Re: Design Question

On 21 Jul 2006, at 02:00, Michael Deninger wrote:

> I have some static data that I need to access from within an  
> EOGenericRecord. The data, unfortunately, is not in the DB (and  
> even if it were, creating a relationship to the entity would likely  
> not work for various reasons). The data is essentially a dictionary  
> of keys / values that describe the meaning of the coded values in  
> one of the database tables. E.G.
>
> Entity: PatientAllergy
> 	Attribute: AllergyCode
>
> where AllergyCode is some number (say 83). The meaning of that  
> number is in this dictionary (e.g. value = 83, description =  
> "penicillins")
>
> What is the best way to accomplish this? I have considered the  
> following:
>
> 1) read this dictionary into my Application object at startup.  
> Sounds great, but I cannot figure out how to access EOApplication  
> from an EOGenericRecord

Application application = (Application)Application.application();

Works from anywhere.

> 2) read this dictionary form disk into each EOGenericRecord at the  
> time it is created. I think that this would work, but it creates a  
> lot of unnecessary repetition of data.

Think classes - I presume that you are using a subclass of  
EOGenericRecord, and not EOGenericRecord itself.  Load the table on  
first request, as a static method within the appropriate class.

> 3) hard-code the dictionary into an abstract class extending  
> EOGenericRecord and have the Entity inherit from it.

This seems a little awkward to me.

You could create a class for the sole purpose of holding the values,  
as Ian suggests, but that strikes me as proliferation of objects.  On  
the whole, I would prefer to implement it as a static method of your  
entity class.

Paul