Update advanced/part4

advanced/part4/src/PaginatedList.elm

@@ -1,8 +1,11 @@
-module PaginatedList exposing (PaginatedList, fromList, map, mapPage, page, total, values, view)
+module PaginatedList exposing (PaginatedList, fromList, fromRequestBuilder, map, page, total, values, view)
 
 import Html exposing (Html, a, li, text, ul)
 import Html.Attributes exposing (class, classList, href)
 import Html.Events exposing (onClick)
+import Http
+import HttpBuilder exposing (RequestBuilder)
+import Task exposing (Task)
 
 
 
@@ -54,29 +57,18 @@ map transform (PaginatedList info) =
     PaginatedList { info | values = List.map transform info.values }
 
 
-mapPage : (Int -> Int) -> PaginatedList a -> PaginatedList a
-mapPage transform (PaginatedList info) =
-    PaginatedList { info | page = transform info.page }
-
-
 
 -- VIEW
 
 
-view : (Int -> msg) -> PaginatedList a -> Int -> Html msg
-view toMsg list resultsPerPage =
+view : (Int -> msg) -> PaginatedList a -> Html msg
+view toMsg (PaginatedList info) =
     let
-        totalPages =
-            ceiling (toFloat (total list) / toFloat resultsPerPage)
-
-        activePage =
-            page list
-
         viewPageLink currentPage =
-            pageLink toMsg currentPage (currentPage == activePage)
+            pageLink toMsg currentPage (currentPage == info.page)
     in
-    if totalPages > 1 then
-        List.range 1 totalPages
+    if info.total > 1 then
+        List.range 1 info.total
             |> List.map viewPageLink
             |> ul [ class "pagination" ]
 
@@ -96,3 +88,31 @@ pageLink toMsg targetPage isActive =
             ]
             [ text (String.fromInt targetPage) ]
         ]
+
+
+
+-- HTTP
+
+
+{-| I considered accepting a record here so I don't mess up the argument order.
+-}
+fromRequestBuilder :
+    Int
+    -> Int
+    -> RequestBuilder (PaginatedList a)
+    -> Task Http.Error (PaginatedList a)
+fromRequestBuilder resultsPerPage pageNumber builder =
+    let
+        offset =
+            (pageNumber - 1) * resultsPerPage
+
+        params =
+            [ ( "limit", String.fromInt resultsPerPage )
+            , ( "offset", String.fromInt offset )
+            ]
+    in
+    builder
+        |> HttpBuilder.withQueryParams params
+        |> HttpBuilder.toRequest
+        |> Http.toTask
+        |> Task.map (\(PaginatedList info) -> PaginatedList { info | page = pageNumber })