How to mapping primary key is VARCHAR2 type and excute my method to generate it

I'm grails newbie.i want to mapping primary key with VARCHAR2 and generate primary key using my 开发者_Go百科method to generated its.how to solve this problem?

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In GORM you can specify your own function generating ids.

To specify column type take a look into documentation. For using VARCHAR2 in Oracle DB just set your property as String.