Re: [eclipselink-users] Dynamic Schemas

[James Sutherland <jamesssss@xxxxxxxxx>]

There are pre/postExecuteQuery events on the SessionEventManager (these are
session events, not descriptor events).

You might be better off handling this complexity in your application/model
instead of trying to automate it.  i.e. have several different classes or
subclasses mapped to each schema, or several different sessions/persistence
contexts, and query the desired one directly.

EclipseLink does have some features, such as TABLE_PER_CLASS inheritance,
and VariableOneToOne mappings which may be of some use.



bryans wrote:
> 
> Rather than start digging without knowing where to make changes, i figured
> i'd ask my question to the developers who created the framework.
> 
> I have an entity that's mapped to a table. This table actually exists in
> multiple database schemas, they are identical in every way. We use a
> look-up table to determine which schema to use. The look-up value is an
> attribute of the entity.
> 
> I need to be able to put in some kind of logic into an entity SQL
> generating stack to change the schema based on that look-up. I know the
> look-up logic, but my question is where to manipulate the SQL generation.
> 
> I thought about manipulating the Descriptor's qualifier prior to SQL
> generation, however i found some thing somewhere that said once the
> Descriptor is created for an entity it shouldn't be modified (i assume
> threading issues).
> 
> So my next thought was to build in some entity listeners to manipulate the
> SQL during the call stack. I haven't done that yet because: there's no
> pre-read query listener. There are pre/post handlers for create, update,
> and delete, but not read...
> 
> Suggestions on how i should go about my task? (And why isn't there a
> pre-load listener?)
> 
> -B
> 


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http://wiki.eclipse.org/User:James.sutherland.oracle.com James Sutherland 
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