Re: [GDL2] custom class creation

[David Ayers]

Hello Blake

Blake Nicholson schrieb:
> (Note: I originally sent this to help-gnustep, but my message neither 
> went through nor bounced.  I apologize in advance if people end up 
> receiving duplicates.)

I, for one, didn't receive it.

>  From what class should custom enterprise objects inherit, NSObject or 
> EOGenericRecord?

Well technically both should work.

>  I've tried both ways and have not been successful 
> running the following code snippet:
>
> job = [[ESJob alloc] init];
> [job setStyle:8];
> [ec insertObject:job];
> [ec saveChanges];
> NSLog(@"%@", [jobDS fetchObjects]);
>
> where ec is my EOEditingContext and jobDS is an EODatabaseDataSource for 
> the ESJob entity (I followed the setup in the GDL2 examples).

It's been a while... where exactly did we hide these examples?   They 
don't seem to be in svn.  I remember that some old examples were 
incorrect due to buggy GDL2 implementation at the time.

>  When I 
> inherit from EOGenericRecord, the code fails when saving changes and 
> gives the output I copied in below.  When ESJob inherits from NSObject, 
> the code fails when I attempt to fetch the objects (Bus error).
>
> I am running OS X (Leopard) and am using the sources from svn (the 
> revision I'm working with is 26179 for make, baseadd, and gdl2).  My 
> library combo is apple-apple-apple.  I've included the interface and 
> implementation files for my ESJob class that inherits from NSObject 
> below the error output I've received.  If you need any other info, 
> please let me know.

[snip]

> *** Error when ESJob inherits from EOGenericRecord ***
> 2008-03-03 01:35:52.710 test[33391:10b] *** Assertion failure in 
> -[EODatabase entityForObject:], EODatabase.m:321
> 2008-03-03 01:35:52.734 test[33391:10b] No object entity name for object 
> <ESJob 0x42f530 : classDescription=(null)
> values={
> }> of class ESJob (No object entity name for object <ESJob 0x42f530 : 
> classDescription=(null)
> values={
> }> of class ESJob)

This seems to indicate that the EOModel containing the EOEntity for 
ESJob wasn't found.  Maybe you could send me the eomodel files (or a 
small project tarball) privately and I can have a look this evening.

In general we create new instances of enterprise objects with:
<code compiled="NO"; tested="NO";>

  EOEntity *entity = [[EOModelGroup defaultGroup] entityNamed: @"ESJob"];
  EOClassDescription *cd = [entity classDescriptionForInstances];
  job = [cd createInstanceWithEditingContext: ec
            globalID: nil
            zone: NULL];
  [ec insertObject:job];
  [ec saveChanges];

</code>

This will insure the invocation of all the initialization methods which 
are part of the GDL2 API are invoked.

WRT inheriting from NSObject vs. EOGenericReocord:

GDL2 tries to replace some of the KVC methods at runtime to mirror the 
semantics of WebObjects 4.5.  This method/category swiziling was 
developed with GNU runtime and gnustep-base.  AFAIR we had /some/ 
success on OS X with the Apple runtime and Foundation at the time.  But 
that's a few years back so I can easily imagine that either

a) we didn't / couldn't catch all the tricky semantics
b) we are subject to bit-rot.

Cheers,
David