How to convert from a web::json::object to a map of strings

I have a json object, where one of the values is a python dictionary, that I'm sending to C++ as JSON.

I was trying to save the value as a std::map<string, string> which I thought would represent the data correctly.

There is a method in this, that can convert the Web JSON object into a json object json::object& web::json::value::as_object.

But there is no further method to convert that into a map of strings. Is the only option to iterate over every one of the values in the JSON object and make the map that way?