The Problem
What you need is something similar to array-contains-all.
So let's say that in firebase you have this:
And then in your code you have something like this:
const usersIDs = [
'q4nemfzg19OCmwm1EauiZwdYD4z1',
'UzmgPRtlRSZX44erF6VrkYQ5Kyf1',
];
Then you want to compare with something like this:
yourCollectionRef.where('users', 'array-contains-all', usersIDs).get()
// or
yourCollectionRef.where('users', '==', usersIDs).get()
But this is currently not possible. The array-contains-all is still a requested feature and the == is not gonna work because the type of the value has to be string, boolean, number, Time, null or docRef and can't be compared to an array.
The Solution
So the good news is that I have a solution for you in case you are willing to change your collection structure.
Instead of saving the data in array, save it in a map object and the items would be the keys.
Like this:
And then you can easily use the filter == as you want. Of course you can transform the array into a map object or simply have it like this:
const usersMap = {
q4nemfzg19OCmwm1EauiZwdYD4z1: null,
UzmgPRtlRSZX44erF6VrkYQ5Kyf1: null,
};
And this would be your final query:
yourCollectionRef.where('usersMap', '==', usersMap).get();
Then if you need in the future to get all of the documents from a specific user that's inside the usersMap you can use this query here:
yourCollectionRef.where(`usersMap.${userId}`, '==', null).get();
