One-to-many relationship with misleading back reference

[Danilo Tuler]

Hi,

I have an *unidirectional* one-to-many relationship like this:

class Group {
  static hasMany = [items: Item]
}

class Item {
  Group subgroup

  static constraints = {
    subgroup nullable: true
  }
}


def group = new Group().save()
def item = new Item().save()

group.addToItems(item)
group.save()

this is setting item.subgroup to group.
But this is not my intention.
Can I avoid addTo setting the back-reference?

Thanks,
Danilo

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[Ian Roberts]

On 20/07/2012 07:02, Danilo Tuler wrote:
> Can I avoid addTo setting the back-reference?

I believe you can do this with

static mappedBy = [items:null]

on the Group side.

Ian

--
Ian Roberts               | Department of Computer Science
[hidden email]  | University of Sheffield, UK



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[Danilo Tuler]

Did not work...

2012/7/20 Ian Roberts <[hidden email]>:

> On 20/07/2012 07:02, Danilo Tuler wrote:
>> Can I avoid addTo setting the back-reference?
>
> I believe you can do this with
>
> static mappedBy = [items:null]
>
> on the Group side.
>
> Ian
>
> --
> Ian Roberts               | Department of Computer Science
> [hidden email]  | University of Sheffield, UK
>
>
>
> ---------------------------------------------------------------------
> To unsubscribe from this list, please visit:
>
>     http://xircles.codehaus.org/manage_email
>
>

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[Ian Roberts]

On 20/07/2012 15:48, Danilo Tuler wrote:
> Did not work...

Sorry, I was working from a memory of a past post about a similar
situation, but I misremembered:

http://grails.1312388.n4.nabble.com/grails-1-3-7-GORM-misinterpretation-of-nullable-reflective-many-to-one-relationship-possible-bug-tp4585805p4589361.html

That suggests it should be mappedBy = [items:'null'] (i.e. the string
n-u-l-l rather than null).

Ian

--
Ian Roberts               | Department of Computer Science
[hidden email]  | University of Sheffield, UK



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[Danilo Tuler]

> http://grails.1312388.n4.nabble.com/grails-1-3-7-GORM-misinterpretation-of-nullable-reflective-many-to-one-relationship-possible-bug-tp4585805p4589361.html
>
> That suggests it should be mappedBy = [items:'null'] (i.e. the string
> n-u-l-l rather than null).

No luck. I get this error:

context.ContextLoader Context initialization failed
org.springframework.beans.factory.BeanCreationException: Error
creating bean with name 'pluginManager' defined in ServletContext
resource [/WEB-INF/applicationContext.xml]: Invocation of init method
failed; nested exception is
org.codehaus.groovy.grails.exceptions.GrailsDomainException:
Non-existent mapping property [null] specified for property [items] in
class [class Group]
        at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
        at java.util.concurrent.FutureTask.run(FutureTask.java:138)
        at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
        at java.lang.Thread.run(Thread.java:680)
Caused by: org.codehaus.groovy.grails.exceptions.GrailsDomainException:
Non-existent mapping property [null] specified for property [items] in
class [class Group]
        ... 5 more

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[Matt Sheehan]

What if you implement your own addToItems method on Group?

On Fri, Jul 20, 2012 at 8:27 PM, Danilo Tuler <[hidden email]> wrote:

> http://grails.1312388.n4.nabble.com/grails-1-3-7-GORM-misinterpretation-of-nullable-reflective-many-to-one-relationship-possible-bug-tp4585805p4589361.html
>
> That suggests it should be mappedBy = [items:'null'] (i.e. the string
> n-u-l-l rather than null).

No luck. I get this error:

context.ContextLoader Context initialization failed
org.springframework.beans.factory.BeanCreationException: Error
creating bean with name 'pluginManager' defined in ServletContext
resource [/WEB-INF/applicationContext.xml]: Invocation of init method
failed; nested exception is
org.codehaus.groovy.grails.exceptions.GrailsDomainException:
Non-existent mapping property [null] specified for property [items] in
class [class Group]
        at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
        at java.util.concurrent.FutureTask.run(FutureTask.java:138)
        at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
        at java.lang.Thread.run(Thread.java:680)
Caused by: org.codehaus.groovy.grails.exceptions.GrailsDomainException:
Non-existent mapping property [null] specified for property [items] in
class [class Group]
        ... 5 more

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