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Having persevered with mapping my existing database in grails, it actually made for much cleaner domain objects.

I never much liked when hibernate started creeping out of configuration and into the code via Java annotations, so on the same score, it was cathartic to remove the database aware gorm mappings from my domain classes.

Adding the hibernate configuration was straight forward and clean and tucked away in the conf/hibernate directory; an hibernate.cfg.xml file listing the mapping resources and an hbm.xml resource file for each entity.

All was going swimmingly until I was adding my last domain class; modelling an Application.

As soon as I wanted to “show” a particular Application I was getting a ClassCastException.

It would appear that I’m not the first to hit this, so luckily I didn’t have waste too much time trying to figure out why:

application/create throws java.lang.ClassCastException: Application cannot be cast to javax.servlet.ServletContext

Apparently…

there is a variable in the GSP binding called ‘application’ that is the ServletContext this gets overridden when you return the model from the controller

The bug is on create, but I guess as I am coming from the legacy database angle, I didn’t have to “create” before I tried to “show”.

Mmm.

Some time ago I looked at what was necessary to have Grails work on an existing database rather than the green field scenario painted in most examples.

It seemed straight forward enough, but beyond curiosity, I didn’t have anything I was particularly trying to achieve, so I moved along.

Yesterday, once again messing around with grails, I found something I couldn’t seem to achieve via gorm.

Basically, I couldn’t define the column mapping for an embedded class (where instead of mapping classes onto separate tables a class can be “embedded” within the current table).

I had hoped it would be a straight forward as defining the column mappings in the embedded class definition, but unfortunately not. Any mappings appear to be ignored.

I tried in the embedding class. No. I even experimented with the embedded property, but that was a long shot I didn’t expect to work anyway.

It would seem I will have to define the mapping in the old fashioned hibernate configuration file way.

One useful thing I did find in this frustrating experiment is that the configuration setting …
dataSource {
logSql = "true"
}

… provides a more readable format than …
hibernate {
show_sql = "true"
}


Not a total loss then!