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From "andrew cooke (JIRA)" <empire-db-...@incubator.apache.org>
Subject [jira] Created: (EMPIREDB-60) Cloning of columns is restricted to current class
Date Sun, 18 Oct 2009 17:32:31 GMT
Cloning of columns is restricted to current class
-------------------------------------------------

                 Key: EMPIREDB-60
                 URL: https://issues.apache.org/jira/browse/EMPIREDB-60
             Project: Empire-DB
          Issue Type: Bug
          Components: Core
    Affects Versions: empire-db-2.0.5-incubating
            Reporter: andrew cooke


[First, I must admit that this may be some weirdness related to Scala, but I don't see how]

The cloning of columns in DBTable runs through the fields of the current class (Line 104):

            Field[] fields = getClass().getDeclaredFields();

As far as I can see, this only lists fields for the current class (Javadoc for Java class,
see difference between getDeclaredFields and getFields)

Now maybe I am doing some evil coupling between database and the classes I am using to model
my domain, but I am using tables with a class hierarchy.  So, for example, a base class has
an ID column, then a subclass might add a VALUE column, etc.  This lets me place methods related
to commonly occurring columns in base classes.

Unfortunately, cloning tables then fails to work as expected (and I need cloning of tables
so that I can make queries that join a class with "itself").

The solution is to put the cloning code in a loop something like:

  Class clazz = getClass()
  while (clazz != DBTable.class) {
     ... cloning here
    clazz = clazz.getSuperClass()
  }

Which I have done (I already need to override this clone method to use Scala accessors) and
which fixes my problems.

Apologies if I have misunderstood or am misusing the library.



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