Getting old Value from Prepare interceptor

Hi, I'm using a prpareInterceptor,to save the newatt value and get the oldattr value and save it into another filed.The problem that the interceptor save in the two fields the value of the newattr.

if (ctx.getModelService().isModified(voyageModel)) { if (ctx.isModified(vModel, VModel.NEWATTR)) { final VModel oldVModel = modelService.get(vModel.getPk()); vModel.setOldAttr(oldVModel.getNewAttr()); }

}