Android Firebase Realtime: Writing an object with nested objects into db

Question

Is it possible to write a nested structure into firebase realtime db?

In my case I want to write a user to DB which have a reference to a Socks object which have String properties. In the db I need a child called "SocksCards" with childs with its properties. With this sample code the socksCard object is ignored, the user data is updated.

public void onDataChange(@NonNull DataSnapshot snapshot) {
                    User user = snapshot.getValue(User.class);                    
                    user.addSocksCards(socks);
                    userDb.setValue(user);
                }

public class User {
    public String username, surname, firstName, email, id, gender;
    private SocksCard socksCards;
    public User(){
    }

    public User(String username, String surname, String firstName, String email, String id, String gender){
        this.username = username;
        this.surname = surname;
        this.firstName = firstName;
        this.email = email;
        this.id = id;
        this.gender = gender;
    }

    public void addSocksCards(SocksCard sc){
        this.socksCards = sc;
    }
}

public class SocksCard {
    private String socksID;

    public SocksCard(String socksID){
        this.socksID = socksID;
    }

    public String getSocksID() {
        return socksID;
    }

}

Frank van Puffelen · Accepted Answer · 2021-06-04 15:57:56Z

1

Firebase only consider public fields, getters and setters when reading/writing Java objects from/to the database. Since SocksCard socksCards is private, and there is no getters and/or setter, the field is indeed ignored.

The two simplest approaches are to either mark the field as public:

public SocksCard socksCards

, or to add a public getter for it:

public SocksCard getSocksCards(){
    return this.socksCards;
}

answered Jun 4, 2021 at 15:57

Frank van Puffelen

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2 Comments

Symbiose Studios Over a year ago

Oh my... what stupid mistake. Thank you! Works perfectly. Btw. is this the way to go to update/append data? I Have not found a better way.

Frank van Puffelen Over a year ago

I tend to prefer performing the writes on the deepest level, so would probably do something like FirebaseDatabase.getInstance().ref("users").child(uid).child("socksCards").setValue(socks). But that's a personal preference, nothing that makes it pertinently better that I know of.

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