// WriteKey encodes a key to the buffer. If context is WithContext, then this
// encoded value will include the appid and namespace of the key.
func WriteKey(buf Buffer, context KeyContext, k *ds.Key) (err error) {
// [appid ++ namespace]? ++ [1 ++ token]* ++ NULL
defer recoverTo(&err)
appid, namespace, toks := k.Split()
if context == WithContext {
panicIf(buf.WriteByte(1))
_, e := cmpbin.WriteString(buf, appid)
panicIf(e)
_, e = cmpbin.WriteString(buf, namespace)
panicIf(e)
} else {
panicIf(buf.WriteByte(0))
}
for _, tok := range toks {
panicIf(buf.WriteByte(1))
panicIf(WriteKeyTok(buf, tok))
}
return buf.WriteByte(0)
}
// dsF2R (DS fake-to-real) converts a DSKey back to an SDK *Key.
func dsF2R(aeCtx context.Context, k *ds.Key) (*datastore.Key, error) {
if k == nil {
return nil, nil
}
// drop aid.
_, ns, toks := k.Split()
err := error(nil)
aeCtx, err = appengine.Namespace(aeCtx, ns)
if err != nil {
return nil, err
}
ret := datastore.NewKey(aeCtx, toks[0].Kind, toks[0].StringID, toks[0].IntID, nil)
for _, t := range toks[1:] {
ret = datastore.NewKey(aeCtx, t.Kind, t.StringID, t.IntID, ret)
}
return ret, nil
}