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From "Al Le (JIRA)" <ibatis-...@incubator.apache.org>
Subject [jira] Commented: (IBATIS-37) Allow typeHandler class to implement TypeHandler interface
Date Thu, 06 Jan 2005 11:00:13 GMT
     [ http://issues.apache.org/jira/browse/IBATIS-37?page=comments#action_57344 ]
     
Al Le commented on IBATIS-37:
-----------------------------

Clinton,

as of iBatis 2.0.9, it seems that you added this functionality to SqlMapConfigParser but not
to SqlMapParser. In SqlMapParser.java, line 358, no check for TypeHandler is made.

I haven't verified this but rather found this out by code inspection (as I wanted to learn
how custom type hanling works in Ibatis). Hence I may be wrong.

> Allow typeHandler class to implement TypeHandler interface
> ----------------------------------------------------------
>
>          Key: IBATIS-37
>          URL: http://issues.apache.org/jira/browse/IBATIS-37
>      Project: iBatis for Java
>         Type: Improvement
>   Components: SQL Maps
>     Versions: 2.0.8
>     Reporter: Juergen Hoeller
>     Assignee: Clinton Begin
>      Fix For: 2.0.9

>
> Hi Clinton and team,
> We plan to provide BLOB/CLOB type handlers for iBATIS SQL Maps 2 in Spring, delegating
to Spring's LobHandler abstraction. I've checked out your new TypeHandler support, which looks
like a nice hook for this.
> Spring's LobHandler expects to work on PreparedStatements and ResultSets. For this reason,
the TypeHandlerCallback mechanism in SQL Maps cannot be used; we need to provide plain TypeHandler
implementations. I've already implemented such TypeHandlers; there's no obstacle there.
> Unfortunately, the typeHandler attribute in XML SQL mapping files just accepts TypeHandlerCallback
implementations as of iBATIS 2.0.8, throwing a nasty ClassCastException else.
> To make this more flexible, I suggest to load the specified class and check whether it
is a TypeHandler or TypeHandlerCallback implementation. This should be straightforward to
add to XmlSqlMapClientBuilder: just add a corresponding check to line 912/913.
>   Object typeHandler = Resources.classForName(callback).newInstance();
>   if (typeHandler instanceof TypeHandler) {
>     handler = (TypeHandler) handler;
>   }
>   else if (typeHandler instanceof TypeHandlerCallback) {
>     handler = new CustomTypeHandler((TypeHandlerCallback) typeHandlerCallback);
>   }
>   else {
>     throw SqlMapException("Invalid type handler class: ...");
>   }
> This should be pretty trivial to add and not cause any side effects, as far as I can
see. It would be great if you could get this into iBATIS 2.0.9 (or whatever your next planned
release is).
> Thanks in advance,
> Juergen

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