From bb39ba3f03cd4bd835e5da784cb7cbd7f134766f Mon Sep 17 00:00:00 2001
From: Amos King <amos.l.king@gmail.com>
Date: Mon, 20 Feb 2023 17:32:04 -0600
Subject: [PATCH] Fixes default values on dead forms (#74)

---
 lib/ash_phoenix/form/form.ex                | 49 ++++++++++++++++++++-
 lib/ash_phoenix/live_view.ex                |  1 +
 test/form_test.exs                          | 34 ++++++++++++++
 test/support/resources/post_with_default.ex |  1 +
 4 files changed, 84 insertions(+), 1 deletion(-)

diff --git a/lib/ash_phoenix/form/form.ex b/lib/ash_phoenix/form/form.ex
index 45bd6bf..bc4b9b5 100644
--- a/lib/ash_phoenix/form/form.ex
+++ b/lib/ash_phoenix/form/form.ex
@@ -283,6 +283,16 @@ defmodule AshPhoenix.Form do
       type: :string,
       doc:
         "The http method to associate with the form. Defaults to `post` for creates, and `put` for everything else."
+    ],
+    exclude_fields_if_empty: [
+      type: {:list, {:or, [:atom, :string, {:tuple, [:any, :any]}]}},
+      doc: """
+      These fields will be ignored if they are empty strings.
+
+      This list of fields supports dead view forms. When a form is submitted from dead view
+      empty fields are submitted as empty strings. This is problematic for fields that allow_nil
+      or those that have default values.
+      """
     ]
   ]
 
@@ -2199,6 +2209,7 @@ defmodule AshPhoenix.Form do
     form = to_form!(form)
     # These options aren't documented because they are still experimental
     hidden? = Keyword.get(opts, :hidden?, true)
+    excluded_empty_fields = Keyword.get(opts, :exclude_fields_if_empty, Keyword.get(form.opts, :exclude_fields_if_empty, []))
     indexer = opts[:indexer]
     indexed_lists? = opts[:indexed_lists?] || not is_nil(indexer) || false
     transform = opts[:transform]
@@ -2214,7 +2225,10 @@ defmodule AshPhoenix.Form do
       |> Keyword.keys()
       |> Enum.flat_map(&[&1, to_string(&1)])
 
-    params = Map.drop(form.params, form_keys)
+    params =
+      form.params
+      |> Map.drop(form_keys)
+      |> exclude_empty_fields(excluded_empty_fields)
 
     params =
       if only_touched? do
@@ -2245,6 +2259,7 @@ defmodule AshPhoenix.Form do
             nested_form = form.forms[key]
 
             if nested_form && filter.(nested_form) do
+              opts = Keyword.put(opts, :exclude_fields_if_empty, Keyword.get(excluded_empty_fields, key, []))
               nested_params = params(nested_form, opts)
 
               if nested_params["_ignore"] == "true" do
@@ -4158,6 +4173,38 @@ defmodule AshPhoenix.Form do
   defp form_for_method(:create), do: "post"
   defp form_for_method(_), do: "put"
 
+  defp exclude_empty_fields(params, []) do
+    params
+  end
+
+  defp exclude_empty_fields(params, _) when params == %{} do
+    params
+  end
+
+  defp exclude_empty_fields(params, [unset_key | rest]) when is_atom(unset_key) do
+    {_, new} =
+      Map.get_and_update(params, to_string(unset_key), fn
+        "" -> :pop
+        nil -> :pop
+        value -> {value, value}
+      end)
+
+    exclude_empty_fields(new, rest)
+  end
+
+  defp exclude_empty_fields(params, [{nested_type, nested_keys} | rest]) do
+    {_, new} =
+      Map.get_and_update(params, to_string(nested_type), fn
+        nil ->
+          :pop
+
+        map ->
+          {map, exclude_empty_fields(map, nested_keys)}
+      end)
+
+    exclude_empty_fields(new, rest)
+  end
+
   defimpl Phoenix.HTML.FormData do
     import AshPhoenix.FormData.Helpers
 
diff --git a/lib/ash_phoenix/live_view.ex b/lib/ash_phoenix/live_view.ex
index b174386..0baa9b0 100644
--- a/lib/ash_phoenix/live_view.ex
+++ b/lib/ash_phoenix/live_view.ex
@@ -600,6 +600,7 @@ defmodule AshPhoenix.LiveView do
           Phoenix.LiveView.assign(socket, one, two)
         end
       end
+
     {:error, :nofile} ->
       defp assign(%Phoenix.LiveView.Socket{} = socket, one, two) do
         Phoenix.LiveView.assign(socket, one, two)
diff --git a/test/form_test.exs b/test/form_test.exs
index 917287c..1b9c232 100644
--- a/test/form_test.exs
+++ b/test/form_test.exs
@@ -191,6 +191,40 @@ defmodule AshPhoenix.FormTest do
     assert form.valid? == false
   end
 
+  test "blank form values unset - helps support dead view forms" do
+    form =
+      Form.for_create(PostWithDefault, :create, api: Api, exclude_fields_if_empty: [:text, :title])
+
+    {:ok, post} = Form.submit(form, params: %{"title" => "", "text" => "bar"})
+    assert post.text == "bar"
+    assert post.title == nil
+  end
+
+  test "blank nested form values unset - helps support dead view forms" do
+    form =
+      Comment
+      |> Form.for_create(:create,
+        api: Api,
+        forms: [
+          post: [
+            resource: PostWithDefault,
+            create_action: :create
+          ]
+        ],
+        exclude_fields_if_empty: [post: [:title, :description]]
+      )
+      |> Form.add_form(:post)
+
+    {:ok, comment} =
+      Form.submit(form,
+        params: %{"text" => "comment", "post" => %{"title" => "", "text" => "bar"}}
+      )
+
+    post = comment.post
+    assert post.text == "bar"
+    assert post.title == nil
+  end
+
   test "phoenix forms are accepted as input in some cases" do
     form = Form.for_create(PostWithDefault, :create, api: Api)
     form = AshPhoenix.Form.validate(form, %{"text" => ""}, errors: form.submitted_once?)
diff --git a/test/support/resources/post_with_default.ex b/test/support/resources/post_with_default.ex
index a6d55f5..db1e24d 100644
--- a/test/support/resources/post_with_default.ex
+++ b/test/support/resources/post_with_default.ex
@@ -13,5 +13,6 @@ defmodule AshPhoenix.Test.PostWithDefault do
   attributes do
     uuid_primary_key(:id)
     attribute(:text, :string, allow_nil?: false, default: "foo")
+    attribute(:title, :string)
   end
 end