Add part4

part4/src/Data/Article/Comment.elm

@@ -0,0 +1,48 @@
+module Data.Article.Comment exposing (Comment, CommentId, commentIdDecoder, decoder, idToString)
+
+import Data.Article.Author as Author exposing (Author)
+import Date exposing (Date)
+import Json.Decode as Decode exposing (Decoder)
+import Json.Decode.Extra
+import Json.Decode.Pipeline exposing (custom, decode, required)
+
+
+type alias Comment =
+    { id : CommentId
+    , body : String
+    , createdAt : Date
+    , updatedAt : Date
+    , author : Author
+    }
+
+
+
+-- SERIALIZATION --
+
+
+decoder : Decoder Comment
+decoder =
+    decode Comment
+        |> required "id" commentIdDecoder
+        |> required "body" Decode.string
+        |> required "createdAt" Json.Decode.Extra.date
+        |> required "updatedAt" Json.Decode.Extra.date
+        |> required "author" Author.decoder
+
+
+
+-- IDENTIFIERS --
+
+
+type CommentId
+    = CommentId Int
+
+
+idToString : CommentId -> String
+idToString (CommentId id) =
+    toString id
+
+
+commentIdDecoder : Decoder CommentId
+commentIdDecoder =
+    Decode.map CommentId Decode.int