Message Data transform other data type to SArray<char>,it can't support complicated data struct

I want to push a string as value to server,but can't work.
I notice that all data are transform to SArray,so it difficult to support comlicated data struct.
as said:
*A smart array that retains shared ownership. It provides similar
- functionalities comparing to std::vector, including data(), size(),
- operator[], resize(), clear(). SArray can be easily constructed from
- std::vector

but I can't do this:
std::vector vec;
SArray s(vec);

Start by tracing the server value transformation that converts data to SArray, then inspect SArray construction from std::vector. Reproduce the reported std::vector case and define done as successfully sending string or similarly structured values without the current conversion failure.

Written by the indexing model from the issue text.