Merge pull request #78 from epochtalk/validate-mutually-exclusive

Validate mutually exclusive

Author: unenglishable

lib/epochtalk_server_web/controllers/post.ex

@@ -151,14 +151,14 @@ defmodule EpochtalkServerWeb.Controllers.Post do
   """
   # TODO(akinsey): Implement for completion
   # - parser
-  # - Implement guard in Validate that prevents passing in page and start at the same time
   def by_thread(conn, attrs) do
     # Parameter Validation
     with thread_id <- Validate.cast(attrs, "thread_id", :integer, required: true),
          page <- Validate.cast(attrs, "page", :integer, default: 1, min: 1),
          start <- Validate.cast(attrs, "start", :integer, min: 1),
          limit <- Validate.cast(attrs, "limit", :integer, default: 25, min: 1, max: 100),
          desc <- Validate.cast(attrs, "desc", :boolean, default: true),
+         :ok <- Validate.mutually_exclusive!(attrs, ["page", "start"]),
          user <- Guardian.Plug.current_resource(conn),
          user_priority <- ACL.get_user_priority(conn),
 

lib/epochtalk_server_web/controllers/thread.ex

@@ -43,9 +43,7 @@ defmodule EpochtalkServerWeb.Controllers.Thread do
   # TODO(akinsey): Post pre processing, authorizations, image processing, hooks. Things to consider:
   # - does html sanitizer need to run on the front end too
   # - how do we run the same parser/sanitizer on the elixir back end as the node frontend
-  # - processing mentions
   # - does createImageReferences need to be called here? was this missing from the old code?
-  # - does updateUserActivity need to be called here? was this missing from the old code?
   def create(conn, attrs) do
     # authorization checks
     with :ok <- ACL.allow!(conn, "threads.create"),

lib/epochtalk_server_web/errors/custom_errors.ex

@@ -49,6 +49,7 @@ defmodule EpochtalkServerWeb.CustomErrors do
     def exception(value) do
       case value do
         [] -> %InvalidPayload{}
+        [message: message] -> %InvalidPayload{message: message}
         _ -> %InvalidPayload{message: gen_message(Enum.into(value, %{required: false}))}
       end
     end

lib/epochtalk_server_web/helpers/validate.ex

@@ -6,6 +6,20 @@ defmodule EpochtalkServerWeb.Helpers.Validate do
   """
   alias EpochtalkServerWeb.CustomErrors.InvalidPayload
 
+  @doc """
+  Ensure that `keys` provided in list are mutually exclusive within `attrs` map.
+  """
+  @spec mutually_exclusive!(attrs :: map, keys :: [String.t()]) :: :ok | no_return
+  def mutually_exclusive!(attrs, keys) when is_map(attrs) and is_list(keys) do
+    if map_contains_any_two_keys_in_list?(attrs, keys),
+      do:
+        raise(InvalidPayload,
+          message:
+            "The following payload parameters cannot be passed at the same time: #{Enum.join(keys, ", ")}"
+        ),
+      else: :ok
+  end
+
   @doc """
   Helper used to validate and cast request parameters directly out of the incoming
   paylod map (usually a controller function's `attrs` parameter) to the specified type.
@@ -121,6 +135,29 @@ defmodule EpochtalkServerWeb.Helpers.Validate do
     end
   end
 
+  # entrypoint
+  defp map_contains_any_two_keys_in_list?(map, list),
+    do: map_contains_any_two_keys_in_list?(map, list, false)
+
+  # if map is empty, return false
+  defp map_contains_any_two_keys_in_list?(map, _list, _key_found?) when map == %{}, do: false
+  # if list is empty, return false
+  defp map_contains_any_two_keys_in_list?(_map, [], _key_found?), do: false
+  # if key_found? is false
+  defp map_contains_any_two_keys_in_list?(map, [key | keys] = _list, false = _key_found?) do
+    # check next key with updated key_found?
+    map_contains_any_two_keys_in_list?(map, keys, Map.has_key?(map, key))
+  end
+
+  # if key_found? is true
+  defp map_contains_any_two_keys_in_list?(map, [key | keys] = _list, true = key_found?) do
+    # if current key is in map, return true
+    if Map.has_key?(map, key),
+      do: true,
+      # otherwise, check next key
+      else: map_contains_any_two_keys_in_list?(map, keys, key_found?)
+  end
+
   defp to_bool(str, opts) do
     case str do
       "true" -> true

test/epochtalk_server_web/helpers/validate_test.exs

@@ -1,5 +1,56 @@
 defmodule Test.EpochtalkServerWeb.Helpers.Validate do
   use Test.Support.ConnCase, async: true
   alias EpochtalkServerWeb.Helpers.Validate
+  alias EpochtalkServerWeb.CustomErrors.InvalidPayload
   doctest Validate
+
+  describe "mutually_exclusive/2" do
+    test "given cases, returns correct result" do
+      cases = [
+        %{
+          attrs: %{"page" => 1},
+          keys: ["page", "start"],
+          result: :ok
+        },
+        %{
+          attrs: %{"start" => 1},
+          keys: ["page", "start"],
+          result: :ok
+        },
+        %{
+          attrs: %{"start" => 1},
+          keys: ["start"],
+          result: :ok
+        },
+        %{
+          attrs: %{"page" => 1, "start" => 1},
+          keys: ["page", "start"],
+          result: :error
+        },
+        %{
+          attrs: %{"page" => 1, "start" => 1, "stop" => 1},
+          keys: ["page", "start"],
+          result: :error
+        },
+        %{
+          attrs: %{"page" => 1, "stop" => 1},
+          keys: ["page", "start", "stop", "enter"],
+          result: :error
+        }
+      ]
+
+      cases
+      |> Enum.each(fn
+        %{attrs: attrs, keys: keys, result: :error} ->
+          assert_raise InvalidPayload,
+                       ~r/^The following payload parameters cannot be passed at the same time:/,
+                       fn ->
+                         Validate.mutually_exclusive!(attrs, keys)
+                       end
+
+        %{attrs: attrs, keys: keys, result: :ok} ->
+          assert Validate.mutually_exclusive!(attrs, keys) == :ok
+      end)
+    end
+  end
 end