Store custom data types into session

[StefanoPetrilli]

As far as I understand from the error message the types that it's possible to store at the moment inside crow::SessionMiddleware<crow::InMemoryStore>::context are long int, bool, string and double.

Would it be possible to expand the allowed data types to allow also other data types and ideally also custom data types?

Ideally what I would like to do would be:

  custom_data_type item = {...};
  session.set(itemName, item);

Based on my limited knowledge of C++ I have not fully understood why at the moment it is limited to that set of data types and where in the codebase this limitation is imposed.

[MichaelSB]

This restriction seems to have its origin in crow::session::multi_value, which is a (wrapped) variant using C++-17 or a struct using crow::json::wvalue instead when C++-11/14 is used. I don't see how this could be expanded to allow custom types. At least not easily. I'd probably convert my objects to json and store the dump as strings. This does not work for all types of custom data of course.

[dranikpg]

Based on my limited knowledge of C++ I have not fully understood why at the moment it is limited to that set of data types and where in the codebase this limitation is imposed.

Originally, because we also have a FileStore that will store all the data in the filesystem and it's not clear on how to convert it easily (without providing lot's of serialization stuff or json). We could however make it possible to store crow::json values in both and something like std::any for the in memory store