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).
I found the solution inspired by a firebase solution (replacing "/" by ".").
var usersUpdate = {};
usersUpdate[`favorites.${key}.color`] = true;
db.collection("users").doc("frank").update(usersUpdate);
This solution worked for me:
db.collection('users').doc('frank').update({
[`favorites.${key}.color`]: true
});
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 } } }