// Get loads the entity stored for k into dst, which may be either a struct
// pointer or a Map. If there is no such entity for the key, Get returns
// ErrNoSuchEntity.
//
// The values of dst's unmatched struct fields or Map entries are not modified.
// In particular, it is recommended to pass either a pointer to a zero valued
// struct or an empty Map on each Get call.
//
// ErrFieldMismatch is returned when a field is to be loaded into a different
// type than the one it was stored from, or when a field is missing or
// unexported in the destination struct. ErrFieldMismatch is only returned if
// dst is a struct pointer.
func Get(c appengine.Context, k *Key, dst interface{}) os.Error {
if !k.valid() {
return ErrInvalidKey
}
req := &pb.GetRequest{
Key: []*pb.Reference{
keyToProto(c.AppID(), k),
},
}
res := &pb.GetResponse{}
err := c.Call("datastore_v3", "Get", req, res)
if err != nil {
return err
}
if len(res.Entity) == 0 || res.Entity[0].Entity == nil {
return ErrNoSuchEntity
}
if m, ok := dst.(Map); ok {
return loadMap(m, k, res.Entity[0].Entity)
}
sv, err := asStructValue(dst)
if err != nil {
return err
}
return loadStruct(sv, k, res.Entity[0].Entity)
}
// Delete deletes the entity for the given key.
func Delete(c appengine.Context, k *Key) os.Error {
if !k.valid() {
return ErrInvalidKey
}
req := &pb.DeleteRequest{
Key: []*pb.Reference{
keyToProto(c.AppID(), k),
},
}
res := &pb.DeleteResponse{}
return c.Call("datastore_v3", "Delete", req, res)
}
// Put saves the entity src into the datastore with key k. src may be either a
// struct pointer or a Map; if the former then any unexported fields of that
// struct will be skipped.
// If k is an incomplete key, the returned key will be a unique key
// generated by the datastore.
func Put(c appengine.Context, k *Key, src interface{}) (*Key, os.Error) {
if !k.valid() {
return nil, ErrInvalidKey
}
var e *pb.EntityProto
if m, ok := src.(Map); ok {
var err os.Error
e, err = saveMap(c.AppID(), k, m)
if err != nil {
return nil, err
}
} else {
sv, err := asStructValue(src)
if err != nil {
return nil, err
}
e, err = saveStruct(c.AppID(), k, sv)
if err != nil {
return nil, err
}
}
req := &pb.PutRequest{
Entity: []*pb.EntityProto{e},
}
res := &pb.PutResponse{}
err := c.Call("datastore_v3", "Put", req, res)
if err != nil {
return nil, err
}
if len(res.Key) == 0 {
return nil, os.NewError("datastore: internal error: server did not return a key")
}
key, err := protoToKey(res.Key[0])
if err != nil || key.Incomplete() {
return nil, os.NewError("datastore: internal error: server returned an invalid key")
}
return key, nil
}
// fullAppID returns the full AppID for c.
func fullAppID(c appengine.Context) string {
if c, ok := c.(fullAppIDer); ok {
return c.FullAppID()
}
return c.AppID()
}