[hibernate-issues] [Hibernate-JIRA] Commented: (HHH-2569) Improve cast() HQL function to support user defined function calls

[Max Rydahl Andersen (JIRA)]

    [ http://opensource.atlassian.com/projects/hibernate/browse/HHH-2569?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_26728 ] 

Max Rydahl Andersen commented on HHH-2569:
------------------------------------------

note: you don't need a new dialect for custom functions in H3.2.

Use cfg.addSqlFunction(x,y)



> Improve cast() HQL function to support user defined function calls
> ------------------------------------------------------------------
>
>                 Key: HHH-2569
>                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-2569
>             Project: Hibernate3
>          Issue Type: Improvement
>          Components: query-hql
>    Affects Versions: 3.2.3
>         Environment: Hibernate 3.2.3ga
> DB2 UDB 8.1-9.0
>            Reporter: Gergely Papp
>         Attachments: CastFunction.java
>
>
> The cast() function could enable the HQL language to call user defined functions that are not explicitly defined in the dialect. 
> This is quite easy, considering everything is ready for it in the Hibernate framework, except for the problems in the actual SQL rendering of the function. 
> Currently the org.hibernate.dialect.function.CastFunction's render() method receives the arguments as a list, where the last argument is always the target type of the cast. For functions undefined in the dialect the arguments are split at commas.
> eg. cast (func(a,b) as int) is received as ["func(a", "b)", "int"]
> The problem here is that the arguments are checked if their size equals to two. This is the case for pre-defined functions, but not for user functions that have more than 1 parameters. (NB. currently this allows you to call user-defined functions with a single parameter and only fails on multi parameter functions, which could classify this as a bug)
> However if the method is modified, to accept arguments lists with more than 2 elements, and we concatenate the arguments before it, this issue could be solved.
> This would enhance the HQL a lot, as using user defined functions in several projects is a must, but writing a new dialect for it is not something an average programmer can figure out.
> The proposed modification is attached, it has been tested with DB2 and seems to work as expected, I hope it can find it's way  in the release soon as our project depends on this. 
> (The best would be to connect to the db and query the user-defined functions from it on startup, and register those in the dialect, but I think that's quite a huge modification.) 

-- 
This message is automatically generated by JIRA.
-
If you think it was sent incorrectly contact one of the administrators: http://opensource.atlassian.com/projects/hibernate/secure/Administrators.jspa
-
For more information on JIRA, see: http://www.atlassian.com/software/jira