FetchType.LAZY and number of records

[torakuma]

Hi-

I'd like to be able to get the number of child records (that are loaded lazily) for display in a data table without actually loading the records.  The children are loaded later when editing for performance reasons.

Here are the association and count properties in my parent entity

    @OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY)
    public List<Child> getChildren() {
        return children;
    }

    @Transient
    public int getNumChildren() {
        // Calling getChildren() to get this is overkill
        // when all I want is the count!
        return numChildren;
    }

My data table is using an EntityQuery object but I couldn't find a way to do it in there with JPQL.  It does, however, have a nice way to get the record count of the result list.  I just need the same thing for the association.

I then thought I could use @Formula in the property itself to be something like...

    @Transient
    @Formula(value="select Child child from child where child.fk=#{parent.id}")
    public int getNumChildren() {
        return numChildren;
    }

It seems as though my @Formula is being ignored.  I can put garbage in the value (i.e. value="lksajlksdfjksf") and I don't get an error in seam.  I'm new to @Formula so I may be messing this up.

Could someone show me how to get the record count of an association (without calling the child getter) when using EntityQuery?

Thanks!

[bravocharlie.seam.signup.benny.me.uk]

You could try using Hibernate extra-lazy collections.  I believe calling .size() does a COUNT() rather than actually fetch all the records.

   @LazyCollection(LazyCollectionOption.EXTRA)      

Have a search on extra lazy collections

[luxspes]

How can I find the size of a collection without initializing it?

[torakuma]

Oh the extra-lazy thing is just what I was after.  Thanks!