(Quick Reference)
                uploadForm
Purpose
Creates a form that can submit multi-part data for file uploads.
Examples
<g:uploadForm name="myUpload">
    <input type="file" name="myFile" />
</g:uploadForm>Description
Identical to the standard 
form tag except that it sets the 
enctype attribute to 
"multipart/form-data" automatically.
Attributes
- action(optional) - the name of the action to use in the link; if not specified the default action will be linked
- controller(optional) - the name of the controller to use in the link; if not specified the current controller will be linked
- id(optional) - The id to use in the link
- url(optional) - A map containing the action, controller, id etc.
Source