[web-devel] [Yesod] Re: Yesod: Dynamic subdomains

[Michael Snoyman]

I think that the better approach to this is something along the lines
of CleanPath[1] (which is horribly documented btw). Instead of just
having some arbitrary Map in the Request value, we explicitly pass
extra data to the Application.

[1] http://hackage.haskell.org/packages/archive/wai-extra/0.4.1.2/doc/html/Network-Wai-Middleware-CleanPath.html

On Sat, Aug 27, 2011 at 11:14 PM, Greg Weber <greg at gregweber.info> wrote:
> I agree that WAI is well optimized for the common use case, and that this
> particular use case may call for a change in Yesod rather than WAI. However,
> not being able to store arbitrary data does limit what can be achieved in
> WAI.
> In Ruby there things (like authentication) that are being done in Rack that
> would be difficult to achieve in an extensible way without that capability.
> WAI may not seem like the correct layer for those kinds of features.
> However, in an environment like Ruby where there *every* web framework uses
> Rack, there is a lot of advantage that can be gained by pushing core
> features down there.
> On Sat, Aug 27, 2011 at 12:10 PM, Michael Snoyman <michael at snoyman.com>
> wrote:
>>
>> The stylesheet: Pandoc compiled without -fhighlighting (as we both
>> knew would happen eventually ;)). I'm recompiling and uploading a new
>> copy now.
>>
>> I don't really think this has anything to do with WAI. Firstly, I was
>> mistaken in using the Host request header, WAI already provides a
>> serverName record in the Request datatype, I'd simply forgotten about
>> it. The routing issue is that Yesod only pays attention to the path
>> info for routing, so we're "hacking" WAI to expose extra information
>> in that record that wouldn't normally be there. I think the real
>> question is if Yesod needs to be modified to allow routing on
>> something else, but I think that:
>>
>> 1. We've optimized for the common case, and any deviation from what
>> we've done will make normal usage of Yesod much more difficult.
>> 2. Even though this is a hack, it's not a particularly bad one, and
>> all normal Yesod features like type-safe URLs and declarative routing
>> still work without a hitch.
>>
>> Michael
>>
>> On Sat, Aug 27, 2011 at 9:56 PM, Greg Weber <greg at gregweber.info> wrote:
>> > Great example! Inspired me to post a recipe for re-directing from www to
>> > the
>> > main domain: http://www.yesodweb.com/show/topic/536
>> > Did the syntax high-lighting stylesheet disappear?
>> >
>> > The domain-based routing does make me wonder though- in Rack the data
>> > structure is a hash instead of a record and I could place the sub-domain
>> > somewhere in the hash. Having a reliable record is much nicer than a
>> > hash.
>> > However, this shows a use-case where we want to save off extra data at
>> > the
>> > WAI level, but there is no way to do so. It seems like WAI should be
>> > modified in some way to properly accommodate this use case. The first
>> > thing
>> > that comes to my mind is having an extra parameter in the request record
>> > that is a Map expressly for the purpose of storing data for later use.
>> > What
>> > do you think?
>> > Greg Weber
>> >
>> > On Sat, Aug 27, 2011 at 11:09 AM, Michael Snoyman <michael at snoyman.com>
>> > wrote:
>> >>
>> >> On Fri, Aug 26, 2011 at 4:09 PM, "Timo B. Hübel" <t.h at gmx.info> wrote:
>> >> > Hi,
>> >> >
>> >> > I am building a Yesod web app which should support dynamic
>> >> > subdomains.
>> >> > I.e. a user registers as "foobar" on http://www.example.com and can
>> >> > afterwards access her content via http://foobar.example.com
>> >> >
>> >> > Is this possible at all? I am wondering, because the server name is
>> >> > somehow hard coded in Settings.hs as approot.
>> >> >
>> >> > If it is possible: How do I access the domain name in a handler
>> >> > function?
>> >> >
>> >> > Thanks!
>> >> > Timo
>> >>
>> >> Hi Timo,
>> >>
>> >> I've put up a cookbook recipe for domain-based routing[1]. It doesn't
>> >> require checking domain names in the handler function at all, but
>> >> instead uses the normal routing mechanism in Yesod. As a direct answer
>> >> to your question, to get access to the domain name, you'll want to get
>> >> the WAI request value via waiRequest[2] and then lookup the "Host"
>> >> header in requestHeaders[3].
>> >>
>> >> Let's direct any follow-up discussion to the Yesod mailing list (CCed).
>> >>
>> >> Michael
>> >>
>> >> [1] http://www.yesodweb.com/wiki/Domain-based%20routing
>> >> [2]
>> >>
>> >> http://hackage.haskell.org/packages/archive/yesod-core/0.8.3.2/doc/html/Yesod-Handler.html#v:waiRequest
>> >> [3]
>> >>
>> >> http://hackage.haskell.org/packages/archive/wai/0.4.1/doc/html/Network-Wai.html#v:requestHeaders
>> >
>> >
>
>