Firebase queryEqualToValue with childKey

Question

I am trying to query data in my Firebase database using:

queryEqual(toValue: Any?, childKey: String?)

My database structure:

Schools {
    testUID1 {
        schoolNameLC: test school 1
    }
}

My query is:

databaseReference.child("Schools").queryEqual(toValue: "test school 1", childKey: "schoolNameLC").observe(.value) { (snap) in
        print(snap)
    }

This query prints out null and I can't quite get it to work. Because of the way my app is set up, I don't know that the key schoolNameLC has a value testSchool1 under the parent key of testUID1. All I want to do is search through the Schools in my database and return anything with a schoolNameLC value of test school 1.

Answer 1

The two-parameter queryEqualToValue:childKey: (and its brethren queryStartingAtValue:childKey: and queryEndingAtValue:childKey:) are unfortunately some of the most misunderstood methods in the Firebase Database API.

To order by a child and then filter on a value of that child, you have to call queryOrderedByChild().queryEqualToValue(). So as @ElCaptainV2.0 said:

databaseReference.child("Schools")
    .queryOrderedByChild("scho‌​olNameLC")
    .queryEqua‌​lToValue("test school 1")

You only should use the childKey: parameter if you also want to start at a specific key in all nodes that have the same matching test school 1 value. This overload is really mostly useful when you're trying to paginate/endless scroll results.