CODEWITHSUNDEEP
swiftfirebasetableviewfirebase-realtime-database
askaale
askaale

Reputation: 1199

Firebase query ordering not working properly

Basically I have played with Firebase for the past week, and I recently stumbled upon the 'queryOrderedByChild()' that as far as I know - allows you to sort data in firebase. However, I seem to not get the proper results. My Firebase data looks like this: 

{
  "names" : {
    "-KHVUwXdVPHmrO_O5kil" : {
      "id" : "0",
      "name" : "Jeff"
    },
    "-KHVV7lCeac0cZNMi9fq" : {
      "id" : "3",
      "name" : "Stig"
    },
    "-KHVVCjXgl0XxasVOHF1" : {
      "id" : "13",
      "name" : "Ali"
    },
    "-KHVVJtyUO-yJZiompJO" : {
      "id" : "7",
      "name" : "Hannah"
    },
    "-KHVVR8tMSO1Oh7R8tR1" : {
      "id" : "2",
      "name" : "Amanda"
    }
  }
}

, and my code looks like this: 

ref.childByAppendingPath("names")
   .queryOrderedByChild("id")
   .observeEventType(.ChildAdded) { (snapshot:FDataSnapshot!) in
       if let myID = snapshot.value["id"] as? String {
           print(myID)
       }

The output is still in a random order, displaying: 0, 2,7,1,8,4 - Isn't this supposed to be numeric? What am I doing wrong? How can I sort it so it get's numeric either ascending or descending?

Upvotes: 2

Views: 1700

Answers (2)

Frank van Puffelen
Frank van Puffelen

Reputation: 598668

You say that you're ordering by a number, but the value of your id property is stored as a string.

Since you're storing them as a string, they will be returned in lexicographical order.

If you want them to be in numerical order, you should store them as numbers

"-KHVUwXdVPHmrO_O5kil" : {
  "id" : 0,
  "name" : "Jeff"
},

Alternatively, you could store the ids as zero-padded strings:

{
  "names" : {
    "-KHVUwXdVPHmrO_O5kil" : {
      "id" : "0000",
      "name" : "Jeff"
    },
    "-KHVV7lCeac0cZNMi9fq" : {
      "id" : "0003",
      "name" : "Stig"
    },
    "-KHVVCjXgl0XxasVOHF1" : {
      "id" : "0013",
      "name" : "Ali"
    },
    "-KHVVJtyUO-yJZiompJO" : {
      "id" : "0007",
      "name" : "Hannah"
    },
    "-KHVVR8tMSO1Oh7R8tR1" : {
      "id" : "0002",
      "name" : "Amanda"
    }
  }
}

Since the strings are all the same length, they will be sorted in the correct order. But you'll have to decide on the length of the string/maximum id value in the latter solution, so it seems worse.

Upvotes: 2

Igoretto
Igoretto

Reputation: 117

If you using order by child you going to order your id you no going to touch it's value.

Then maybe you have to try something like

  • (FIRDatabaseQuery *) queryOrderedByValue
    queryOrderedByValue: is used to generate a reference to a view of the data that's been sorted by child value.

Upvotes: 0

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