Fix Elixir 1.3 warnings (#21)

* Fix Elixir 1.3 warnings
* Made some other small refactorings for clarity

Tests are still passing but not sure if every case was covered.

* Depipeline single function calls

* Add a note about `after` keyword

* Refactoring for clarity

Author: Josh Price

lib/graphql/relay/connection/ecto.ex

@@ -11,21 +11,25 @@ if Code.ensure_loaded?(Ecto) do
 
     def resolve(query, %{repo: repo} = args) do
       before = cursor_to_offset(args[:before])
+      # `after` is a keyword http://elixir-lang.org/docs/master/elixir/Kernel.SpecialForms.html#try/1
       a_after = cursor_to_offset(args[:after])
       first = args[:first]
       last = args[:last]
       limit = Enum.min([first, last, connection_count(repo, query)])
 
-      if a_after do
-        query = from things in query, where: things.id > ^a_after
+      query = if a_after do
+        from things in query, where: things.id > ^a_after
+      else
+        query
       end
 
-      if before do
-        query = from things in query, where: things.id < ^before
+      query = if before do
+        from things in query, where: things.id < ^before
+      else
+        query
       end
 
-      # Calculate has_next_page/has_prev_page before order_by to avoid group_by
-      # requirement
+      # Calculate has_next_page/has_prev_page before order_by to avoid group_by requirement
       has_next_page = case first do
         nil -> false
         _ ->
@@ -44,16 +48,16 @@ if Code.ensure_loaded?(Ecto) do
           repo.one(has_prev_records_query) > last
       end
 
-      if first do
-        query = from things in query, order_by: [asc: things.id], limit: ^limit
+      query = if first do
+        from things in query, order_by: [asc: things.id], limit: ^limit
       else
-        has_next_page = false
+        query
       end
 
-      if last do
-        query = from things in query, order_by: [desc: things.id], limit: ^limit
+      query = if last do
+        from things in query, order_by: [desc: things.id], limit: ^limit
       else
-        has_prev_page = false
+        query
       end
 
       records = repo.all(query)
@@ -66,10 +70,8 @@ if Code.ensure_loaded?(Ecto) do
       end)
 
       edges = case last do
-        nil ->
-          edges
-        _ ->
-          Enum.reverse(edges)
+        nil -> edges
+        _ -> Enum.reverse(edges)
       end
 
       first_edge = List.first(edges)
@@ -78,34 +80,22 @@ if Code.ensure_loaded?(Ecto) do
       %{
         edges: edges,
         pageInfo: %{
-          startCursor: first_edge && Map.get(first_edge, :cursor) || nil,
-          endCursor: last_edge && Map.get(last_edge, :cursor) || nil,
+          startCursor: first_edge && Map.get(first_edge, :cursor),
+          endCursor: last_edge && Map.get(last_edge, :cursor),
           hasPreviousPage: has_prev_page,
           hasNextPage: has_next_page
         }
       }
     end
 
-    def get_offset_with_default(cursor, default_offset) do
-      unless cursor do
-        default_offset
-      else
-        offset = cursor_to_offset(cursor)
-        offset || default_offset
-      end
-    end
-
+    def cursor_to_offset(nil), do: nil
     def cursor_to_offset(cursor) do
-      case cursor do
-        nil -> nil
-        _ ->
-          case Base.decode64(cursor) do
-            {:ok, decoded_cursor} ->
-              {int, _} = Integer.parse(String.slice(decoded_cursor, String.length(@prefix)..String.length(decoded_cursor)))
-              int
-            :error ->
-              nil
-          end
+      case Base.decode64(cursor) do
+        {:ok, decoded_cursor} ->
+          {int, _} = Integer.parse(String.slice(decoded_cursor, String.length(@prefix)..String.length(decoded_cursor)))
+          int
+        :error ->
+          nil
       end
     end
 
@@ -121,20 +111,20 @@ if Code.ensure_loaded?(Ecto) do
 
     defp make_query_countable(query) do
       query
-        |> remove_select
-        |> remove_order
+      |> remove_select
+      |> remove_order
     end
 
     # Remove select if it exists so that we avoid `only one select
     # expression is allowed in query` Ecto exception
     defp remove_select(query) do
-      query |> Ecto.Query.exclude(:select)
+      Ecto.Query.exclude(query, :select)
     end
 
     # Remove order by if it exists so that we avoid `field X in "order_by"
     # does not exist in the model source in query`
     defp remove_order(query) do
-      query |> Ecto.Query.exclude(:order_by)
+      Ecto.Query.exclude(query, :order_by)
     end
   end
 end

lib/graphql/relay/connection/list.ex

@@ -1,9 +1,7 @@
 defmodule GraphQL.Relay.Connection.List do
   @prefix "arrayconnection:"
 
