How to remove multiple elements from a Firestore Array dynamically? - node.js

Question

I want to remove multiple elements from my Firestore array:
var eliminatedThisRound = []
for (const player in players){
if (players[player].eliminated === false && players[player].answer !== answer) {
eliminatedThisRound.push(players[player].uid);
}
}
var update = {
roundFinished: true,
nextRound: date.valueOf() + 12000,seconds
players: updatedPlayers,
remainingPlayers: admin.firestore.FieldValue.arrayRemove(eliminatedThisRound)
}
await t.update(gameRef, update);
The above returns this error:
transaction failure: Error: Element at index 0 is not a valid array element. Nested arrays are not supported.
So it would be fine if I knew the values, as I could do something like this:
remainingPlayers: admin.firestore.FieldValue.arrayRemove("player1", "player2")
However I haven't found a way to make the parameter of arrayRemove() dynamic.
Any idea?

Answer 1

You need to use the Spread operator, as follows, in order to pass all elements of eliminatedThisRound as arguments to the arrayRemove() method.
var eliminatedThisRound = []
for (const player in players){
if (players[player].eliminated === false && players[player].answer !== answer) {
eliminatedThisRound.push(players[player].uid);
}
}
var update = {
// ...
admin.firestore.FieldValue.arrayRemove(...eliminatedThisRound)
}
await t.update(gameRef, update);
Note that you should have at least one element in the Array, otherwise you will call arrayRemove() with 0 argument while it requires at least 1 argument. So you may check the array length before assigning the remainingPlayers property to the update Object.

Answer 2

You can pass a single value or an array of values from variables like this to arrayRemove():
var removingPlayersId = ['player1', 'player2'];
admin
.firestore()
.doc('game/someID')
.set(
{
remainingPlayers: admin.firestore.FieldValue.arrayRemove(
removingPlayersId
),
},
{ merge: true }
);