Query Firebase Database Swift - json

Question

I've been trying to create some queries for my database but without success. This is the first time when dealing with queries in Firebase and find them a bit confusing.
I use a real-time database
My database looks like this :
-> users
->profile
->uid1
->email : "some#email.com"
->name : "some_name"
->favourite
->id1
->title : "some_title"
->date : "some_date"
->id : "id1"
->id2
->title : "some_title"
->date : "some_date"
->id : "id2"
->uid2
->email : "some#email.com"
->name : "some_name"
->favourite
->id1
->title : "some_title"
->date : "some_date"
->id : "id1"
->id2
->title : "some_title"
->date : "some_date"
->id : "id2"
The queries I've been trying to make:
Check whether a specific uid is already in the database.
Check whether a specific id from favourite is already in the database at a known uid.
Any ideas how to perform these queries?

Answer 1

Depends if you are using the real-time database or Firestore. But because you want to do queries I suggest to use Firestore and you could implement it this way:
// Create a path where you want the query to search
let storageReference = Firestore.firestore().collection("users/profile")
let query = storageReference.whereField("uid", isEqualTo: givenUID )
query.getDocuments { (snapshot, error) in
if let snapshot = snapshot {
for document in snapshot.documents {
let data = document.data()
}
}
}
In real-time database you can't use queries but you can implement it like this and see if the document is available:
let databaseRef = Database.database().reference(withPath: "users/profile/givenUID")
databaseRef.observeSingleEvent(of: .value, with: { (snapshot) in
if snapshot.exists() {
// UID is in the database
} else {
// UID not found
}
})
Then do the same with a reference for favorites!