Question

I have an HTML form like this one:

<form action="test" method="post">
  <input name="first_name" type="text"/>
  <input name="last_name" type="text" />
  <input name="age" type="text" />
  <input type="submit" value="Send"/>
</form>

How do I get the values of the input fields and print them on screen, just like in any other procedural programming language such as PHP, ASP or JSP?

I tried to solve the problem the following way:

:- use_module(library(http/thread_httpd)).
:- use_module(library(http/http_dispatch)).

:- http_handler(root(test), reply, []).
:- http_handler('test', reply, []).

server(Port) :-
        http_server(http_dispatch, [port(Port)]).

reply(Request) :-
        member(method(post), Request), !,
        http_read_data(Request, Data, []),
        format('application/x-www-form-urlencoded', []),
        format(Data).

That brought me nothing more than an error with the 500 code (internal server error).

Answer 1

I use library(http/http_parameters). With that, I can do

load_graph(Request) :-
    http_parameters(Request,
            [path(Path, [atom]),
             aperture(Aperture, [integer])]),

where load_graph is the handler for the form

...
html(form([action(Ref)],
      dl([dt('Root Path'), dd(input([name=path, type=text, value=Default])),
          dt('Aperture'), dd(select([name=aperture], Aplist)),
          dt('Go!'), dd(input([type=submit, value='Load!']))
      ]))).