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From Mark Lowe <mark.l...@talk21.com>
Subject Re: Best Practice: Dealing with null inner objects within forms
Date Wed, 07 Jan 2004 18:58:24 GMT
I do this for addresses and such like, like this

public class Parent {
	
	private Address address;

	public Parent() {
		this.address = new Address();
	}
..

not sure if it best practice or not but makes sense to me.


On 7 Jan 2004, at 19:43, David Erickson wrote:

> Ok well I've been fighting this problem for months now and have never 
> really
> figured out the best way to deal with it.  I'll give a short 
> description
> hopefully it makes sense:
>
> public class Parent {
>     private String firstname;
>     private String lastname;
>     private Address address;
>    .. getters/setters etc.
> }
>
> Ok now my form object basically just has a getter/setter for a Parenty
> object.
>
> Within my jsp I want to use html:text elements for parent.firstname,
> parent.lastname, AND parent.address.street, parent.address.city,
> parent.address.state, etc.  Now the problem is address has the 
> potential to
> be loaded as null from the database if an address record is not tied 
> to the
> parent.  So in that case my jsp will throw a null pointer exception 
> because
> it tried to initialize the text element from a null'd variable member. 
>  But
> even if there is no record for that I want to be able to edit the 
> field and
> add one if its submitted.  This doesn't pose a problem for
> firstname/lastname because the parent object will never be null.
>
> The alternatives that I can see to solve this:
> 1) Use logic:notEmpty tags to display the textbox as long as there is a
> record, but if theres not the user won't be able to edit on that page, 
> so
> that doesn't really solve the problem
> 2) Within my parent object in its constructor initialize any member 
> object.
> IE:
>        public Parent () {
>          address = new Address()
>        }
> 3) Within the form's constructor make sure all of its member variables
> variables are non null. IE:
>       public myActionForm() {
>         parent.setAddress(new Address());
>       }
>       I don't like this though because that requires me to edit the 
> form
> everytime I change ANY of the objects contained therein.
>
> 4) ??
>
> I hope that was clear.. any alternatives or what is everyone else 
> doing to
> deal with this problem?
> Thanks,
> David
>
>
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