what is BUSINESS DELIGATE PATTERN,DAO,VO,DTO?
Answer Posted / kathiravan j
Let's say I have three tables:
Employee (contains employee_id, employee_name, and dept_id)
Department (contains dept_id, dept_name, loc_id)
Location (contains loc_id, location_name)
How deep do your classes go to replicate the data?
Do you do this...
public class Employee {
private int id;
private String name;
private int deptId; // just the id
// .. implementation details
}
or do you do this
public class Employee {
private int id;
private String name;
private Department dept; // all of the data
// .. implementation details
}
and so on and so on. Class Department has the same type of
problem. Does it hold just the id for location or a
variable class Location?
Should DAOs just fill in the id (keys) so it is up to the
application using the DAOs to get the Employee class, then
the Department class, and the the Location class like:
Employee emp = EmployeDAO.getEmployee(1);
Department dept = DepartmentDAO.getDepartment(emp.getDeptId
());
Location loc = LocationDAO.getLocation(dept.getLocId());
System.out.println(emp.getEmpName() + " works in " +
loc.getLocationName());
or
Employee emp = EmployeDAO.getEmployee(1);
System.out.println(emp.getEmpName() + " works in " +
emp.getDept().getLoc().getLocationName());
Now this is just a simple example, but where do you draw
the line? It's possible to go on and on and on and cycle
back to employee... Taking another approach to the same
question...Say I have an employee_type table having values
of fulltime, parttime, etc. Whay do you store in the
employee class now? Just a String with the value of the
type or the key to the employee_type table? Is it
application dependent?
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