// cacheKeys will append to oldKeys, and also return as newKeys, all cache keys this finder may use to find the provided model.
// the reason there may be multiple keys is that we don't know which ancestor will be used when finding the model.
func (self finder) cacheKeys(c PersistenceContext, model interface{}, oldKeys *[]string) (newKeys []string, err error) {
var id key.Key
if _, id, err = getTypeAndId(model); err != nil {
return
}
values := make([]interface{}, len(self.fields))
val := reflect.ValueOf(model).Elem()
for index, field := range self.fields {
values[index] = val.FieldByName(field.Name).Interface()
}
if oldKeys == nil {
oldKeys = &[]string{}
}
for id != "" {
*oldKeys = append(*oldKeys, self.keyForValues(id.Parent(), values))
id = id.Parent()
}
newKeys = *oldKeys
return
}
