When you upload a file, you can do something like this in your controller:
def myAction = {
def file = request.get('csvfile')
file.transferTo(new File('/path/to/local/file'))
}
I do not understand the connection between your question and how the inputs in your form will be displayed on a domain object. If you do not want the contents of a file in your domain, you should not have a domain field defined for them.
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