Btukfyl

I've got a problem with queryOrdered() function, I don't know really how to deal with...

Assuming my database structure is :

Planes{

Uid{

    SE{

        AutoID{

            .Auto-Id

            .Picture

            .Registration

            .Type

            .model

        }

        AutoID{

            //Same as first one

        }

    }

    ME{

        AutoID{

            //Same as first one

        }

    }

}}

In this part of my Database I would like to run a search by .Registration

So I've been set my reference to Planes > UId

And after do this code :

var acftPickerSelected = aircrafts[listAcftsPicker.selectedRow(inComponent: 0)]



    if let user = Auth.auth().currentUser{

        // user is connect

        let ref = Database.database().reference()

        let userID = Auth.auth().currentUser?.uid



        let ev = ref.child("Planes").child(userID!)



        ev.queryOrdered(byChild: "Registration").queryEqual(toValue: acftPickerSelected).observeSingleEvent(of: .value) { (snapshot: DataSnapshot) in

            for child in snapshot.children {

                let value = snapshot.value as? NSDictionary



                self.pickerRegi = value?["Registration"] as? String ?? "..unknown.."

                self.stdbPickerType = value?["Type"] as? String ?? "..unknown.."

                self.pickerModel = value?["model"] as? String ?? "..unknown.."



                print("Avion : (self.pickerRegi) - (self.pickerModel) - (self.stdbPickerType)")

            }

        }

But this message appears :

2018-11-27 18:03:54.797824+0100 XXXXXXXXXX[12954:527986] 5.10.0 - [Firebase/Database][I-RDB034028] Using an unspecified index. Your data will be downloaded and filtered on the client. Consider adding ".indexOn": "Registration" at /Planes/BJMhmQzJXldULc5X9Y2WzjFEs9a2 to your security rules for better performance

So I've been add the rules on firebase like this :

{"rules": {

"Planes":{

  "$uid":{

  ".indexOn": ["Registration"],

    ".write": "$uid === auth.uid",

    ".read": "$uid === auth.uid"

  }

},

".read": true,

".write": true}}

And now the error message didn't appear anymore but nothing happen in this part :

self.pickerRegi = value?["Registration"] as? String ?? "..unknown.."

            self.stdbPickerType = value?["Type"] as? String ?? "..unknown.."

            self.pickerModel = value?["model"] as? String ?? "..unknown.."



            print("Avion : (self.pickerRegi) - (self.pickerModel) - (self.stdbPickerType)")

How can I fix it?

Thanks for your help.

There are two things going on here;

1. indexOn


2. The observer

and in this case, the indexOn is not the issue.

The indexOn is most important in a production app and it's basically a performance increase for queries. For testing, eliminate that variable first as it's not the cause of the issue. Reset the rules to default temporarily

{

  "rules": {

    ".read": "auth != null",

    ".write": "auth != null"

  }

}

The real issue is the observe as it's not deep enough to reach the data you're trying to get to. You're missing the 'SE' level. Here's a re-write

let uidRef = ref.child("Planes").child(userID)

let seRef = uidRef.child("SE") //this is the child node to query

seRef.queryOrdered(byChild: "Registration").queryEqual(toValue: acftPickerSelected)

  .observeSingleEvent(of: .value) { snapshot in

      for child in snapshot.children {

          let childSnap = child as! DataSnapshot

          let dict = childSnap.value as! [String: Any]

          let reg = dict["Registration"] as? String ?? "No Reg"

          let mod = dict["model"] as? String ?? "No Model"

          print(reg, mod)

      }

}

the way it's written in your question, the query will query the next level up: it's expecting to find a Registration node directly under the SE and ME nodes. But those nodes only contain the autoId nodes.

EDIT:

Changing the structure by flattening (denormalizing) it would also be another option

Planes

   Uid

      AutoID

         .Auto-Id //note, if the is the same as the key, its not needed

         .Picture

         .Registration

         .Type

         .model

         .se_or_me: "SE"

      AutoID

         .Auto-Id

         .Picture

         .Registration

         .Type

         .model

         .se_or_me: "ME"