On 2/11/12 6:35am, Garth Keesler wrote:
Can the PK as specified in the DBEntity be different than the PK actually specified in 
the schema? I ask because I use DB-generated integer sequences as the primary keys which 
are never used in the software. The software uses an abbreviated form of the vendor name 
that is forced to be unique within the table. Would it make more sense to specify that 
the shortened name is the "real" PK in the definition of the DBEntity (which is 
hand-created, not extracted from the schema)? FYI, this column is also used in may 
foreign keys. Speaking of FKs, if I specify a relation in the DBEntity, should it share 
the name of the FK specified in the schema or are they unrelated?

I suggest that you map Cayenne's concept of the PK to the real PK since that is 
what you'll want to use for FK joins from other tables. Then just create a 
normal field for your vendor code and add validation to keep it unique. Making 
the vendor code the PK in any way is likely to cause lots of pain down the 
track when one of your vendors changes names and wants a new code.

One of the reasons Cayenne hides the PK from the Java entities by default is 
that it is almost never a good idea to expose the PK to users of the software.


Ari


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Aristedes Maniatis
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