I'm unable to retrieve the data which is nested inside "Leagues" and "Season".
In the database below, I cannot retrieve Season 2016/2017 points and results.
I am able to access the data that is not nested, such as Email and Username without problems
"Users" :
"User1" : {
"Email" : "dfs#sdf.com",
"Last_login" : "5:15pm",
"Username" : "Test",
"Leagues" : {
"FootballLeague" : true,
"CricketLeague" : true
},
"Season" : {
"2017" : {
"Points" : 5,
"Results" : 2
"newdata" : {
"randomdata1: data1",
"randomdata2: data2"
},
}
"2018" : {
"Points" : 7,
"Results" : 2
}
}
The following class is what I'm using to store data as objects:
public class Users {
private String Username;
private String Email;
private String Last_login;
private Map<String, Boolean> Leagues;
private Map<String, thisSeason> Season;
public Users() {
}
//All getters and setters for the strings.
public Map<String, Boolean> get_joined_Leagues() {
return Leagues;
}
public void set_joined_Leagues(Map<String, Boolean> leagues) {
Leagues = leagues;
}
public Map<String, thisSeason> getSeason() {
return Season;
}
public void set_thisSeason(Map<String, thisSeason> season) {
Season = season;
}
public static class thisSeason {
private int Points;
private int Results;
private Map <String, thisNewData> newdata;
public thisSeason() {
}
public int getthisSeason_results() {
return Results;
}
public void setthisSeason_results(int resultsin) {
Results = resultsin;
}
public int getthisSeason_points() {
return Points;
}
public void setSeason_points(int Pointsin) {
Points = Pointsin;
}
public Map<String, thisNewData> getNewData() {
return newdata;
}
public void set_thisNewData(Map<String, thisNewData> newdata_in) {
newdata= newdata_in;
}
public static class thisNewData {
private String randomdata1;
private String randomdata2;
//Getters and Setters
}
Here is part of my Java class where I access the Database:
List<Users> usersList= new ArrayList<Users>();
DatabaseReference fbDB = FirebaseDatabase.getInstance().getReference();
fbDB.child("Users").addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
if (dataSnapshot.exists()) {
for (DataSnapshot ds : dataSnapshot.getChildren()) {
Users C = ds.getValue(Users.class);
usersList.add(C);
System.out.println(C.getSeason().getthisSeason_points()); //ERROR occurs here - null object reference
}
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
I get a null object reference error as shown in the code above.
Also, on a slight side note - I'm aware my implementation for getting Leagues is incorrect. How can I retrieve the keys instead?
The main problems that I found in your code:
First, your Leagues object:
Well, it should not be a custom object at all, if it stays in the current structure, but a Map. This is the map object - a collection which has a key, and a value, just like a child in the Realtime Database.
If a league name (=key) didn't have a true (=value) next to it - the names could have been stored in String variables, but this is not the case, because every child in the Realtime Database must have a value, and storing a "dummy" value next to a league name makes each league a part of a Map. This current "dummy" is a boolean, and that's why this will be the leagues' data type:Map<String, Boolean> leagues.
Second, your Season object:
You are confusing between one season and many seasons. Your child - "Season" actually stores a lot of seasons. Thats why this case will be similar to the one above - each season's time is the key and the season itself is the value.
Therefore, the User class's variables should be:
private String Username;
private String Email;
private String Last_login;
private Map<String,Boolean> Leagues;
private Map<String, Season> Seasons;
Related
I'm not getting the output from Firebase database. It's not returning anything. Here is my data structure.
I also tried getting value through query but it returned database error:
Cannot convert java.util.hashmap to String
FirebaseDatabase database = FirebaseDatabase.getInstance();
DatabaseReference myRef = database.getReference().child("Member").push();
myRef.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for (DataSnapshot ds : dataSnapshot.getChildren()) {
String value = ds.getValue(String.class);
Log.d("Tag", "Value is" + value);
}
}
JSON:
{
"Member" : {
"-LhKJVG1Tj2628sHPg4D" : {
"age" : "21",
"name" : "Gagan",
"nickname" : "Gaggi"`enter code here`
},
"-LhKKaNFnPrrh1bQNPfH" : {
"age" : "18",
"name" : "Jashan",
"nickname" : "Jassi"
}
}
}
You cannot call getValue with String.class because it does not meet the criteria of the method call.
