// getTypeAndId will validate that the model is a pointer to a struct, and that it has a key.Key field name Id.
func getTypeAndId(model interface{}) (typ reflect.Type, id key.Key, err error) {
val := reflect.ValueOf(model)
if val.Kind() != reflect.Ptr {
err = errors.Errorf("%+v is not a pointer", model)
return
}
if val.Elem().Kind() != reflect.Struct {
err = errors.Errorf("%+v is not a pointer to a struct", model)
return
}
typ = val.Elem().Type()
idField, found := val.Elem().Type().FieldByName(idFieldName)
if !found {
err = errors.Errorf("%+v does not have a field named Id", model)
return
}
if !idField.Type.AssignableTo(reflect.TypeOf(key.Key(""))) {
err = errors.Errorf("%+v has an Id field of type %v, that isn't assignable to key.Key", model, idField.Type)
return
}
if idField.Tag.Get("datastore") != "-" {
err = errors.Errorf("%+v has an Id field stored in datastore, which will cause no end of trouble. Set the tag of the Id field to be `datastore:\"-\"`", model)
return
}
id = val.Elem().FieldByName(idFieldName).Interface().(key.Key)
if id.Kind() != typ.Name() && id.Kind() != typ.Name()+"Log" {
err = errors.Errorf("You can only read and write types with keys with the type name, or type name + 'Log'. You tried to read or write a %v with key %v", typ, id)
return
}
return
}
func ToGAE(c appengine.Context, k key.Key) *datastore.Key {
if len(k) < 1 {
return nil
}
kind, stringID, intID, parent := k.Split()
return datastore.NewKey(c, kind, stringID, intID, ToGAE(c, key.Key(parent)))
}
func FromGAEWithoutValidate(k *datastore.Key) (result key.Key) {
if k == nil {
return key.Key("")
}
result = key.NewWithoutValidate(k.Kind(), k.StringID(), k.IntID(), FromGAEWithoutValidate(k.Parent()))
return
}
func FromGAE(k *datastore.Key) (result key.Key, err error) {
if k == nil {
return key.Key(""), nil
}
parent, err := FromGAE(k.Parent())
if err != nil {
return
}
return key.New(k.Kind(), k.StringID(), k.IntID(), parent)
}