Should we inherit an actionForm

[Nakata kokuyo]

Good day,

i have two DB tables named "inv_header" and "inv_details"

inv_header:

invoice_id
invoice_date

inv_details:

invoice_id
invoice_qty

so in ActionForm , i make it details class inherit header class, is that any cons if i do this ?

 
public class Inv_header extends ActionForm
{
   invoice_id
   invoice_date
 
}
 
public class Inv_details extends Inv_header
{
 
   invoice_qty
 
}
 

thank you for guidance

[Merrill Higginson]

I don't see any down side to having one ActionForm inherit from another. I will caution you not to "overthink" ActionForms, though. They're just simple JavaBeans that match the data in a JSP page. I wouldn't recommend devising elaborate inheritance structures for them.

[Nakata kokuyo]

hi merill ,

i may use the following code to get all the data in table

BeanHandler beanList = new BeanHandler(Inv_details.class);
rsList = (Inv_details) beanList.handle(rs);

BeanHandler is from apache common utility, would it be heavy to carry if we have many header fields where the resultset return only Inv_details data but if Inv_details inherit the Inv_Header, it will have extra fields unnecessary inv_header fields

[Brent Sterling]

I would say that from an object oriented design view your use of inheritance seems to be wrong...at least as far as I am guessing at the relationship. Try to apply the "is a" rule to your inheritance. The class Dog can inherit from Mammal because "Dog is a Mammal". Is this true..."Invoice Details is an Invoice Header"? If you mean that you have one Invoice that has multiple Detail records then I would say that your Header class should contain a collection/list/array of Detail objects. You could also have your Detail class contain a reference to the Header class but I would not model this relationship with inheritance.

- Brent