From the documentation
public T getValue(Class valueType)
This method is used to marshall the data contained in this snapshot into a class of your choosing. The class must fit 2 simple constraints:
The class must have a default constructor that takes no arguments
The class must define public getters for the properties to be assigned. Properties without a public getter will be set to their default value when an instance is deserialized
An example class might look like:
class Message {
private String author;
private String text;
private Message() {}
public Message(String author, String text) {
this.author = author;
this.text = text;
}
public String getAuthor() {
return author;
}
public String getText() {
return text;
}
}
// Later
Message m = snapshot.getValue(Message.class);
You can use String class
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot ds : dataSnapshot.getChildren()) {
String name= ds.child("name").getValue(String.class);
String age= ds.child("age").getValue(String.class);
//and similar for others
Log.d("TAG", email + " / " + name);
}
}
I have list of object store in single document in Firestore. On my android side i am not able to fetch list of object and their inner data.
Here is code i am trying to fetch data
CollectionReference mCollectionReference = FirebaseFirestore.getInstance().collection("Categories");
mCollectionReference.document("Dinner Dishes").get().addOnSuccessListener(new OnSuccessListener<DocumentSnapshot>() {
#Override
public void onSuccess(DocumentSnapshot documentSnapshot) {
Collection<Object> objectMap = documentSnapshot.getData().values();
for(Object result:objectMap){
Sample obj = Sample.class.cast(result);
HashMap<String, String> pic = obj.getPic();
HashMap<String, String> name = obj.getName();
}
}
});
I need list of object i upload on Firestore in single document
My Model Class:
public class Sample {
private String name;
private String pic;
public Sample() {
}
public String getName() {
return name;
}
public String getPic() {
return pic;
}
}
You can convert it to a java object, if that is how you saved it?
ObjectType myObject = document.toObject(ObjectType.class);
I have a custom list adapter that has many methods that query the database and add data to different java objects or lists.
code to consider in adapter as follows: -
static class ViewHolder {
ArrayList<String> imgUrls;
//other variables;
}
then initiated it in getView method as:-
public View getView(#params) {
holder.imgUrls = new ArrayList<>();
}
//i have a method that query and retrieve data from firebase as follows:-
public void getPhoto(final ViewHolder holder) {
Query query = reference
.child(mContext.getString(R.string.dbname_collections))
.child(holder.collection.getCollection_id())
.child("photo_url");
query.keepSynced(true);
query.addListenerForSingleValueEvent(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for (DataSnapshot singleSnapshot : dataSnapshot.getChildren()) {
imgUrl = singleSnapshot.getValue(String.class);
Log.d(TAG, "onDataChange: imgUrl: " + imgUrl);
holder.imgUrls.add(imgUrl);
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
Log.d(TAG, "getPhoto: list with values " + holder.imgUrls);
}
My database in firebase console look like this:-
{
"collections": {
"-L9nNSyF7ZhEqpvmPo0Z": {
"caption": "jakhaha",
"collection_id": "-L9nNSyF7ZhEqpvmPo0Z",
"date_created": "2018-04-11T11:55:57Z",
"photo_url": [
"https://firebasestorage.googleapis.com/v0/b/backbench-72a47.appspot.com/o/collection%2Fusers%2FHb8ORoozQ3WhyxjaSyqazjHypkf2%2F2018-04-11T11%3A55%3A57Z%2Fphoto0?alt=media&token=08fdb740-9b16-455b-83ec-bfcec1455834",
"https://firebasestorage.googleapis.com/v0/b/backbench-72a47.appspot.com/o/collection%2Fusers%2FHb8ORoozQ3WhyxjaSyqazjHypkf2%2F2018-04-11T11%3A55%3A57Z%2Fphoto1?alt=media&token=eeca4b10-0729-4ca9-be18-c31d054add19",
"https://firebasestorage.googleapis.com/v0/b/backbench-72a47.appspot.com/o/collection%2Fusers%2FHb8ORoozQ3WhyxjaSyqazjHypkf2%2F2018-04-11T11%3A55%3A57Z%2Fphoto2?alt=media&token=b33c97b0-c2bf-4199-bef0-b498f505a678"
],
//this are the imageUrls i want to retrieve as a arrylist
"tags": "#NoTags",
"user_id": "Hb8ORoozQ3WhyxjaSyqazjHypkf2"
}
}
}
in my firebase model class :-
public class Collection implements Parcelable {
//properties for photo (*case sensitive*)
private String caption;
private String date_created;
private String collection_id;
private String user_id;
private String tags;
//list of likes
private List<String> photo_url;
private List<Like> likes;
private List<Comment> comments;
public Collection() {
}
//constructor..getter setters etc...
