[MacRuby-devel] problems implementing a NSEntityMigrationPolicy? (fixed)

[Michael Johnston]

Actually this is working for me now. I did have a bug in my original  
migration policy, and at some point in my regression I changed  
something which resulted in my migration policy class not getting  
loaded by the application and didn't notice because the reported error  
was the same.


Cheerio,

Michael Johnston
lastobelus at mac.com




On 27-Jan-10, at 10:35 PM, Michael Johnston wrote:

> Hi,
>
> I'm having trouble implementing a NSEntityMigrationPolicy. Has  
> anyone used subclasses of NSEntityMigrationPolicy in macruby  
> successfully?
>
> I've narrowed it down to the empty macruby implementation, which  
> looks like this:
>
> {{{
>
> class V3RecipeIngredientToIngredient < NSEntityMigrationPolicy
>  def createDestinationInstancesForSourceInstance(source,  
> entityMapping:mapping, manager:manager, error:error)
>    return true
>  end
>
>  def createRelationshipsForDestinationInstance(dInstance,  
> entityMapping:mapping, manager:manager, error:error)
>    true
>  end
> end
>
> }}}
>
> when I run this (and do a addPersistentStoreWithType with  
> NSMigratePersistentStoresAutomaticallyOption) I get:
>
> #<Class:0x10145fc80>: An error occured during persistent store  
> migration.
> userInfo: {"NSUnderlyingException"=>#<_NSCoreDataException: 
> 0x8002d8840>}
>
> the _NSCoreDataException does not seem to have any message or other  
> chain of errors.
>
> the corresponding Objective C empty implementation works fine:
>
> {{{
> - (BOOL)createDestinationInstancesForSourceInstance: 
> (NSManagedObject*)source
>                                      entityMapping: 
> (NSEntityMapping*)mapping
>                                            manager: 
> (NSMigrationManager*)manager
>                                              error:(NSError**)error
> {
>  return YES;
> }
> }}}
>
> Is there any way to get more detail on how/why it is failing?
>
> Cheerio,
>
> Michael Johnston
> lastobelus at mac.com
>
>
>
>
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