I tried to make the question smaller, but I could not make it smaller :(
I have 2 entities and this is how they are related:
Collection (1) ----> (n) Item
Item (0 or 1) -----> (n) Item
i.e. each Item is related to a Collection. Further each Item can have 0 or more children Item. In case there is a child Item, the child Item will have a non-null parent_item_id;
Tables:
Collections
collection_id raw
Items
item_id raw
collection_id raw
parent_item_id raw
Mappings :
class Collections
{
@Id @Column("collection_id")
String id;
@OneToMany(fetch=FetchType.EAGER, cascadeType.ALL, mappedBy="collection")
List<Items> items;
}
class Items
{
@Id @Column("item_id")
String id;
@ManyToOne(optional=false)
@JoinColumn(name="collection_id")
Collections collection;
@ManyToOne(optional=true)
@JoinColumn(name="parent_item_id")
Items parentItem;
}
Suppose I have created an object like this:
//Constructor parameters are the Ids.
Collections collection1 = new Collections("1234");
Items i1 = new Items("111");
Items i2 = new Items("222");
item1.parentItem = item2;
item1.collection = collection1;
item2.collection = collection1;
List<Items> listItems = new ArrayList<Items>(1);
listItems.add(item2);
collection1.items = listItems;
We have a Data Access Layer (DA) which is a wrapper around JPA with Hibernate. Next, I perform two operations:
Collections collection1 = DA.merge(collection1);
Collections collection2 = DA.find(collection1.id);
I would expect collection2.items.size() to return 2. But it returns 1. (PS : there are actually 2 items related to the collection1).
Can it be explained? Is it expected or is it a bug in DA? Does JPA cache the Collection?
Later, if in a different transaction, I try to fetch Collections collectionNew = DA.find("1234").items.size() it returns 2 (expected);
