Reviewing a PR just now, I'm reminded that the logic I half-recalled to
avoid empty serializations is only for strings. Would it be worth
changing [unit] serialization to avoid empty serializations there, too?
On 1/25/19 8:21 AM, Simon Van Casteren wrote:
It doesn't happen often of course, since you rarely use unit in a page
or RPC function. How I ran into it was actually via the now fixed bug
https://github.com/urweb/urweb/issues/117, I made some ADT's that got
around that bug by declaring all constructors to have at least one
parameter, unit if nothing else. That came back to bite me now...
A page with this signature:
val page: unit -> string -> transaction page
Would be affected by the issue I described. This obviously won't
happen much outside of you making a mistake (for example because first
the function took just a unit, then you added the string parameter),
but because it doesn't happen often and it's actually nginx making the
"mistake", I still thought it could help someone out in the future!
Simon
On Fri, 25 Jan 2019 at 13:57, Adam Chlipala <ad...@csail.mit.edu
<mailto:ad...@csail.mit.edu>> wrote:
Thanks for sharing that wisdom! Somehow I remember making a
special effort to encode empty strings with underscores, precisely
to avoid this problem (though it was appearing in Apache, if I
recall correctly). Can you point us to an example where it
arises, in a URL that an Ur/Web app generates itself?
On 1/25/19 5:13 AM, Simon Van Casteren wrote:
Hi,
I just ran into an awful problem combining urweb with nginx. By
default, nginx by default merges double slashes in urls, eg:
http://www.bla.com//users becomes http//www.bla.com/users
<http://www.bla.com/users>. This can be a problem for UrWeb
applications since a double slash is actually how urweb encodes
the unit or () value.
The solution is to use the option: "merge_slashes off".
It's not a bug in either application so I didnt want me make an
issue for it, but this could be useful info for other people
running Ur/Web programs behind nginx...
Simon
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