Question

我正在尝试在我的settings.yml文件中为我的静态文件的位置创建一个新字段（因此我可以从开发中的本地子目录更改为生产中的CDN），但我似乎无法获得基本的“你好世界”。这是我的Settings.hs：

data Extra = Extra
    { extraCopyright :: Text
    , extraAnalytics :: Maybe Text -- ^ Google Analytics
    , extraStatic :: Text
    } deriving Show

parseExtra :: DefaultEnv -> Object -> Parser Extra
parseExtra _ o = Extra
    <$> o .:  "copyright"
    <*> o .:? "analytics"
    <*> o .:  "static"

这是settings.yml的相关部分：

Default: &defaults
  host: "*4" # any IPv4 host
  port: 3000
  approot: "http://localhost:3000"
  copyright: Insert copyright statement here
  #analytics: UA-YOURCODE
  static: "/static"

最后，抛出错误的部分。我真的不知道如何在请求中包含它的值，所以我只是把代码放在每个请求上执行：

getHomeR :: Handler Html
getHomeR = do
    (formWidget, formEnctype) <- generateFormPost sampleForm
    let submission = Nothing :: Maybe (FileInfo, Text)
        handlerName = "getHomeR" :: Text
        test = fmap extraStatic getExtra
    defaultLayout $ do
        aDomId <- newIdent
        setTitle "Welcome To Yesod!"
        $(widgetFile "homepage")

我在postHomeR上添加了相同的行以及（test = fmap extraStatic getExtra）。我的小村庄：

<p>#{test}

最后，屏幕上出现错误：

Handler/Home.hs:37:11:
    No instance for (blaze-markup-0.5.1.5:Text.Blaze.ToMarkup
                       (HandlerT App IO Text))
      arising from a use of `toHtml'
    Possible fix:
      add an instance declaration for
      (blaze-markup-0.5.1.5:Text.Blaze.ToMarkup (HandlerT App IO Text))
    In the first argument of `Yesod.Core.Widget.asWidgetT
                              . toWidget', namely
       `toHtml test'
    In a stmt of a 'do' block:
      (Yesod.Core.Widget.asWidgetT . toWidget) (toHtml test)
    In a stmt of a 'do' block:
      do { (Yesod.Core.Widget.asWidgetT . toWidget)
             ((blaze-markup-0.5.1.5:Text.Blaze.Internal.preEscapedText
               . Data.Text.pack)
                "<h1>");
           ((Control.Monad.liftM (toHtml .) getMessageRender)
            >>=
               (\ urender_aaYh
                 -> (Yesod.Core.Widget.asWidgetT . toWidget)
                       (urender_aaYh MsgHello)));
          (Yesod.Core.Widget.asWidgetT . toWidget)
             ((blaze-markup-0.5.1.5:Text.Blaze.Internal.preEscapedText
               . Data.Text.pack)
                "</h1>\
                \<ol><li>Now that you have a working project you should use the <a href=\"http://www.yesodweb.com/book/\">Yesod book</a> to learn more. You can also use this scaffolded site to explore some basic concepts.</li><li> This page was generated by the ");
           (Yesod.Core.Widget.asWidgetT . toWidget) (toHtml handlerName);
           .... }
Build failure, pausing...

我有什么方法可以施展它吗？有没有什么办法可以让我在app启动时分配和加载变量，但是作为常量值可以在整个请求中访问？任何帮助将不胜感激!!

Answer 1

问题是：

let test = fmap extraStatic getExtra

getExtra是Handler行为，所以您想要的是：

test <- fmap extraStatic getExtra

Yesod自定义settings.yml字段类型不匹配

1 个答案: