Where is the best place(s) to handle entity relationships?

danz8086 · **Joined:** Tue Mar 02, 2004 6:17 pm **Posts:** 20

Hi,

I've been searching and reading posts and articles around this website, tring to decide whether I should implement all the relationship handling into my DAO or leave it to the business logic layer.

By relationship handling, I mean calling the stuff like addChild(), add Parent(), and deleteChild() etc.

My feeling is to include these in the DAO layer, because the associated objects are initialized (lazy or not) anyway through a single DAO method call.

But when considering things like a composition relationship, questions like "should I create the child from within the parent creation code?" got me into lost:

Any comments/suggestions?

Thanks,
Dan

christian · **Posted:** Thu Apr 15, 2004 7:17 am

I recommend handling relationships in additional methods in the domain model POJOs themself:

Code:

public void addChildCategory(Category childCategory) {
    if (childCategory == null)
        throw new IllegalArgumentException("Can't add a null child category.");
    if (childCategory.getParent() != null)
        childCategory.getParent().getChildCategories().remove(childCategory);
    childCategory.setParent(this);
    childCategories.add(childCategory);
}

anthony · **Posted:** Thu Apr 15, 2004 10:25 am

what about putting this usefull approach as a best pratice in the reference doc or wiki?

i even think that depending mapping (one to