CODEWITHSUNDEEP
androidfirebasefirebase-realtime-database
E_K
E_K

Reputation: 2249

DatabaseException when iterating nested Firebase database nodes

I am trying to iterate a nested Firebase database that has the following datasnapshot:

 DataSnapshot { key = Presidents, value = {1={aspirantName=Uh Ky, thumbnail=434, currentVotes=324595}, position=1, 2={aspirantName=Rao O, thumbnail=3, currentVotes=32}, numberofAspirants=3, docketName=Presidents} }

But get this exception:

com.google.firebase.database.DatabaseException: Can't convert object of type java.lang.String to type com.example.esir.jualeader.Aspirant

the datasnapshot is a Log from 

private void getAspirantsData(DataSnapshot dataSnapshot) {
    aspirantsArrayList.clear(){
    Log.e("Ds", "" + dataSnapshot); //Prints  DataSnapshot { key = Presidents, value = {1={aspirantName=Uh Ky, thumbnail=434, currentVotes=324595}, position=1, 2={aspirantName=Rao O, thumbnail=3, currentVotes=32}, numberofAspirants=3, docketName=Presidents} }
    Iterable<DataSnapshot>iterable=dataSnapshot.getChildren();
    Iterator<DataSnapshot>iterator=iterable.iterator();
    while (iterator.hasNext()){
Aspirant aspirant=iterator.next().getValue(Aspirant.class); // com.google.firebase.database.DatabaseException: Can't convert object of type java.lang.String to type com.example.esir.jualeader.Aspirant
        Log.e("Aspirant ", "" + aspirant.getAspirantName()+" "+aspirant.getCurrentVotes()+" "+aspirant.getThumbnail());//This Works therefore Aspirant Object has Been Created
        aspirantsArrayList.add(aspirant);
    }
}

Can anyone assist on why the exception is occurring? And which string is it trying too convert into my Aspirant object.

This is my Aspirants Class

public class Aspirant {
    private String aspirantName;
    private int currentVotes;
    private int thumbnail;

    public Aspirant(){

    }
    public Aspirant(String aspirantName, int currentVotes, int thumbnail){
        this.aspirantName=aspirantName;
        this.currentVotes=currentVotes;
        this.thumbnail=thumbnail;
    }

    public String getAspirantName() {
        return aspirantName;
    }

    public void setAspirantName(String aspirantName) {
        this.aspirantName = aspirantName;
    }

    public int getCurrentVotes() {
        return currentVotes;
    }

    public void setCurrentVotes(int currentVotes) {
        this.currentVotes = currentVotes;
    }

    public int getThumbnail() {
        return thumbnail;
    }

    public void setThumbnail(int thumbnail) {
        this.thumbnail = thumbnail;
    }
}

The following is my Firebase database structure

{
    "Presidents" : {
      "1" : {
        "aspirantName" : "Urhu atta",
        "currentVotes" : 324595,
        "thumbnail" : 434
      },
      "2" : {
        "aspirantName" : "Rla Oga",
        "currentVotes" : 32,
        "thumbnail" : 3
      },
      "docketName" : "Presidents",
      "numberofAspirants" : 3,
      "position" : 1
    },
    "Senetors" : {
      "docketName" : "Senetors",
      "numberofAspirants" : 5,
      "position" : 2
    }
}

Upvotes: 0

Views: 247

Answers (2)

Frank van Puffelen
Frank van Puffelen

Reputation: 599176

You have incompatible data in your JSON. Under President you have two valid Aspirant objects:

  "1" : {
    "aspirantName" : "Urhu atta",
    "currentVotes" : 324595,
    "thumbnail" : 434
  },

And

  "2" : {
    "aspirantName" : "Rla Oga",
    "currentVotes" : 32,
    "thumbnail" : 3
  },

But you also have these properties, none of which can be converted to a Aspirant:

  "docketName" : "Presidents",
  "numberofAspirants" : 3,
  "position" : 1

This is one of the many reasons the Firebase documentation recommends against nesting different types of data under a common root. A better structure for your data would be:

"Dockets": {
    "Presidents" : {
      "docketName" : "Presidents",
      "numberofAspirants" : 3,
      "position" : 1
    },
    "Senetors" : {
      "docketName" : "Senetors",
      "numberofAspirants" : 5,
      "position" : 2
    }
},
"Candidates": {
    "Presidents" : {
      "1" : {
        "aspirantName" : "Urhu atta",
        "currentVotes" : 324595,
        "thumbnail" : 434
      },
      "2" : {
        "aspirantName" : "Rla Oga",
        "currentVotes" : 32,
        "thumbnail" : 3
      }
    },
    "Senetors" : {
      ... nothing here yet
    }
}

Now you can safely read all Aspirant objects from under the Candidates key.

Upvotes: 1

Nirel
Nirel

Reputation: 1925

Try to replace your whole "getAspirantsData" function with this one:

private void getAspirantsData(DataSnapshot dataSnapshot) 
{
aspirantsArrayList.clear()
Log.e("Ds", "" + dataSnapshot);
for(DataSnapshot snap : datasnapshot.getChildren()
    aspirantsArrayList.add(snap.getValue(Aspirant.class);
}

Upvotes: 0

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