Knowing that there are some frameworks to do it in real-world situation. As I learning from scratch, I wonder is that possible to create pure MongoDB DAO as a layer on top of the Service
class to do CRUD
operation that also facilitate other DAO use it?
For example, below is my Generic DAO class to operate CRUD process.
public interface IGenericDAO<T> {
public T create(T t);
public T update(T t);
public T get(Object id);
public void delete(Object id);
public List<T> listAll();
public Long count();
}
Then, DAO class should implements its operations
public class UserDAO implements IGenericDAO<User> {
MongoDatabase database = dBUtils.getMongoDB();
MongoCollection <Document> userTbl = database.getCollection("User");
public UserDAO() {
super();
}
@Override
public User create(User user) {
return user;
}
// other CURD below
}
User Service class
public class UserService {
private UserDAO userDAO;
public UserService() {
}
public void listUser() {
// need to test
List<User> listUsers = userDAO.listAll();
}
public void create(User user) {
// this what I want to see. user is saved to db here
try {
MongoDatabase database = dBUtils.getMongoDB();
assert mdb != null;
// create or get collection
MongoCollection<User> userTbl = database.getCollection("Users", User.class);
User userDoc = new User();
userTbl.insertOne(userDoc);
} catch (Exception e) {
e.printStackTrace();
}
}
Having said that, I want to put MongoDB "layer" between the DAO and Service class to do the CRUD operation. I wonder is it necessary, otherwise, how to do it to help the UserService
with UserDAO
class?
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