Fix pagination not working correctly with multiple feeds

lib/frenzy_web/controllers/feed_controller.ex

@@ -38,9 +38,30 @@ defmodule FrenzyWeb.FeedController do
         DateTime.compare(a, b) == :gt
       end)
 
+    first_item = List.first(items)
+    last_item = List.last(items)
+
+    prev_page_path =
+      if !is_nil(first_item) &&
+           Repo.exists?(from i in Item, where: i.date > ^first_item.date and i.feed_id == ^id) do
+        current_path(conn, %{after: first_item.id})
+      else
+        nil
+      end
+
+    next_page_path =
+      if !is_nil(last_item) &&
+           Repo.exists?(from i in Item, where: i.date < ^last_item.date and i.feed_id == ^id) do
+        current_path(conn, %{before: last_item.id})
+      else
+        nil
+      end
+
     render(conn, "show.html", %{
       feed: feed,
-      items: items
+      items: items,
+      next_page_path: next_page_path,
+      prev_page_path: prev_page_path
     })
   end
 

lib/frenzy_web/controllers/group_controller.ex

@@ -112,9 +112,34 @@ defmodule FrenzyWeb.GroupController do
         DateTime.compare(a, b) == :gt
       end)
 
+    first_item = List.first(items)
+    last_item = List.last(items)
+
+    prev_page_path =
+      if !is_nil(first_item) &&
+           Repo.exists?(
+             from i in Item, where: i.date > ^first_item.date and i.feed_id in ^feed_ids
+           ) do
+        current_path(conn, %{after: first_item.id})
+      else
+        nil
+      end
+
+    next_page_path =
+      if !is_nil(last_item) &&
+           Repo.exists?(
+             from i in Item, where: i.date < ^last_item.date and i.feed_id in ^feed_ids
+           ) do
+        current_path(conn, %{before: last_item.id})
+      else
+        nil
+      end
+
     render(conn, "read.html", %{
       group: group,
-      items: items
+      items: items,
+      prev_page_path: prev_page_path,
+      next_page_path: next_page_path
     })
   end
 end

lib/frenzy_web/templates/feed/show.html.eex

@@ -17,9 +17,9 @@
 
 <h3 class="mt-4">Items</h3>
 
-<%= unless is_nil(prev_page_path(@conn, @items)) do %>
+<%= unless is_nil(@prev_page_path) do %>
   <p class="text-center">
-    <a href="<%= prev_page_path(@conn, @items) %>" class="pagination-link">Newer</a>
+    <a href="<%= @prev_page_path %>" class="pagination-link">Newer</a>
   </p>
 <% end %>
 
@@ -41,8 +41,8 @@
   </tbody>
 </table>
 
-<%= unless is_nil(next_page_path(@conn, @items)) do %>
+<%= unless is_nil(@next_page_path) do %>
   <p class="text-center">
-    <a href="<%= next_page_path(@conn, @items) %>" class="pagination-link">Older</a>
+    <a href="<%= @next_page_path %>" class="pagination-link">Older</a>
   </p>
 <% end %>

lib/frenzy_web/templates/group/read.html.eex

@@ -1,8 +1,8 @@
 <h1><%= @group.title %></h1>
 
-<%= unless is_nil(prev_page_path(@conn, @items)) do %>
+<%= unless is_nil(@prev_page_path) do %>
   <p class="text-center">
-    <a href="<%= prev_page_path(@conn, @items) %>" class="pagination-link">Newer</a>
+    <a href="<%= @prev_page_path %>" class="pagination-link">Newer</a>
   </p>
 <% end %>
 
@@ -34,8 +34,8 @@
   </tbody>
 </table>
 
-<%= unless is_nil(next_page_path(@conn, @items)) do %>
+<%= unless is_nil(@next_page_path) do %>
   <p class="text-center">
-    <a href="<%= next_page_path(@conn, @items) %>" class="pagination-link">Older</a>
+    <a href="<%= @next_page_path %>" class="pagination-link">Older</a>
   </p>
 <% end %>

lib/frenzy_web/views/feed_view.ex

@@ -1,32 +1,3 @@
 defmodule FrenzyWeb.FeedView do
   use FrenzyWeb, :view
-  alias Frenzy.{Repo, Item}
-  import Ecto.Query
-
-  @spec next_page_path(Plug.Conn.t(), [Frenzy.Item.t()]) :: String.t() | nil
-  def next_page_path(_conn, []), do: nil
-
-  def next_page_path(conn, items) do
-    %Item{id: id, date: date} = List.last(items)
-    has_older = Repo.exists?(from i in Item, where: i.date < ^date)
-
-    if has_older do
-      Phoenix.Controller.current_path(conn, %{before: id})
-    else
-      nil
-    end
-  end
-
-  @spec prev_page_path(Plug.Conn.t(), [Frenzy.Item.t()]) :: String.t() | nil
-  def prev_page_path(_conn, []), do: nil
-
-  def prev_page_path(conn, [%Item{id: id, date: date} | _]) do
-    has_newer = Repo.exists?(from i in Item, where: i.date > ^date)
-
-    if has_newer do
-      Phoenix.Controller.current_path(conn, %{after: id})
-    else
-      nil
-    end
-  end
 end

lib/frenzy_web/views/group_view.ex

@@ -1,6 +1,3 @@
 defmodule FrenzyWeb.GroupView do
   use FrenzyWeb, :view
-
-  defdelegate next_page_path(conn, items), to: FrenzyWeb.FeedView
-  defdelegate prev_page_path(conn, items), to: FrenzyWeb.FeedView
 end