DatabaseReference is missing a constructor with no arguments

[Evans Attafuah]

I keep getting this error and I haven't found any relevant solution on the internet. Am using a custom model with firebase annotation. when I make updates to a field on firebase I fire a value change event and this error shows up. Has anybody encountered this same issue. Help Needed.

Best Regards,

Evans. 

[Evans Attafuah]

here is my code

@IgnoreExtraProperties
public class Profile {

    private String displayName;
    private String statusMessage;
    private DatabaseReference contacts;
    private String thumbUrl;
    private String imageUrl;
    private String userId;
    private String pushId;
    private String theme;

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

    public String getUserId() {
        return userId;
    }

    public void setUserId(String userId) {
        this.userId = userId;
    }

    public String getDisplayName() {
        return displayName;
    }

    public void setDisplayName(String profileName) {
        this.displayName = profileName;
    }

    public String getStatusMessage() {
        return statusMessage;
    }

    public void setStatusMessage(String statusMessage) {
        this.statusMessage = statusMessage;
    }

    public DatabaseReference getContacts() {
        return contacts;
    }

    public void setContacts(DatabaseReference contacts) {
        this.contacts = contacts;
    }

    public String getThumbUrl() {
        return thumbUrl;
    }

    public void setThumbUrl(String thumbURL) {
        this.thumbUrl = thumbURL;
    }

    public String getImageUrl() {
        return imageUrl;
    }

    public void setImageUrl(String imageUrl) {
        this.imageUrl = imageUrl;
    }

    public String getPushId() {
        return pushId;
    }

    public void setPushId(String pushId) {
        this.pushId = pushId;
    }

    public String getTheme() {
        return theme;
    }

    public void setTheme(String theme) {
        this.theme = theme;
    }

    @Exclude
    public HashMap<String, Object> toMap() {
        HashMap<String, Object> result = new HashMap<>();

        if (displayName != null) {
            result.put(Config.KEY_DISPLAY_NAME, displayName);
        }

        if (statusMessage != null) {
            result.put(Config.KEY_STATUS_MESSAGE, statusMessage);
        }

        if (thumbUrl != null) {
            result.put(Config.KEY_THUMB_URL, thumbUrl);
        }

        if (imageUrl != null) {
            result.put(Config.KEY_IMAGE_URL, imageUrl);
        }

        if (pushId != null) {
            result.put(Config.KEY_PUSH_ID, pushId);
        }

        if (theme != null) {
            result.put(Config.KEY_THEME, theme);
        }

        return result;
    }

}

public static void getProfile(final String userId, final ProfileListener.onLoad onLoad) {

    //create a profile reference
    //use the single event listener to retrieve data
    final DatabaseReference profileReference = FirebaseDatabase.getInstance().getReference().child(Config.REF_PROFILES).child(userId);
    profileReference.addListenerForSingleValueEvent(new ValueEventListener() {

        @Override
        public void onDataChange(DataSnapshot profileSnapshot) {
          //  new Testable.Spec(userId).describe("change event").expect(profileSnapshot.getValue()).run();
            if (profileSnapshot.exists()) {
                    Profile profile = profileSnapshot.getValue(Profile.class);
                    profile.setUserId(profileSnapshot.getKey());
                    // profile.setDisplayName(userContact.getDisplayName());
                    onLoad.load(profile);


            }
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });
}

[Michael Lehenbauer]

Hi Evans,

The problem is DatabaseReference can't be read/written to Firebase Database because it doesn't have a default no-argument constructor (see requirements for Java objects written to Firebase Database here).  So you'll either need to remove getContacts() from Profile, make it private, or add the @Exclude annotation to prevent it from being serialized.

Hope this helps,

-Michael

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[GmailMe]

getContacts is not part of the profile model. Thanks for this. 

Sent from my iPhone 6

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