How to get userID by user Email Firebase android?

Question

Given a email address, is it possbile to get userID of a person? For example,

If I have a variable email that has email of the person. Can I get their ID by doing so

Answer 1

I had the same problem, which I solved by creating a new attribute to the model class whose data you want to access from another account.

As given below my model class has 5 attributes now. Initially it was only the first four.

public class User {

    public String id;
    public String name;
    public String email;
    public String role;
    public String uid;

    public User() {
    }

    public User(String id, String name, String email, String role, String uid) {
        this.id = id;
        this.name = name;
        this.email = email;
        this.role = role;
        this.uid = uid;
    }

    public String getId() {
        return id;
    }

    public String getName() {
        return name;
    }

    public String getEmail() {
        return email;
    }

    public String getRole() {
        return role;
    }

    public String getUid() {
        return uid;
    }

    public void setId(String id) {
        this.id = id;
    }


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

    public void setEmail(String email) {
        this.email = email;
    }

    public void setRole(String role) {
        this.role = role;
    }

    public void setUid(String uid) {
        this.uid = uid;
    }

}

In this class I had not put the uid attribute before. So, when I am signed in, I don't have the access to uid of another account. That is why I changed the model class as given above, and now I am able to access any data just by using any other parameter to check for equality.

For example,

mRef.addValueEventListener(new ValueEventListener() {
        private String role;

        @Override
        public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
            for(DataSnapshot snapshot: dataSnapshot.getChildren()){
                User user = snapshot.getValue(User.class);

                role = user.getRole();
                if(role!=null){
                    if(role.equals("student")){
                        STUDENT_LIST.add(user);
                    }
                }
            }
        }
        @Override
        public void onCancelled(@NonNull DatabaseError databaseError) {}
    });

Here you can see I am taking all the users who are students, whose values can be accessed using the uid that was added to the above model class, from another signed in account.