Transforming Observable’s output from Object to Array

Question

I have a Cloud Firestore document that is supposed to be an array of objects. It looks like this

docname: {
  0: {...}
  1: {...}
  2: {...}

This is expected, because I populated that document like this

myDocRef.set( {...user.myArray});

The problem I have is when I go to retrieve the data from the document. I currently do it like this

getUserItems(uid) {
  return this._db.doc<MyObj>(`users/${uid}/mysubcollection/items`).valueChanges(); 
}

That returns an object of objects and I need it to be an array of objects so that I can use forEach() on it.

I tried using the map() operator but its giving me some results I am not understanding.

So, my goal is to convert that object of objects to an array of objects and I tried this

items$.pipe(
      tap(item => console.log('before map', item )),
      map(item => [item]),
      tap(item => console.log('after map', item ))
    )
    .subscribe(...);

This does kind of work since it converts the object of objects to an array of objects but of course it puts all objects into the first dim of a two dim array to it looks like this

Array [Object(9)]

What can I do here to convert an object of objects to an array of objects so that my end result is like this

Array(9) [ {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…} ]

So going from this

Object(9) [ {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…} ]

to this

Array(9) [ {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…}, {…} ]

Why don't you create an empty array first and push each item in the array inside the "pipe" method? — Shuvo
– Shuvo, Commented Apr 13, 2019 at 4:22

Jack Bashford · Accepted Answer · 2019-04-13 04:20:11Z

1

If the order of the items in the array does not matter, you can just use Object.values:

const objectOfObjects = {
  0: { name: "Zero" },
  1: { name: "One" },
  2: { name: "Two" },
  3: { name: "Three" }
};
const unorderedArray = Object.values(objectOfObjects);
console.log(unorderedArray);

If they do matter, get both the key and the value first using Object.entries, then sort them in ascending order, and map out the values:

const objectOfObjects = {
  0: { name: "Zero" },
  1: { name: "One" },
  2: { name: "Two" },
  3: { name: "Three" }
};
const orderedArray = Object.entries(objectOfObjects).sort(([a], [b]) => a - b).map(([, obj ]) => obj);
console.log(orderedArray);

answered Apr 13, 2019 at 4:20

Jack Bashford

44.3k11 gold badges56 silver badges84 bronze badges

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

Collectives™ on Stack Overflow

Transforming Observable’s output from Object to Array

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related