HTTP IN value checking

I have a working httpin port, where i send the data “{ “y”: xxxx }” where xxxx = 4 digits.
I then can do value.y and get those digits.
Is it possible, for both type checking and security reasons, check what variables it contains, to avoid system failure?
when i try to do system.log(value), i get the pointer’s address, and when i do log(value.y) i see the value.
but how can i see the complete table, or atleast have a prior check that value.y exists?
I wish to make it a bit more secure, as not only having an input value “y”, but also some kind of password, or any other kind of verification, to make it more private

if (“y” in value) { … }


thanks Peter