On Sat, Jul 08, 2000 at 04:53:29PM +0200, Leon Messerschmidt wrote:
> Hi
>
> There is some functionality which might be useful to the generated peer
> classes, but I might need some slight changes to the table/column mapping
> classes, so that columns know if they are used as foreign keys in other
> tables.
>
> My proposal is for 1:M relations: Basically the idea is that if a table
> (call it A) has a column that is used as a foreign key in another table
> (call it B) the A data object will have a method that does a query and
> return a vector with related B data objects. The other way round B will
> have a method that returns it's master A object.
Yes this is a great idea. I have some perl scripts that do something
similar, so it is certainly feasible.
I was planning to look at adding this functionality to NGMBT myself, but
I haven't had any time to look at it yet - so please go ahead :-)
> To avoid overhead and the unnecessary loading of objects from database the
> query is only done once the method is called. In other words only when A's
> getBobjects() method is called the query is actually executed and the B
> objects loaded. In fact these methods are merely utility methods that does
> queries for that particular table's relations for you...
Yes - I believe that lazy querying is the right way to go. Have you
thought about updating?
My current system has a setBobjectIds(int[] ids) to replace the set
mapped to. Then the data object has an int[] field for these ids - the
field starts out null, and if an array gets stored there when the object
is saved the new set mapped to gets persisted to the mapping table.
--
Sean Legassick
[EMAIL PROTECTED]
homo sum: humani nihil a me alienum puto
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