Remove nil fields in request params

lib/nadia.ex

@@ -512,7 +512,7 @@ defmodule Nadia do
   def get_chat_member(chat_id, user_id) do
     request("getChatMember", chat_id: chat_id, user_id: user_id)
   end
-  
+
   @doc """
   Use this method to send answers to callback queries sent from inline keyboards.
   The answer will be displayed to the user as a notification at the top of the chat
@@ -630,13 +630,7 @@ defmodule Nadia do
   """
   @spec answer_inline_query(binary, [Nadia.Model.InlineQueryResult.t], [{atom, any}]) :: :ok | {:error, Error.t}
   def answer_inline_query(inline_query_id, results, options \\ []) do
-    encoded_results = results
-    |> Enum.map(fn result ->
-         for {k, v} <- Map.from_struct(result), v != nil, into: %{}, do: {k, v}
-       end)
-    |> Poison.encode!
-    args = [inline_query_id: inline_query_id, results: encoded_results]
-
+    args = [inline_query_id: inline_query_id, results: results]
     request("answerInlineQuery", args ++ options)
   end
 end

lib/nadia/api.ex

@@ -40,14 +40,31 @@ defmodule Nadia.API do
   defp build_request(params, file_field) do
     params = params
     |> Keyword.update(:reply_markup, nil, &(Poison.encode!(&1)))
-    |> Enum.filter_map(fn {_, v} -> v end, fn {k, v} -> {k, to_string(v)} end)
+    |> Enum.filter_map(fn {_, v} -> v end, fn {k, v} -> {k, drop_nil_fields(v)} end)
     if !is_nil(file_field) and File.exists?(params[file_field]) do
       build_multipart_request(params, file_field)
     else
       {:form, params}
     end
   end
 
+  defp drop_nil_fields(value) when is_list(value) do
+    value
+    |> Enum.map(fn value ->
+         for {k, v} <- Map.from_struct(value), v != nil, into: %{}, do: {k, drop_nil_fields(v)}
+       end)
+    |> Poison.encode!
+  end
+
+  defp drop_nil_fields(value) when is_map(value) do
+    value
+    |> Map.from_struct
+    |> Enum.filter(fn {_, v} -> v != nil end)
+    |> Enum.into(%{})
+  end
+
+  defp drop_nil_fields(value), do: to_string(value)
+
   @doc """
   Generic method to call Telegram Bot API.