Cloud Firestore: Update fields in nested objects with dynamic key

Question

following the official documentation of firestore :

{
    name: "Frank",
    favorites: { food: "Pizza", color: "Blue", subject: "recess" },
    age: 12
}

// To update favorite color:
db.collection("users").doc("frank").update({
    "favorites.color": "Red"
})

I would like to use a dynamic key instead of color.

db.collection("users").doc("frank").update({
    "favorites[" + KEY + "].color": true
});

this is of course not possible and will throw an error.

I've been trying to do this :

db.collection("users").doc("frank").update({
    favorites: {
        [key]: {
            color": true
        }
    }
});

It is actually updating with the right key but unfortunately, it is overwriting the other keys (they are being deleted).

score 112 · Accepted Answer · answered Nov 14 '17 at 22:16

112

I found the solution inspired by a firebase solution (replacing "/" by ".").

var usersUpdate = {};
usersUpdate[`favorites.${key}.color`] = true;

db.collection("users").doc("frank").update(usersUpdate);

answered Nov 14 '17 at 22:16

Brieuc

3,994
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9

Related doc -> https://firebase.google.com/docs/firestore/manage-data/add-data?authuser=0#update_fields_in_nested_objects – Kushagra Gour Jan 05 '18 at 06:04
2

I'm wondering if that actually works. I would expect it to overwrite the current value of `usersUpdate` with the new one with a single value, namely `{favorites {KEY: {color: true}}}`.If what you say is correct, then there would be no way to actually update `usersUpdate` to a completely new value. – Apr 23 '18 at 03:31
4

more briefly, @Georg Hackenberg points out this solution: `db.collection('users').doc('frank').update({ [\`favorites.${key}.color\`] = true })` – Nth.gol Jun 17 '18 at 14:30
1

Why is it invalid? You can use backticks in es6. This solution still work, it is really similar to the answer below. https://developers.google.com/web/updates/2015/01/ES6-Template-Strings – Brieuc Sep 08 '18 at 09:27
3

This solution is wrong as this will create a new field usersUpdate of type map with child favorites.${key}.color : true - if key=1234 then usersUpdate field will look like ```usersUpdate { favorites.1234.color : true } ``` – sachin rathod Jan 29 '20 at 18:54
I don't understand why you're saying it's wrong. The is the intended purpose is to have a key such as "favorites.1234.color", at least it was the way to do it at that time to achieve something similar than Firebase. – Brieuc Jan 30 '20 at 08:19
1

For me it worked. What is weird is that it highlight the entire map even I'm updating only one field of only one value of map – Leonardo Rick Sep 04 '20 at 21:19

Georg Hackenberg · Answer 2 · 2021-09-29T09:26:19.590

73

This solution worked for me:

db.collection('users').doc('frank').update({
  [`favorites.${key}.color`]: true
});

edited Sep 29 '21 at 09:26

answered May 07 '18 at 19:54

Georg Hackenberg

759
5
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3

Correct solution. – Fernando Rojo Aug 25 '19 at 17:37
1

db.collection('users').doc('frank').update({ [` favorites.${key}.color `]: true }) – coolcool1994 Dec 31 '19 at 09:16
3

This solution is correct. Also alternate solution : ```db.collection('users').doc('frank').update({ [`favorites.${key}.color `]: true })``` and also be careful enough to avoid blank spaces inside [``] section i.e you would end up doing wrong if you include blank space ```db.collection('users').doc('frank').update({ [` favorites.${key}.color `]: true }``` – sachin rathod Jan 29 '20 at 18:46
doesn't make any nested stuff though :/ just update – Zack Heisenberg Jun 09 '20 at 11:18
10

Note for lurkers: This works for update, but for set it saves as a single prop with dot in it's name, not as a nested property. – Sebastijan Dumančić Sep 14 '20 at 12:58

score 32 · Answer 3 · answered Mar 27 '20 at 02:36

32

Just a note about a potential pitfall: After discovering that you can update nested fields using a dot syntax, I tried using set() the same way, since I needed it to work whether the object already exists or not:

var updateObj = {['some.nested.property']: 9000};
docRef.set(updateOb, {merge: true});

Unfortunately, this doesn't work – it sets a property whose key is some.nested.property instead. Inconsistent, but okay.

Fortunately, it appears that set(updateObj, {merge: true}) does a deep merge, so if you construct your update object as a fully nested object, your nested objects will also be properly merged:

// create the object
db.doc('testCollection/doc').set({p1: {['p2']: {p3: true}}}, {merge: true})
// update the existing object
db.doc('testCollection/doc').set({p1: {['p2']: {p4: true}}}, {merge: true})

// result is now this:
{ p1: { p2: { p4: true, p3: true } } }

answered Mar 27 '20 at 02:36

undefined

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Wat. When did they ninja in that? I'm sure it wasn't always like that. It used to do a shallow merge IIRC. But hey, it extremely useful, so thanks for writing about it! – DarkNeuron Aug 12 '21 at 15:26
You made my day man, I was having the same issue for a long time – tinyCoder Oct 10 '21 at 10:58
Wow. I had no clue this worked. Very nice. Wish it was documented somewhere. – Allen Feb 14 '22 at 14:39
Thanks, undefined, I was struggling with this one. – Shankaja Aroshana Mar 25 '23 at 19:34

score 3 · Answer 4 · answered Sep 10 '18 at 00:57

3

You can update specific fields of variable(ly) named nested objects like below.

ref.set({
    name: "Frank",
    favorites: { food: "Pizza", quantity: 2 }
});

//now the relevant update code
var name = "favorites";
var qty = 111;
var update = {};
update[name+".quantity"] = qty;
ref.update(update);

https://jsbin.com/hihifedizu/edit?js,console

answered Sep 10 '18 at 00:57

Ronnie Royston

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This is the most useful answer for general use. Thanks for helping me out. – khalidsafir Mar 24 '21 at 10:40

score 0 · Answer 5 · edited Sep 17 '21 at 05:48

0

I felt this is the simplest solutions of all the above :)

db.collection("users").doc("frank").update({
    [`favorites.${KEY}.color`]: true
});

edited Sep 17 '21 at 05:48

bad_coder

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answered Sep 17 '21 at 03:47

deepak n

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2
4

score 0 · Answer 6 · answered Mar 22 '22 at 03:19

0

you can use

var auxKey = "history." + someVar;
var dataToUpdate = {
   [auxKey]: "new data generated"
};
db.collection("users").doc("frank").update(dataToUpdate);

answered Mar 22 '22 at 03:19

Fenkan

1
1

result: {"history": {"valueOfSomeVar": "new data generated"}} – Fenkan Mar 22 '22 at 03:21

score 0 · Answer 7 · answered Aug 28 '22 at 14:50

0

2022 Update with Webversion 9 (modular):

const docRef = doc(db, 'users', frank); 

var usersUpdate = {};
usersUpdate[`favorites.${key}.color`] = true;

updateDoc(docRef, userUpdate);

answered Aug 28 '22 at 14:50

Stefan

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1
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Cloud Firestore: Update fields in nested objects with dynamic key

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