}
in my log console i see that values of imgUrl are fatched
04-11 20:35:03.992 21269-21269/com.backbenchers.administrator.instaclone D/CollectionListAdapter: onDataChange: imgUrl://url of image 1
onDataChange: imgUrl: url of image 2
onDataChange: imgUrl: ...image 3
but it shows list as null or [] :-
D/CollectionListAdapter: getPhoto: list is with values : []
"I want to fetch this firebase data and add it to an arraylist.."
what is wrong ??
Thanks!
We are trying to access the array of object that placed inside a map.
Can any one guide us to get length of the array as well as fetching each element from the list. Sample map object given bellow.
{
storeId = 1,
ShipToStreetLine1 = test 123,
ShipToCity = Seattle,
OrderDetails = [{
distributor_name = SS,
product_name = HORN 80897 AM GUN 300BO 125 HP 50/10
}]
}
We need to get the size of orderDetails array and if data present, then I want to fetch product_name.
You can try this:
Create a POJO which is type of what you are getting in orderDetails
Like
public class OrderDetailElement{
private String distributor_name;
private String product_name;
public String getDistributor_name() {
return distributor_name;
}
public void setDistributor_name(String distributor_name) {
this.distributor_name = distributor_name;
}
public String getProduct_name() {
return product_name;
}
public void setProduct_name(String product_name) {
this.product_name = product_name;
}
}
in your logic class you can do is
ArrayList<OrderDetailElement> orderDetails = yourMap.get("OrderDetails");
List<String> products = new ArrayList<String>();
if (orderDetails.size() > 0) {
for (OrderDetailElement orderDetailElement : orderDetails) {
products.add(orderDetailElement.getProduct_name());
}
}
I'm receiving these errors when I tried to populate a list view with firebase adapter using firebase UI
com.google.firebase.database.DatabaseException: Failed to convert
value of type java.util.HashMap to String
com.google.firebase.database.DatabaseException: Class
java.util.HashMap has generic type parameters, please use
GenericTypeIndicator instead
Here Is the code
DatabaseReference ref = FirebaseDatabase.getInstance().getReference();
DatabaseReference a = ref.child("info");
final FirebaseListAdapter<String> adapter =
new FirebaseListAdapter<String>(this,String.class,android.R.layout.simple_list_item_1,a) {
#Override
protected void populateView(View v, String model, int position) {
TextView text = (TextView) findViewById(android.R.id.text1);
text.setText(model);
}
here is an example of json data
"info" : {
"KSTUJILdwPN305Fs7ujhga4knlG3" : {
"File Info" : {
"-JFRkA855rfOU7GtcK4" : {
"Name" : "John",
"Adress" : "Test Adress",
"Favourite_food" : "Bread",
},
info node does not refer to your data model. It may contain children nodes. So to reach the model, you should use a reference like this.
DatabaseReference a = ref.child("info").child(info_id).child("File Info").child(file_id);
and you should have a FileInfo model instead of String model to use in
populateView(View v, FileInfo model, int position):
and model
public class FileInfo {
private String Name;
private String Adress;
private String Favourite_food;
public FileInfo() {
}
public FileInfo(String Name, String Adress, String Favourite_food) {
this.Name = Name;
this.Adress = Adress;
this.Favourite_food = Favourite_food;
}
public String getName() {
return Name;
}
public void setName(String Name) {
this.Name = Name;
}
public String getAdress() {
return Adress;
}
public void setAdress(String Adress) {
this.Adress = Adress;
}
public String getFavourite_food() {
return Favourite_food;
}
public void setFavourite_food(String Favourite_food) {
this.Favourite_food = Favourite_food;
}
}
final FirebaseListAdapter<String> adapter = new FirebaseListAdapter<String>(this,String.class,android.R.layout.simple_list_item_1,a)
public FirebaseListAdapter(Activity activity,
java.lang.Class<T> modelClass,
int modelLayout,
com.firebase.client.Firebase ref)
modelClass - Firebase will marshall the data at a location into an instance of a class that you provide
replace the constructor's 2nd parameter (String.class) with a POJO with the fields from info (name, address, favouriteFood)
FirebaseListAdapter
Edit:
You should also use getters in the populateView method