Firebase -How to loop through snapshot.hasChild("...")

Question

My database is laid out like below

users
  |
  @--uidABC
       |
       |---phone:"+13125550690"
       |
       |---followers
              |
              |----uid123
              |      |---timeStamp:111222
              |
              |----uid456
              |      |---timeStamp:777999

I use .observeSingleEvent to check to see if uidABC exists and if it does I want to check to see if there is a child named followers under that path.

I can use snapshot.hasChild("followers") to see if it's available and if it is how can I loop through all the children underneath snapshot.hasChild("...")?

I use the code below but it's looping through the wrong snapshot. It using the top level one when it should use whatever DataSnapshot is under followers

let ref = Database...child("users").child(uidABC)
ref.observeSingleEvent(of: .value, with: { (snapshot) in

    if !snapshot.exists() {

        // this user doesn't exist
        return
    }

    if !snapshot.hasChild("followers") {

       // this user exists but has no followers
       return
    }

    // this user exists and has followers now loop through them
    for uid in snapshot.children {

        let snapshot = uid as! DataSnapshot

        if let dict = snapshot.value as? [String:Any] {
            let timeStamp = dict["timeStamp"] as? Double
            // eg. check for a specific timeStamp
         }
     }
})

excitedmicrobe · Answer 1 · 2019-09-23T16:19:12.067

0

Use child:

// this user exists and has followers now loop through them
for uid in snapshot.childSnapshot("followers") {

    guard let snapshot = uid as! DataSnapshot else {
     // Followers error
    }

    if let dict = snapshot.value as? [String:Any] {
        let timeStamp = dict["timeStamp"] as? Double
        // eg. check for a specific timeStamp
     }
 }

You can find more here: Iterate over snapshot children in Firebase

edited Sep 23 '19 at 16:19

answered Sep 04 '19 at 08:19

excitedmicrobe

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thanks I tried it but got an error -Value of type 'DataSnapshot' has no member 'child'; did you mean 'children'? – Lance Samaria Sep 04 '19 at 09:06
`child` was renamed to `childSnapshot(forPath: )` thanks for correcting me:) @LanceSamaria – excitedmicrobe Sep 05 '19 at 10:21
I didn’t even I know I was correcting you. I thought you were closing an entirely different snapshot child property. Thanks for the assistance – Lance Samaria Sep 05 '19 at 22:39

Lance Samaria · Accepted Answer · 2019-09-06T14:12:46.483

I got the answer from here and here

let ref = Database...child("users").child(uidABC)
ref.observeSingleEvent(of: .value, with: { (snapshot) in

    if !snapshot.exists() {

        // this user doesn't exist
        return
    }

    if !snapshot.hasChild("followers") {

        // this user exists but has no followers
        return
    }

    // this user exists and has followers now loop through them
    let childSnapshot = snapshot.childSnapshot(forPath: "followers") {

    for child in childSnapshot.children {

        let snap = child as! DataSnapshot

        let uid = snap.key

        if let dict = snap.value as? [String: Any] {

            let timeStamp = dict["timeStamp"] as? Double ?? 0
            // eg. check for a specific timeStamp
        }
    }
})

Firebase -How to loop through snapshot.hasChild("...")

2 Answers2