Yesod: How to build parameterized routes

Question

I am try to pass a parameter to a route at runtime inside a hamlet template.

  buildFeedRow :: Item [Attribute Text] -> GWidget a a ()
  buildFeedRow item = do
    let f = unpackItem item
        u :: Text = url f
    [whamlet|
    <tr>
      <td>
        <a href="#{url f}">#{url f}
      <td>#{nextCrawlTime f}
      <td>#{crawlDelay f}
      <td>
         <a href="@{DeleteFeedR u}">Delete
      <td>Edit |]

It fails with a type error.

Couldn't match type `Route a' with `ConsoleRoute'
Expected type: ConsoleRoute -> [(Text, Text)] -> Text
Actual type: Route a -> [(Text, Text)] -> Text
Expected type: GHandler
                 a a (ConsoleRoute -> [(Text, Text)] -> Text)
  Actual type: GGHandler
                 a
                 a
                 (Data.Enumerator.Iteratee Data.ByteString.Internal.ByteString IO)
                 (Route a -> [(Text, Text)] -> Text)
In the first argument of `lift', namely `getUrlRenderParams'
In the first argument of `(>>=)', namely `lift getUrlRenderParams'

My question is how do you pass parameters to routes in a hamlet template.

Answer 1

I think the the type signature of your widget might be too generic. Since you're using a route, it now depends on your foundation type so it should have the type

buildFeedRow :: Item [Attribute Text] -> GWidget YourFoundation YourFoundation ()