self-association - cannot access loading collection error

newreaders · **Joined:** Wed Sep 15, 2004 3:14 am **Posts:** 35

Hibernate version: 2.1.6

I am having a "cannot access loading collection" problem as per described in the Hibernate FAQs from the Forum.

http://www.hibernate.org/74.html#A28

From the answer, I have to create another setter (setParentFromApp) to set the parent object. How do I only sets the parent field in setParent()?

Is it something like this?

private setParent(Parent o) {
this.parent.setId = o.getId;
}

public setParentFromApp(Parent o) {
this.parent = o;
}

I have tried the solution described but so far it is not working. It gives me NullPointerException in setParent()

What can I do to fix this? Thanks

newreaders · **Joined:** Wed Sep 15, 2004 3:14 am **Posts:** 35

setParent() should be:

private setParent(Parent o) {
this.parent.setId(o.getId);
}

Dencel · **Joined:** Tue Jan 27, 2004 12:22 pm **Posts:** 103

If you don't have "access=field" attribute in the Hibernate Mapping file for the property "parent" it will always be null! Hibernate access the attribute with the appropiate get/setter.You methods should look like this:
GOOD

Code:

//<!-- Used by Hibernate to set the Parent object -->
public setParent(Parent o) { 
this.parent = o; 
} 

public setParentFromApp(Parent o) { 
this.parent = o; 
} 

ERROR

Code:

//<!-- Error code -->
private (can't be accessed by Hibernate) setParent(Parent o) { 
this.parent.id (ERROR: Parent is null) = o.getId(); 
} 

[/b]

newreaders · **Joined:** Wed Sep 15, 2004 3:14 am **Posts:** 35

So basically, I just have to add another setter (setParentFromApp()) and put access="field" in the Hiberante mapping file.

Quote:

have "access=field" attribute in the Hibernate Mapping file for the property "parent"

Is this how you define it?

Code:

<many-to-one
      name="parentCategory"
      class="Category"
      cascade="none"
      outer-join="false"
      update="true"
      insert="true"
      access="field"
      foreign-key="parentCategoryId_fk"
      column="parentCategoryId"
      unique="false"
/>

I did that and I still get "cannot access loading collection" when I try to get the size of the childCategories.

Thanks

Dencel · **Joined:** Tue Jan 27, 2004 12:22 pm **Posts:** 103

Remove the "access=field". it was meant hypothetical.

newreaders · **Joined:** Wed Sep 15, 2004 3:14 am **Posts:** 35

If I use the following code, I can't use cascade="all-delete-orphan" can I?

Quote:

//
public setParent(Parent o) {
this.parent = o;
}

public setParentFromApp(Parent o) {
this.parent = o;
}

I think I tried the above code and it was unsuccessful, I will try again.

Thanks

Dencel · **Joined:** Tue Jan 27, 2004 12:22 pm **Posts:** 103

I am sorry, I did not look at the FAQ, just corrected an error in you code.
Can you please supply some more information about what you are doing? Mapping and code between exception?

darksoul · **Joined:** Sun Dec 12, 2004 5:52 pm **Posts:** 9

setter\getter functions can have any access modifier.

see hibernate reference chapter 4 section 1.1:

Quote:

Properties need not be declared public - Hibernate can persist a property with a default, protected or private get / set pair.