[Haskell-beginners] Yesod question - ajax.lhs

Fri May 20 02:38:41 CEST 2011

I'm using yesod 0.8.1

I'm playing around with yesod examples 0.8.0.1 and I noticed a few
things that send up some red flags

first thing, when I try to run ajax.lhs from the top level directory

src/ajax.lhs:6:3:
    Warning: In the use of `string'
             (imported from Yesod, but defined in Text.Blaze.Internal):
             Deprecated: "Use Blaze.Html.toHtml"

src/ajax.lhs:37:18:
    Warning: Deprecated syntax:
               quasiquotes no longer need a dollar sign: $parseRoutes

src/ajax.lhs:52:21:
    Warning: Deprecated syntax:
               quasiquotes no longer need a dollar sign: $hamlet

src/ajax.lhs:93:17:
    Warning: Deprecated syntax:
               quasiquotes no longer need a dollar sign: $hamlet

This is suggesting to me the example code hasn't caught up to the
changes in yesod, which can cause confusion for n00bs like me.

I'm trying to learn how to use jQuery via yesod, and when I see the
html generated from the current ajax.lhs this is what comes up

<!DOCTYPE html><html><head><title>Page 1</title><link rel="stylesheet"
href="/static/style%2Ecss?YaQxW21D"><script
src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js"></script><script
src="/static/script%2Ejs?NWBIzSLG"></script></head><body><ul
id="navbar"><li><a href="/page/page%2D1">Page 1</a></li><li><a
href="/page/page%2D2">Page 2</a></li><li><a href="/page/page%2D3">Page
3</a></li></ul><div id="content"><h1>Page 1</h1><article>My first
page</article></div></body></html>

I want to draw attention to
<script src="/static/script%2Ejs?NWBIzSLG"> and things like this. This
is the other red flag that the example code hasn't caught up to the
current state of Yesod. Am I interpreting the problem correctly?

Here is what the latest example of ajax.lhs looks like. Could someone
tell me what needs to change to prevent the above problems from
happening?

> {-# LANGUAGE TypeFamilies, QuasiQuotes, TemplateHaskell, MultiParamTypeClasses, OverloadedStrings #-}
> import Yesod
> import Yesod.Helpers.Static
> import Data.Monoid (mempty)

Like the blog example, we'll define some data first.

> data Page = Page
>   { pageName :: String
>   , pageSlug :: String
>   , pageContent :: String
>   }

> loadPages :: IO [Page]
> loadPages = return
>   [ Page "Page 1" "page-1" "My first page"
>   , Page "Page 2" "page-2" "My second page"
>   , Page "Page 3" "page-3" "My third page"
>   ]

> data Ajax = Ajax
>   { ajaxPages :: [Page]
>   , ajaxStatic :: Static
>   }
> type Handler = GHandler Ajax Ajax

> staticFiles "static/yesod/ajax"

> mkYesod "Ajax" [$parseRoutes|
> /                  HomeR   GET
> /page/#String      PageR   GET
> /static            StaticR Static ajaxStatic
> |]

> instance Yesod Ajax where
>   approot _ = ""
>   defaultLayout widget = do
>   Ajax pages _ <- getYesod
>   content <- widgetToPageContent widget
>   hamletToRepHtml [$hamlet|
> \<!DOCTYPE html>
>
> <html>
>   <head>
>     <title>#{pageTitle content}
>     <link rel="stylesheet" href="@{StaticR style_css}">
>     <script src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js">
>     <script src="@{StaticR script_js}">
>     \^{pageHead content}
>   <body>
>     <ul id="navbar">
>       $forall page <- pages
>         <li>
>           <a href="@{PageR (pageSlug page)}">#{pageName page}
>     <div id="content">
>       \^{pageBody content}
> |]

> getHomeR :: Handler ()
> getHomeR = do
>   Ajax pages _ <- getYesod
>   let first = head pages
>   redirect RedirectTemporary $ PageR $ pageSlug first

> getPageR :: String -> Handler RepHtmlJson
> getPageR slug = do
>   Ajax pages _ <- getYesod
>   case filter (\e -> pageSlug e == slug) pages of
>       [] -> notFound
>       page:_ -> defaultLayoutJson (do
>           setTitle $ string $ pageName page
>           addHamlet $ html page
>           ) (json page)
>  where
>   html page = [$hamlet|
> <h1>#{pageName page}
> <article>#{pageContent page}
> |]
>   json page = jsonMap
>       [ ("name", jsonScalar $ pageName page)
>       , ("content", jsonScalar $ pageContent page)
>       ]

> main :: IO ()
> main = do
>   pages <- loadPages
>   let s = static "static/yesod/ajax"
>   warpDebug 3000 $ Ajax pages s