Justin Forder wrote:
>
> [I am sending this to the EJBoss list as well as adding it to Bugzilla,
> because anyone trying to use CMP in jBoss2.0 will need to be aware of
> the problem and a workaround. It is Bug#21 in Bugzilla.]
>
> CONTEXT
>
> If you have custom finders, you have to define their SQL WHERE clauses
> in EJX. Parameters in these clauses are represented by numbers (zero-
> based) in braces, e.g.
>
> balance > {0}
>
> The number corresponds to the position of the parameter in the finder
> method's parameter list.
>
> PROBLEM
>
> jBoss uses java.text.MessageFormat to do the substitution of these
> placeholders (in org.jboss.ejb.plugins.jaws.JAWSPersistenceManager, in
> the findEntities() method).
>
> This bypasses the type-sensitive handling of SQL parameters defined by
> JAWSPersistenceManager.setParameter(), which is what
> JAWSPersistenceManager normally uses for setting parameters in
> PreparedStatements.
>
> The most obvious consequence is that String literal parameters are not
> getting the single quotes that SQL requires.
>
> WORKAROUND
>
> To work around this, you need to put single quotes around the
> placeholder - and because MessageFormat uses single quotes to escape
> braces (e.g. '{ ), you have to double them up. For example
>
> description = ''{0}''
>
> FIX
>
> Sun's J2EE RI currently uses ? as a placeholder, allowing the WHERE
> clause to be plugged straight in to a PreparedStatement. This does mean
> that the order of parameters in the WHERE clause has to match the order
> of parameters in the finder. (It doesn't, however, place any limit on
> the number of parameters... MessageFormat has a limit of ten.)
>
> I suggest that JAWS should change to use ?, and that users should be
> told they have to organise their finders and WHERE clauses to have the
> same order of parameters.
>
> If this is not acceptable, the {n} placeholders should have their order
> noted, before being replaced by ? characters in the SQL for the
> PreparedStatement. Then the finder parameter order can be transformed
> into the SQL parameter order before going into the normal process of
> setting parameters using JAWSPersistenceManager.setParameter().
Submit a diff and attach it to bugzilla, Rickard can accept/reject fix.
Sounds like a good idea,
kind regards
marc
>
> --
> Justin Forder
>
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