How to perform compound queries with logical OR in Cloud Firestore?

Question

From the docs:

You can also chain multiple where() methods to create more specific queries (logical AND).

How can I perform an <

Answer 1

We have the same problem just now, luckily the only possible values for ours are A,B,C,D (4) so we have to query for things like A||B, A||C, A||B||C, D, etc

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As of like a few months ago firebase supports a new query array-contains so what we do is make an array and we pre-process the OR values to the array

if (a) {
array addObject:@"a"
}
if (b) {
array addObject:@"b"
}
if (a||b) {
array addObject:@"a||b"
}
etc

And we do this for all 4! values or however many combos there are.

THEN we can simply check the query [document arrayContains:@"a||c"] or whatever type of condition we need.

So if something only qualified for conditional A of our 4 conditionals (A,B,C,D) then its array would contain the following literal strings: @["A", "A||B", "A||C", "A||D", "A||B||C", "A||B||D", "A||C||D", "A||B||C||D"]

Then for any of those OR combinations we can just search array-contains on whatever we may want (e.g. "A||C")

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Note: This is only a reasonable approach if you have a few number of possible values to compare OR with.

More info on Array-contains here, since it's newish to firebase docs