Save multiple data with a loop in FirebaseDatabase - Swift IOS

Question

with my code I would save multiple data with a loop in my Firebase Database. I have used a while loop to save some strings in my Database but my app saves only the last book and I don't know how to fix this problem. Any ideas?

let refUsers = FIRDatabase.database().reference().child("Users").child("User" + tag_login).child(user_key).child("Books").child("Others")
        let key = refUsers.childByAutoId().key
        let multipleBooksValues = ["multipleBooks": "Yes", "read": "Yes"] as NSDictionary
        refUsers.child(key).setValue(multipleBooksValues)

        let refBooks = FIRDatabase.database().reference().child("Books").child("User's books").child(book_key)

        var bookNumber = 0

        let numberOfBooks = bookList.count

        while bookNumber < numberOfBooks {

            let book = bookList[bookNumber]

            let values = ["book_key\(bookNumber)" : book.book_key!] as NSDictionary
            refUsers.child(key).child("multipleBooksNumber").setValue(values)
            refBooks.updateChildValues(["onGoingNegotiations" : "Yes", "other_user_key" : self.user_key, "other_tag_login": self.tag_login])

            refUsers.child(key).child("multipleBooksNumber").observe(.value, with: { (snapshot) in
                let numberChildren = Int(snapshot.childrenCount - 1)
                if numberChildren == bookNumber{
                    bookNumber += 1
                }
            })

        }

Thank you in advance.

Frank van Puffelen · Accepted Answer · 2016-10-29 14:55:33Z

1

Each next book in your loop is overwriting the previous book. The easiest way to prevent this is to call setValue() one level deeper in the tree:

    while bookNumber < numberOfBooks {

        let book = bookList[bookNumber]

        refUsers.child(key).child("multipleBooksNumber/\(bookNumber)").setValue(book.book_key!)

    }

Note though that the Firebase documentation and blog recommend against using arrays like this for storing data. Either store the books under their natural key:

refUsers.child(key).child("multipleBooksNumber/\(book.book_key!)").setValue(true)

Or store them under so-called push IDs:

refUsers.child(key).child("multipleBooksNumber").childByAutoId().setValue(book.book_key!);

answered Oct 29, 2016 at 14:55

Frank van Puffelen

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1 Comment

Carlo Over a year ago

Thanks very much :)

valivaxa · Accepted Answer · 2016-10-29 13:25:51Z

0

Maybe the problem is that you save all books to the same path and they are being re-written one by another all the time, so only the last one is being saved in the end? You specify your key once

 let key = refUsers.childByAutoId().key

and then save all values to path

refUsers.child(key).child("multipleBooksNumber").setValue(values)

edited Oct 29, 2016 at 13:25

answered Oct 29, 2016 at 13:18

valivaxa

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1 Comment

Carlo Over a year ago

I want to save these results inside a single key. I think that the problem is in the loop.

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