[api] fix a bug when the size is None
[api] fix a bug when the size is None

Chilledheart/seahub,madflow/seahub,miurahr/seahub,miurahr/seahub,cloudcopy/seahub,cloudcopy/seahub,miurahr/seahub,Chilledheart/seahub,Chilledheart/seahub,madflow/seahub,madflow/seahub,cloudcopy/seahub,cloudcopy/seahub,madflow/seahub,Chilledheart/seahub,miurahr/seahub,Chilledheart/seahub,madflow/seahub