How to parse Object of Map<String, Object> returned from documentSnapshot.getData() of Google Cloud Firestore into a POJO?

Question

documentSnapshot.getData() method of Cloud Firestore returns a Map< String, Object >. My db structure looks like below:

Now I have a POJO as below:

public class Plan {

    private ArrayList<String> items;
    private String name;
    private int price;
    private int years;

    public Plan() {
    }

    public Plan(ArrayList<String> items, String name, int price, int years) {
        this.items = items;
        this.name = name;
        this.price = price;
        this.years = years;
    }

    public List<String> getItems() {
        return items;
    }

    public void setItems(ArrayList<String> items) {
        this.items = items;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getPrice() {
        return price;
    }

    public void setPrice(int price) {
        this.price = price;
    }

    public int getYears() {
        return years;
    }

    public void setYears(int years) {
        this.years = years;
    }
}

As you see, all I want is a list of Object from the Map< String, Object > returned from documentSnapshot.getData() method. The String, ie, the key part, has to be ignored. I don't want to use keys to extract from Map as I want the algorithm to dynamically create a list of all plans (POJO) irrespective of the number of key-value pairs in the map.

Below is the code I'm using:

documentReference.get().addOnSuccessListener(new OnSuccessListener<DocumentSnapshot>() {
            @Override
            public void onSuccess(DocumentSnapshot documentSnapshot) {
                if (documentSnapshot.exists()) {
                    Map<String, Object> planMap = documentSnapshot.getData();
                    // how to parse the Object inside Map<String, Object> above to POJO Plan.class here
                    }
                }
            }
        });

I tried many ways but I am unable to parse that Object into my POJO. Please help. Thanks in advance.

Answer 1

The best way is, you should use the same POJO class that you were using to save the data. As it is a complex class and has object of Plan class so if you use that one it will be better. Let your original class name is Familiy_pack.

documentReference.get().addOnSuccessListener(new OnSuccessListener<DocumentSnapshot>() {
            @Override
            public void onSuccess(DocumentSnapshot documentSnapshot) {
                if (documentSnapshot.exists()) {
                   Family_pack f = documentSnapshots.toObject(Family_pack .class);


                    }
                }
            }
        });

Now, use can easily get the values from Plan object.

Answer 2

Update: Refer Convert DocumentSnapshot Data to List as you want list of object

Official documentations says

 <T> T toObject(Class<T> valueType) - 
 Returns the contents of the document converted to a POJO or null if the document doesn't exist.

so try

Plan plan = documentSnapshots.toObject(Plan.class);

Ref - https://firebase.google.com/docs/reference/android/com/google/firebase/firestore/DocumentSnapshot

Answer 3

try QuerySnapshot instead of DocumentSnapshot :

documentReference.get().addOnSuccessListener(new OnSuccessListener<QuerySnapshot>() {
            @Override
            public void onSuccess(QuerySnapshot documentSnapshot) {
                if (documentSnapshots.isEmpty()) {
                    Log.d(TAG, "onSuccess: LIST EMPTY");
                    return;
                } else {
                    // Convert the whole Query Snapshot to a list
                    // of objects directly! No need to fetch each
                    // document.
                    List<Plan> plans = documentSnapshot.toObjects(Plan.class);   

                    // Add all to your list
                    mArrayList.addAll(types);
                    Log.d(TAG, "onSuccess: " + mArrayList);
                }
            }
        });