Mine

		public ProductForm(String arg0, IModel arg1) {
			super(arg0, arg1);
			setMultiPart(true);
			add(new RequiredTextField("model"));
			add(new RequiredTextField("description"));
			final CategoryDao cdao = (CategoryDao)getCtx().getBean("categoryDao");
			add(new DropDownChoice("category.name",new LoadableDetachableModel() {
				private static final long serialVersionUID = 1L;
				@Override
				protected Object load() {
					return cdao.all();
				}
			}));
			add(new RequiredTextField("price").setType(BigDecimal.class));
			add(u = new FileUploadField("image"));
			add(new TextArea("body").setRequired(true));
		}