Customizing behaviour on incorrect type in JSON

[omartijn]

I'd like to be able to customize what happens when deserializing a value that is defined in the JSON, but that has the wrong type. As an example, the following JSON:

{"x":"abc"}

and deserializing like this:

struct X {
    int x;

    template <typename io_type>
    void json_io(io_type& io)
    {
        json_dto::optional("x", x, 0);
    }
};

This leads to an exception because we are expecting a number, but are getting a string instead. It'd be nice if we could set a policy that we use the default value in that case.

[omartijn]

Thinking about this a bit, we'd probably have to ensure that we have the Reader_Writer parameter for all (read|write)_json_value functions. It's now there for some (i.e. std::optional and std::vector) but not for others (i.e. std::string).

Then we can define a member function to invoke if the type is incorrect, which in the default implementation would throw. Do you think that makes sense?

[eao197]

Hi!

My first thought is to use a special Reader_Writer implementation that checks the type of a value in rapidjson::Value and then reads it or uses a default value.