How to update one field from all documents using POJO in Firestore?

Question

I have this Student POJO class:

public class Student {
    private String name, rollNumber;
    private boolean active;

    public Student() {
        //For Firebase
    }

    public Student(String name, String rollNumber, boolean active) {
        this.name = name;
        this.rollNumber = rollNumber;
        this.active = active;
    }

    public String getName() {
        return name;
    }

    public String getRollNumber() {
        return rollNumber;
    }

    public boolean isActive() {
        return active;
    }
}

This is my database:

student-xxxxx
   -students
       -uid
         - name
         - rollNumber
         - active

There are 100 students, some are active and some are not. I want to make all students not active.

Code:

db.collection("students").get().addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
    @Override
    public void onComplete(@NonNull Task<QuerySnapshot> task) {
        if (task.isSuccessful()) {
            for (DocumentSnapshot document : task.getResult()) {
                Student student = document.toObject(Student.class);
                // How to update???
            }
        }
    }
});

How to update active to false using POJO? Thanks!

Answer 1

You can solve this, in a very simple way. Beside the getter, you should also create a setter for your active property like this:

public void setActive(boolean active) {
    this.active = active;
}

Once you have created the setter, you can use it directly on your student object like this:

db.collection("students").get().addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
    @Override
    public void onComplete(@NonNull Task<QuerySnapshot> task) {
        if (task.isSuccessful()) {
            for (DocumentSnapshot document : task.getResult()) {
                Student student = document.toObject(Student.class);
                student.setActive(false); //Use the setter
                String id = document.getId();
                db.collection("students").document(id).set(student); //Set student object
            }
        }
    }
});

The result of this code would be to update the active property of all you student objects to false and set the updated object right on the corresponding reference.