-  def resolve(data) do
-    resolve(data, %{})
-  end
+  def resolve(data), do: resolve(data, %{})
   def resolve(data, args) do
     resolve_slice(data, args, %{
       slice_start: 0,
@@ -13,34 +11,40 @@ defmodule GraphQL.Relay.Connection.List do
 
   def resolve_slice(records, args, meta) do
     before = args[:before]
+    # `after` is a keyword http://elixir-lang.org/docs/master/elixir/Kernel.SpecialForms.html#try/1
     a_after = args[:after]
     first = args[:first]
     last = args[:last]
     slice_start = meta[:slice_start] || 0
     list_length = meta[:list_length] || length(records)
     slice_end = slice_start + length(records)
-    before_offset = get_offset_with_default(before, list_length)
-    after_offset = get_offset_with_default(a_after, -1)
+    before_offset = cursor_to_offset(before, list_length)
+    after_offset = cursor_to_offset(a_after, -1)
     start_offset = Enum.max([slice_start - 1, after_offset, -1]) + 1
     end_offset = Enum.min([slice_end, before_offset, list_length])
 
-    if first do
-      end_offset = Enum.min([end_offset, start_offset + first])
+    end_offset = if first do
+      Enum.min([end_offset, start_offset + first])
+    else
+      end_offset
     end
 
-    if last do
-      start_offset = Enum.max([start_offset, end_offset - last])
+    start_offset = if last do
+      Enum.max([start_offset, end_offset - last])
+    else
+      start_offset
     end
 
     from_slice = Enum.max([start_offset - slice_start, 0])
     to_slice = length(records) - (slice_end - end_offset) - 1
     slice = case first do
       0 -> []
-      _ ->
-        Enum.slice(records, from_slice..to_slice)
+      _ -> Enum.slice(records, from_slice..to_slice)
     end
 
-    {edges, _count} = Enum.map_reduce(slice, 0, fn(record, acc) -> {%{ cursor: offset_to_cursor(start_offset+acc), node: record }, acc + 1} end)
+    {edges, _count} = Enum.map_reduce(slice, 0, fn(record, acc) ->
+      {%{cursor: offset_to_cursor(start_offset+acc), node: record}, acc + 1}
+    end)
 
     first_edge = List.first(edges)
     last_edge = List.last(edges)
@@ -50,42 +54,31 @@ defmodule GraphQL.Relay.Connection.List do
     %{
       edges: edges,
       pageInfo: %{
-        startCursor: first_edge && Map.get(first_edge, :cursor) || nil,
-        endCursor: last_edge && Map.get(last_edge, :cursor) || nil,
+        startCursor: first_edge && Map.get(first_edge, :cursor),
+        endCursor: last_edge && Map.get(last_edge, :cursor),
         hasPreviousPage: last && (start_offset > lower_bound) || false,
         hasNextPage: first && (end_offset < upper_bound) || false
       }
     }
   end
 
-  def get_offset_with_default(cursor, default_offset) do
-    unless cursor do
-      default_offset
-    else
-      offset = cursor_to_offset(cursor)
-      offset || default_offset
-    end
-  end
-
-  def cursor_to_offset(cursor) do
+  def cursor_to_offset(nil, default), do: default
+  def cursor_to_offset(cursor, default) do
     case Base.decode64(cursor) do
       {:ok, decoded_cursor} ->
         {int, _} = Integer.parse(String.slice(decoded_cursor, String.length(@prefix)..String.length(decoded_cursor)))
         int
       :error ->
-        nil
+        default
     end
   end
 
   def cursor_for_object_in_connection(data, object) do
     offset = Enum.find_index(data, fn(obj) -> object == obj end)
-    unless offset do
-      nil
-    else
-      offset_to_cursor(offset)
-    end
+    offset_to_cursor(offset)
   end
 
+  def offset_to_cursor(nil), do: nil
   def offset_to_cursor(offset) do
     Base.encode64("#{@prefix}#{offset}")
   end

lib/graphql_relay.ex

@@ -6,13 +6,8 @@ defmodule GraphQL.Relay do
   """
 
   @spec resolve_maybe_thunk(fun | map) :: %{}
-  def resolve_maybe_thunk(thing_or_thunk) do
-    if Kernel.is_function(thing_or_thunk) do
-      thing_or_thunk.()
-    else
-      thing_or_thunk
-    end
-  end
+  def resolve_maybe_thunk(t) when is_function(t), do: t.()
+  def resolve_maybe_thunk(t), do: t
 
   def generate_schema_json! do
     Logger.debug "Updating GraphQL schema.json"