Retrieve the key of a node base on child

Question

I'm trying to get the key of a node based on the child. Here's my structure

Code:

RESTAURANTS
    KTNfWKLD0isCsrpys
        name: “McDonalds”
        loc: “LA”
    KTNfWILD0iIkLLekc
        name: “KFC”
        loc: “LV”

Code:

FIRDatabase.database().reference().child("RESTAURANTS").queryOrderedByChild("name").queryEqualToValue("McDonalds").observeEventType(.Value, withBlock: { (snapshot) in
    print(snapshot.key)
}, withCancelBlock: nil)

How can I get the key of "McDonalds" in a query?

what;s the output of `print(snapshot.key)`? – Bista Oct 07 '16 at 07:44 — Bista, Oct 07 '16 at 07:44
It outputs "RESTAURANTS". – LEVIS OGCPAS Oct 07 '16 at 07:57 — LEVIS OGCPAS, Oct 07 '16 at 07:57

Bhavin Bhadani · Accepted Answer · 2016-10-07T07:52:06.597

3

You have to use allKeys to get keys from snapshots and than loop it to get key one by one. Try this code

FIRDatabase.database().reference().child("RESTAURANTS").queryOrderedByChild("name").queryEqualToValue("McDonalds").observeEventType(.Value, withBlock: { (snapshot) in
   if snapshot.exists() {
      for key in (snapshot.value?.allKeys)!{
          print(key)
      }
   } 
}

As @Frank van Puffelen said, This way of iterating loses the ordering of the child nodes. If you want to get ordered list than use snapshot.children first

edited Oct 07 '16 at 07:52

answered Oct 07 '16 at 07:45

Bhavin Bhadani

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Note that this way of iterating loses the ordering of the child nodes. While that likely doesn't matter in this specific case (since OP uses an equality check), I find it in general best to stick with iterating over `snapshot.children` first and only then getting the `.value` of each child. – Frank van Puffelen Oct 07 '16 at 07:49
@FrankvanPuffelen Hi! I've been reading many posts on ordering based on descending with Firebase and I do need to keep the order, but am having trouble getting the key or value from a child when I iterate over children. In iOS it says child (NSFastEnumerationIterator) has no member key or value. It returns under each child the data that I have as a dictionary, but I need the key for that child. Thanks in advance! I have found your other comments in other posts helpful as well. – Renee Olson May 17 '17 at 00:56
@FrankvanPuffelen This is just my test data right now to understand how it works. But using the observeSingleEvent with .value, which works best for what I need. Below is a print statement of the entire child when I iterate. I cannot seem to find any way to get the key called " today" for this child. I can get the snapshot.key, but that is not what I need. Do you have any thoughts? ` child is Snap (today) { status = answered; time = "-1494972374.35696"; }` – Renee Olson May 17 '17 at 01:23
@FrankvanPuffelen Sorry for all the comments, but while searching I found that you answered my question, but currently it appears to not work (child.key) in iOS. Here's a link to your answer in 2016 - http://stackoverflow.com/questions/41307826/searching-through-child-values-firebase-swift – Renee Olson May 17 '17 at 01:33
@FrankvanPuffelen I was able to get help from firebase support. Turns out now you have to do - for child in snapshot.children.allObjects as! [FIRDataSnapshot] { print(child.key) } – Renee Olson May 18 '17 at 04:14

Retrieve the key of a node base on child

1 Answers1