yesod

I have a Yesod form for editing the contents of some static pages which are written using markdown (processed using Pandoc). I want to have two buttons - a 'preview' button which processes the markup and displays the result underneath the form, and a 'submit' button which saves the contents to the database. What is the simplest way to do this with Yesod? All the form examples in the Yesod book have exactly one button. I've looked at the exposed functions / api, but I even if I add more than one submit button with different names and/or values to the form I can't figure out how to get Yesod to

I'm running "cabal install && yesod devel" using yesod 0.9.2.2 but it is only listening using ipv6. Does anyone know how to configure it to listen on ipv4 as well? I'm running it on Windows 7. Thanks The symptom you describe have so far been observed on BSD and Debian, but it looks like Windows is also affected. It is a known problem with Yesod, or actually with Wasp, or, to be precise, with the network library. One place to follow up on this issue is this githup issue or the current discussion on haskell-lists , which was partly caused by your question. While I don't currently have a similar

I'm playing with scaffolded site and i want to send user to the registration page after he logged in for the first time with OpenID or Google Account. I've came up with this: getAuthId creds = runDB $ do x ← getBy $ UniqueUser $ credsIdent creds case x of Just (Entity uid _) → return $ Just uid Nothing → do return $ Just $ Key (PersistInt64 0) And in HomeR handler i check for UserId value, showing registration form in case of zero. This approach works, but seems hackish. What is the proper way to deal with such problem? I would recommend splitting the information up into two entities: a User

I'd like to url-encode some Text (e.g., replace each space with a %20, etc.). I found "HTTP" Network.HTTP.Base.urlEncode and could use that, but I'm wondering if there's something else that's normally used in the Yesod ecosystem. Michael Snoyman Unfortunately, due to the complexity of URL escaping, the real answer is "it depends." There are slightly different rules for the percent encoding of path segments and query strings, for example. I don't know exactly what you're trying to encode, but I'd recommend sticking to the http-types package. One place to start would be urlEncode , though there

It seems impossible to use Yesod together with the Darcs library due to a linker problem. I tracked down the problem and need hints to work around it by people familiar with Darcs internals. When using the darcs library in a Yesod application, I get the following error: GHCi runtime linker: fatal error: I found a duplicate definition for symbol sha256_init whilst processing object file /home/sebfisch/.cabal/lib/darcs-2.9.5/ghc-7.4.2/libHSdarcs-2.9.5.a This could be caused by: * Loading two different object files which export the same symbol * Specifying the same object file twice on the GHCi

I would like to create a website using Yesod and websockets (html5). Can I use websockets with Yesod webframework? Yes, as Thomas M. DuBuisson pointed out in the comments: a WebSocket handler is implemented in WAI which is the interface Yesod is using to communicate with it's backends. I can't comment on how well it works in it's current form, but you can download and try it from Hackage . 来源： https://stackoverflow.com/questions/10963175/websockets-in-yesod

I am trying to use Database.Persistant to make a database for a Scotty app, and I cannot figure out the syntax for adding a foreign key constraint between tables. For example, I have a User table and a Post table, and I want the Post table to have an attribute authorId which references UserId in User . This can be accomplished quite easily in raw SQL, but I want to be able to access the data through haskell without resorting to raw sql commands. Also, the constraints would be overwritting upon database migrations. This is what I have at the moment to define the database: share [mkPersist