003" } } },
    ];

const csvData = [    
    Object.keys(itemsArray[0]),
    ...itemsArray.map(item => Object.values(item))
].map(e => e.join(",")).join("\n")

// Separating keys
let keys = []
const allKeys = Object.entries(itemsArray[0]);
for (const data of allKeys) {
    if (typeof data[1] === "object") {
        const gettingObjKeys = Object.keys(data[1]);
        const concatingKeys = gettingObjKeys.map((key) => data[0] + "." + key);        
        keys.push(concatingKeys);
    } else {
        keys.push(data[0])
    }
}

//Flating
const flattingKeys = keys.reduce((acc, val: any) => acc.concat(val), []);

What I would like to achieve, lets suppose I have this array of object:

const data = 
[
   { id: 10, obj: {name: "Name1", obj2: {name2: "Name2", test: "Test"}}}
   ...
]

Final result = ["id", "obj.name", "obj.obj2.name2", "obj.obj2.test"]

OBS: The first obj contains all the keys I need, no need to loop through other to get KEYS.

I would like to achieve, all the keys from the first object of the array, and if there is objects inside of objects, I would like to concat the obj names (obj.obj2key1)

Your data isn;t valid js ? Please add a minimal reproducible example — 0stone0
– 0stone0, Commented Apr 28, 2022 at 14:47

Nina Scholz · Accepted Answer · 2022-04-28 18:13:21Z

3

You could map the key or the keys of the nested objects.

const
    getKeys = object => Object
        .entries(object)
        .flatMap(([k, v]) => v && typeof v === 'object'
            ? getKeys(v).map(s => `${k}.${s}`)
            : k
        ),
    getValues = object => Object
        .entries(object)
        .flatMap(([k, v]) => v && typeof v === 'object'
            ? getValues(v)
            : v
        ),
    data = { id: 1, item: "Item 001", obj: { name: 'Nilton001', message: "Free001", obj2: { test: "test001" } } },
    keys = getKeys(data),
    values = getValues(data);

console.log(keys);
console.log(values);

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

edited Apr 28, 2022 at 18:13

answered Apr 28, 2022 at 15:12

Nina Scholz

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3 Comments

Nilton Schumacher F Over a year ago

This worked better since it doesn't check if value from key is null

Nilton Schumacher F Over a year ago

Could you add a code that will do the same, although it will get the value of the items separeted by commas? [1, "Item 001", "Nilton001, "Free001]...

Nina Scholz Over a year ago

@NiltonSchumacherF, it is nearly the same without mapping prepending key.

R4ncid · Accepted Answer · 2022-04-28 14:58:06Z

2

something like this

const itemsArray = [
      { id: 1, item: "Item 001", obj: { name: 'Nilton001', message: "Free001", obj2: { test: "test001" } } },
      { id: 2, item: "Item 002", obj: { name: 'Nilton002', message: "Free002", obj2: { test: "test002" } } },
      { id: 3, item: "Item 003", obj: { name: 'Nilton003', message: "Free003", obj2: { test: "test003" } } },
    ];
    
const item = itemsArray[0];

const getAllKeys = (obj, prefix=[]) => {
 if(typeof obj !== 'object'){
   return prefix.join('.')
 }
 return Object.entries(obj).flatMap(([k, v]) => getAllKeys(v, [...prefix, k]))
}

console.log(getAllKeys(item))

answered Apr 28, 2022 at 14:58

R4ncid

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Comments

danh · Accepted Answer · 2022-04-28 15:13:28Z

0

The OP solution can be simplified by accepting a prefix param (the parent key) and a results param (defaulted to [] and passed into the recursion) to do the flattening...

let obj = { key0: 'v0', key1: { innerKey0: 'innerV0', innerInner: { deeplyNested: 'v' } }, key2: { anotherInnerKey: 'innerV' } }

function recursiveKeys(prefix, obj, result=[]) {
  let keys = Object.keys(obj);
  keys.forEach(key => {
    if (typeof obj[key] === 'object')
      recursiveKeys(key, obj[key], result);
    else
      result.push(`${prefix}.${key}`)
  });
  return result;
}

console.log(recursiveKeys('', obj))

edited Apr 28, 2022 at 15:13

answered Apr 28, 2022 at 14:55

danh

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2 Comments

Nilton Schumacher F Over a year ago

For multiple objects inside objects, this didn't work.

danh Over a year ago

@NiltonSchumacherF - edited to add data with multiple top-level objects and deeply nested objects. Works to the extent I understand the objective of the question.

julianobrasil · Accepted Answer · 2022-04-28 15:25:39Z

0

function getKeys(obj) {
  return Object.keys((typeof obj === 'object' && obj) || {}).reduce((acc, key) => {
    if (obj[key] && typeof obj[key] === 'object') {
      const keys = getKeys(obj[key]);
      keys.forEach((k) => acc.add(`${key}.${k}`));
    } else {
      acc.add(key);
    }
    return acc;
  }, new Set());
}

// accumulate the keys in a set (the items of the array may
// have different shapes). All of the possible keys will be
// stored in a set
const s = itemsArray.reduce(
  (acc, item) => new Set([...acc, ...getKeys(item)]),
  new Set()
);

console.log('Keys => ', Array.from(s));

edited Apr 28, 2022 at 15:25

answered Apr 28, 2022 at 15:11

julianobrasil

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2 Comments

Nilton Schumacher F Over a year ago

Could you do a fix please, in case the key is there but the value is null, I still want to get the key, although I got and null error

julianobrasil Over a year ago

I believe it works for null values too. Do you have an example of a case where it fails?

PeterKA · Accepted Answer · 2022-04-28 15:32:54Z

0

You can use recursion as follows. Since typeof([1,3,5]) is object, we also have to confirm that value is not an array, !Array.isArray(value):

const obj = { id: 10, obj: {name: "Name1", obj2: {name2: "Name2", test: "Test"}}};

const getKeys = (o,p) => Object.entries(o).flatMap(([key,value]) => 
    typeof(value) === 'object' && !Array.isArray(value) ? 
        getKeys(value, (p?`${p}.`:"") + key) : 
        (p ? `${p}.`: "") + key
);

console.log( getKeys(obj) );

answered Apr 28, 2022 at 15:32

PeterKA

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