[kforge-dev] Error in kforge trunk related to creation of trac service via web user interface

[John Bywater]

Rufus Pollock wrote:

> When I try to create a trac service via the web interfact I get the 
> following error:
>

Woops!


>> There's been an error:
>>

Sorry!


>> File
>> "/home/kforge/test.kforgeproject.com/system/lib/python/kforge/django/apps/kui/views/service.py", 
>>
>> line 131, in getManipulatedObjectRegister return
>> service.plugin.getExtnRegister()
>>
>> AttributeError: 'NoneType' object has no attribute 'plugin'
>
>
> Relevant method is:
>
>     def getManipulatedObjectRegister(self):
>         service = self.getAssociationObject()
>         return service.plugin.getExtnRegister()


Yes, something is broken.

>
> getAssociatedObject 


getAssociat-ION-Object :-) I think you looked at the right code though....

> is defined in dm.view.base.AbstractHasManyView where it is set to None 
> in the __init__ method. I can't see it being set anywhere else. John, 
> I know you wrote this section of the code so I wondered if you knew 
> what was going on here and what should be fixed (would be useful to 
> know what an associationObject was or was supposed to do -- some 
> documentation on that class might be useful ...).


Some more tests would also be useful. That method is in the 
ServiceExtnView, which I'll come back to. Firstly...


## Associate, Aquaintance, Associations ##

In OO terminology, an object can have be associated with another. The 
association is sometimes an object.

In KForge a Person can have an association with a Project. The 
association is called Member.  The Project is then an associated object 
or an aquaintance of the Person.

Likewise, a Service is an association between a Project and a Plugin.


## AbstractHasManyView ##

The abstract HasMany view is the base class for CRUDing the register of 
objects held by a domain object within a HasMany attribute.

The getAssociationObject() method is used to retrieve the object keyed 
by the hasManyKey (a string) in the domain object's HasMany attribute 
register.


## ServiceView ##

For Service views, you get a Service domain object by calling the 
getAssociationObject method. This happens a lot in the Service views.


## ServiceExtnView ##

The ServiceExtnView extends the Service view, and supportings CRUDing of 
service extentions, which is the mechanism to plugin the particular 
objects of plugin service instance into the domain model (such as the 
TracProject object which is needed to support associating a Trac Service 
with a Subversion Service).

As such, this view always expects that the Service object is available.

It isn't available. The service variable has a ref to None.


## Diagnosis ##

There is a problem with the trac Service object being located. Does it 
exist? Was it created with the previous page?  Ie if you click back to 
the Project read view and refresh, does the object appear? It so, there 
is something wrong with finding a new trac Service in that ServiceExtn view.

An exception reporting the non-existence of the Service object would be 
sufficient documentation for this error. Perhaps this could usefully be 
in a getService() method on the ServiceExtnView.


I'll try to replicate the problem. Will let you know what happens.

In the meantime, can you write a test to reveal this problem?

Regards,

John.