Hello!

I've got trouble with lazy @ManyToOne and @OneToOne: I can't get it lazy!
The childre are lazy indeed, but parent and data are loaded eagerly.
(the commented code has no effect)


@Entity
@Table(name = "NODE_TABLE")
public final class Node {

...
@ManyToOne(/* fetch = FetchType.LAZY */)
@Column(name = "PARENT_ID")
@Index(name = "NODE_PARENT_INDEX", columnNames = { "PARENT_ID" })
public Node getParent() {
return parent;
}

@OneToMany(mappedBy = "parent",/* fetch = FetchType.LAZY*/, cascade = CascadeType.ALL)
@OrderBy("name")
protected Set<Node> getChildrenInternal() {
return childrenInternal;
}
...
@OneToOne(fetch = FetchType.LAZY)
public Data getData() {
return data;
}
}


Please, any help! I need the data lazy because it's it's very heavy!

Thanks!

@ManyToOne(/* fetch = FetchType.LAZY */)
@Column(name = "PARENT_ID")
@Index(name = "NODE_PARENT_INDEX", columnNames = { "PARENT_ID" })
public Node getParent() {
return parent;
}

What if you decomment it or set it to fetch=FetchType.EAGER? on the JSR-220 spec it says FetchType.EAGER is the default (anybody correct me if I am wrong).

Alessio Pace.

Hi!
You seem to get me wrong: commenting or uncommenting the code gives the SAME result: no lazy (eager). So again: the problem is that I can't get it lazy even when lazy strategy IS specified...

Michael.

I was able to make the @OneToOne lazy:
the trick is to declare the dependant entity as proxyable like this:

@Entity
@Proxy(lazy=true)
class Data {...}

And, ofcource, set @OneToOne(fetch = FetchType.LAZY)
Looks like just setting fetch = FetchType.LAZY works only for collections. In this case it just creates a collection proxy. But in case of @xxxToOne an entity must be proxied. Looks like we just must allow it being proxied explicitly...


But I can't still make the @ManyToOne sideof the relation be lazy with this approach. May be the problem is that I have bidi one-to-many with self (the same entity) and the same entity is at the same time the "one" and "many" side of relation ... Currently I'm trying:

@Entity
@Proxy(lazy=true)
@Table(name = "NODE_TABLE")
public final class Node {

...
// lazy: PROBLEM, always eager
@ManyToOne( fetch = FetchType.LAZY )
@Column(name = "PARENT_ID")
@Index(name = "NODE_PARENT_INDEX", columnNames = { "PARENT_ID" })
public Node getParent() {
return parent;
}

// lazy collection: ok
@OneToMany(mappedBy = "parent", fetch = FetchType.LAZY, cascade = CascadeType.ALL)
@OrderBy("name")
protected Set<Node> getChildrenInternal() {
return childrenInternal;
}
...

// lazy: ok
@OneToOne(fetch = FetchType.LAZY)
public Data getData() {
return data;
}
}


@Entity
@Proxy(lazy=true)
class Data {...}

Still hoping... :-)
Thanks in advance,
Michael.

proxy = true is the default, so @ManyToOne(fetch=LAZY) and @ManyToOne(fetch=LAZY, optional=false)
will work out of the box, note the optional=false. There is an explaination in the wiki cummunity area on why an one-to-one cannot be lazy unless constrained

Emmanuel, how can I do a "constrained" relation with annotations?

@OneToOne(optional=false)

I guess it would be cool to have that in the annotation reference doc as well

We have found similar behavior when specifying a @ManyToOne with a @JoinColumn on a non-primary key (alternate key) referencedColumnName.



Our other uses of the @ManyToOne with LAZY fetch type work fine. Is there a workaround for this?

To work around that, you need to mark the association as lazy no proxy and use bytecode enhanced classes

I have not been able to find the annotation to mark the association as no-proxy. The fetch variable allows only LAZY or EAGER.

Would I have to use an hbm config to set this? If so, is it possible to only have that in my hbm configuration and not the rest of the metadata?

Make sure your class is not final.

Ramon Havermans