[Erlangweb-users] Primitive types, duplicate values and wpart_valid

[Roberto A. <rob...@er...>]

Hi all,

I have a user-defined primitive type who relies on double entries in the POST list during validation. The type is more or less in the same situation as the wtype_password, which is expected to receive one or two POST variables with the same name (for confirmation purposes).

If this was working in Erlang Web 1.3, it doesn't work with Erlang Web 1.4 anymore. This is due to the wpart_valid:zip_get/4 function,  which removes every duplicate entry, making exceptions for the password and collection types.

-spec(zip_get/4 :: (list(tuple()), list(string()), 
		    list(tuple()), list(tuple())) -> list(tuple())).
zip_get([],[],_,Acc)->
    lists:reverse(Acc);
zip_get([{collection, _}|T1],[H2|T2], POST, Acc) ->
    In = proplists:get_all_values(H2,POST),
    zip_get(T1,T2,POST,[In|Acc]);
zip_get([{password, _}|T1], [H2|T2], POST, Acc) ->
    case proplists:get_all_values(H2, POST) of
	[_, _] = Val ->
	    zip_get(T1, T2, POST, [Val|Acc]);
	[Val] ->
	    zip_get(T1, T2, POST, [Val|Acc]);
	_ ->
	    zip_get(T1, T2, POST, [undefined|Acc])
    end;
zip_get([_|T1],[H2|T2], POST, Acc) ->
    In = proplists:get_value(H2,POST),
    zip_get(T1,T2,POST,[In|Acc]).

Notice the get_value in the last clause, as opposite to get_all_values, which I think it was the default behaviour of earlier versions of Erlang Web. It can't simply replaced into a get_all_values since that will break all others data types (such as wtype_time) which rely on exactly one element for validation.

Is there any reason why this behaviour was changed?

Cheers,

Roberto Aloi
-- 
University of Kent - Erlang Solutions Ltd.
Blog: http://aloiroberto.wordpress.com
Twitter: @prof3ta