This is an upper level design question associated with how to best
generate a unique value using Cayenne and MySQL.
Step 1:
I have an existent Entity with a primary key (oid). Per the Cayenne-
recommended best practices I am avoiding direct access of this primary
key and have created another attribute (orderID) that must be unique.
So upon doing my Cayenne homework I read that the standard behavior in
the DBMS model and the ORM model is to support only one auto-generated
column and this is typically the PK column not related to my data
abstraction.
Step 2:
So then I thought, well I will just use the MySQL "MAX()" function,
find the max value, increment and voila I have generate my own unique
number. When I tried to implement this design I ran into problems with
SQLTemplate query attempting to bind the result of MAX(orderID) to an
existent data object.
Step 3:
I guess I could always execute a "select *" on the entity and find the
max attribute-value with a "for" loop, but that seems kind of
Neanderthal. OK, so I am now thinking someone must have solved this
sort of design issue before I bumped into it. What is the best way to
solve this issue using Cayenne design patterns?
Thanks,
Joe
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