Firebase No properties to serialize found on class

Question

I'm bloqued creating a Firebase Database.

I'm trying to model a class. A very simple class:

package com.glups.model;

import com.google.firebase.database.IgnoreExtraProperties;

@IgnoreExtraProperties
public class AlumnoFB {

    private String nombre;
    private String apellidos;
    private String telefono;
    private String email;
    private Boolean tieneWhatsapp;
    private Boolean tieneTelegram;
    private Boolean tieneHangouts;
    private Long formaPago;
    private Double ratioHora;
    private Double precioHora;
    private Double horasCompensadas;

    public AlumnoFB() {
        // Default constructor required for calls to DataSnapshot.getValue(User.class)
    }

    public AlumnoFB(String nombre,
                    String apellidos,
                    String telefono,
                    String email,
                    Boolean tieneWhatsapp,
                    Boolean tieneTelegram,
                    Boolean tieneHangouts,
                    Long formaPago,
                    Double ratioHora,
                    Double precioHora,
                    Double horasCompensadas) {
        this.nombre = nombre;
        this.apellidos = apellidos;
        this.telefono = telefono;
        this.email = email;
        this.tieneWhatsapp = tieneWhatsapp;
        this.tieneTelegram = tieneTelegram;
        this.tieneHangouts = tieneHangouts;
        this.formaPago = formaPago;
        this.ratioHora = ratioHora;
        this.precioHora = precioHora;
        this.horasCompensadas = horasCompensadas;
    }
}

that is almost like a sample class from Firebase.

Application user obtained from getUser() has been logged on Firebase.

When I call SetValue:

AlumnoFB alumno = new AlumnoFB("", "", "", "", false, false, false, ((Integer)FormaPago.INT_NO_PAGADO).longValue(), 0.0, 0.0, 0.0);
    mDatabase.child("AlumnoFB").child(ControlClasesFirebase.getUser().getUid()).setValue(alumno) ;

A fatal exception raises.

06-10 10:17:37.179 13841-13841/com.glups.controlclases E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.glups.controlclases, PID: 13841 com.google.firebase.database.DatabaseException: No properties to serialize found on class com.glups.model.AlumnoFB
at com.google.android.gms.internal.zzaix$zza.<init>(Unknown Source)
at com.google.android.gms.internal.zzaix.zzj(Unknown Source)
at com.google.android.gms.internal.zzaix.zzaw(Unknown Source)
at com.google.android.gms.internal.zzaix.zzav(Unknown Source)
at com.google.firebase.database.DatabaseReference.zza(Unknown Source)
at com.google.firebase.database.DatabaseReference.setValue(Unknown Source)
at com.glups.controlclases.MainActivity$4.onClick(MainActivity.java:305)
at android.view.View.performClick(View.java:4780)
at android.view.View$PerformClick.run(View.java:19866)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5258)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)

I've checked types, and all are accepted. What's wrong?

Answer 1

Firebase require your Pojo to have public variables or getter/setter.

Change variable declarations to public

public String nombre;
public String apellidos;
public String telefono;
public String email;
public Boolean tieneWhatsapp;
public Boolean tieneTelegram;
public Boolean tieneHangouts;
public Long formaPago;
public Double ratioHora;
public Double precioHora;
public Double horasCompensadas;

Answer 2

If you are using proguard, some methods in the model could be stripped out depending on your configuration. As we know that there is no much optimization to POJO as it has only fields with getters and/or (optionally) setters, you can use the annotation "@Keep" so proguard will not delete any methods from this class.

Check this for more info: https://developer.android.com/studio/build/shrink-code.html

@Keep
public class Store {}

Answer 3

In my case I forgot to add a proguard rule to keep the model classes:

-keep class com.google.firebase.example.fireeats.model.** { *; }

This is same as @aselims's answer, just proguard version.

I found it in the official firestore example:

https://github.com/firebase/quickstart-android/blob/master/firestore/app/proguard-rules.pro

Answer 4

I have got this issue today and just resolve this providing getter/setter for private variables.

ex:

private String pid;

public String getPid() {
    return pid;
}

public void setPid(String pid) {
    this.pid = pid;
}

Now it's work perfectly without any error. Hope it will help newbies devs.