I am thinking of redefining one of the mapping assumptions that was in Cayenne 
since day one. In 3.2 I want to move attribute java type from ObjAttribute to 
DbAttribute. The goal of this change is to improve consistency of the runtime 
model. Current separation of Java and DB attribute types causes a whole class 
of bugs and a whole class of hacks in the framework.

E.g.:

1. Unrecognized non-standard type mapping. This one is discussed at the moment 
on the user list [1]. I suspect it has nothing to do with "custom" types, but 
rather with non-JDBC default mapping of DB data to Java, regardless of the Java 
type.

2. Hacks to recognize non-standard type mapping. When creating a DataRow, 
Cayenne would try to guess which ObjEntities might use this DataRow, and 
populate DataRows with values corresponding to the ObjAttribute type 
definitions. This clearly breaks layer separation - lower layers have to know 
too much about the higher layers of the stack. Besides it doesn't always work 
anyways - see #3.

3. Extra mapping "flexibility" that doesn't really work. We had past Jiras when 
the same column is mapped to different Java types in 2 different subclasses, 
creating a mess in subclass-agnostic DataRows.

This is not a full list of problems, but gives you some idea. I am hoping the 
suggested change would tie things up and leave no space for ambiguities.

Comments?

Andrus

[1] http://markmail.org/message/6bs2suislyfp3apk

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