Question

I have a select element whose name is dotted (e.g. name = "select.first") and I have troubles getting its value with $_POST['select.first'].
Is it because of the dotted name? Is there a way of fixing this while keeping the dotted name?

Answer 1

From the HTML specs

ID and NAME tokens must begin with a letter ([A-Za-z]) and may be
followed by any number of letters, digits ([0-9]), hyphens ("-"),
underscores ("_"), colons (":"), and periods (".").

So it’s perfectly valid in HTML. PHP converts names with . to _ as detailed in the documentation.

Dots and spaces in variable names are converted to underscores. For example becomes $_REQUEST["a_b"].

This is the default behaviour, i’m not sure there’s a way around it except to either use underscore on both the server and client or to use . on the client and _ on the server.
I would use the former for consistency sake.