posts: join powered by esqueleto

package.yaml

@@ -42,6 +42,7 @@ dependencies:
 - case-insensitive
 - wai
 - foreign-store
+- esqueleto
 
 # The library contains all of our application code. The executable
 # defined below is just a thin wrapper.

src/Handler/Posts.hs

@@ -8,7 +8,9 @@
 
 module Handler.Posts where
 
-import Import
+import           Import
+import qualified Database.Esqueleto      as E
+import           Database.Esqueleto      ((^.))
 
 postForm :: UserId -> Form Post
 postForm userId =
@@ -22,15 +24,37 @@ getPostsR :: Handler Html
 getPostsR = do
   userId <- fmap fst $ requireAuthPair
   (widget, enctype) <- generateFormPost $ postForm userId
-  allPosts :: [Entity Post] <- runDB $ selectList [] [ Desc PostId ]
+  allPosts <- runDB
+         $ E.select
+         $ E.from $ \(post `E.InnerJoin` user) -> do
+              E.on $ post ^. PostUserId E.==. user ^. UserId
+              E.orderBy [E.desc (post ^. PostId)]
+              return
+                  ( post ^. PostId
+                  , post ^. PostUserId
+                  , post ^. PostTitle
+                  , post ^. PostText
+                  , user ^. UserIdent
+                  )
   emptyLayout $ do
     $(widgetFile "posts")
 
 postPostsR :: Handler Html
 postPostsR = do
   userId <- fmap fst $ requireAuthPair
   ((result, widget), enctype) <- runFormPost $ postForm userId
-  allPosts :: [Entity Post] <- runDB $ selectList [] [ Desc PostId ]
+  allPosts <- runDB
+         $ E.select
+         $ E.from $ \(post `E.InnerJoin` user) -> do
+              E.on $ post ^. PostUserId E.==. user ^. UserId
+              E.orderBy [E.desc (post ^. PostId)]
+              return
+                  ( post ^. PostId
+                  , post ^. PostUserId
+                  , post ^. PostTitle
+                  , post ^. PostText
+                  , user ^. UserIdent
+                  )
   case result of
     FormSuccess post -> do
       _ <- runDB $ insert post

templates/posts.hamlet

@@ -9,12 +9,13 @@
     <button>Post
 
 <ul>
-  $forall post <- allPosts
+  $forall (E.Value postId, E.Value postUserId, E.Value title, E.Value text, E.Value author) <- allPosts
     <li>
-      <h2> #{postTitle $ entityVal post}
-      <p> #{postText $ entityVal post}
-      <form method=post action=@{PostR $ entityKey post}?_method=DELETE>
-        $if userId == (postUserId $ entityVal post)
+      <h2> #{title}
+      <p> #{text}
+      <p> #{author}
+      <form method=post action=@{PostR postId}?_method=DELETE>
+        $if userId == postUserId
           <button>Delete
         $else
           <p>