how do I create a file upload in grails which works with oracle?
If you want to use a Blob field in Oracle then set your domain property to byte[] and set the type to org.hibernate.type.MaterializedBlobType. The MaterializedBlobType handles conversion back and forth between Oracle (presumably other databases, but I've only done this on Oracle) and byte[].
byte[] blobFilestatic mapping = { blobFile type: org.hibernate.type.MaterializedBlobType}