WIP

lib/ash_phoenix/form/auto.ex

@@ -49,12 +49,11 @@ defmodule AshPhoenix.Form.Auto do
   if you are using liveview, you could actually look up the record using the input from the read action, and then use `AshPhoenix.Form.update_form/3`
   to set that looked up record as the data of the `_update` form.
 
-  ### Many to Many Relationshisp
+  ### Many to Many Relationships
 
   In the case that a manage_change option points to a join relationship, that form is presented via a special nested form called
   `_join`. So the first form in `inputs_for(form, :relationship)` would be for the destination, and then inside of that you could say
   `inputs_for(nested_form, :_join)`. The parameters are merged together during submission.
-
   """
 
   @dialyzer {:nowarn_function, rel_to_resource: 2}

lib/ash_phoenix/form/form.ex

@@ -848,6 +848,9 @@ defmodule AshPhoenix.Form do
 
               new_forms =
                 Enum.reduce(form_params, forms, fn {index, params}, forms ->
+                  if params["_ignore"] == "true" do
+                    Map.put_new(forms, key, [])
+                  else
                     case Enum.find(form.forms[key] || [], &matcher.(&1, params, form, key, index)) do
                       nil ->
                         create_action =
@@ -888,6 +891,7 @@ defmodule AshPhoenix.Form do
                             [validated]
                         end)
                     end
+                  end
                 end)
 
               if Map.has_key?(new_forms, opts[:as] || key) do
@@ -897,6 +901,9 @@ defmodule AshPhoenix.Form do
               else
                 new_forms
               end
+            else
+              if form_params["_ignore"] == "true" do
+                Map.put_new(forms, key, nil)
               else
                 if form.forms[key] do
                   new_form =
@@ -929,6 +936,7 @@ defmodule AshPhoenix.Form do
                   Map.put(forms, key, new_form)
                 end
               end
+            end
 
           _ ->
             case opts[:type] do
@@ -2847,6 +2855,7 @@ defmodule AshPhoenix.Form do
          transform_errors
        ) do
     if (opts[:type] || :single) == :single do
+      if map(form_params)["_ignore"] != "true" do
         if map(form_params)["_form_type"] == "read" do
           read_action =
             opts[:read_action] ||
@@ -2890,9 +2899,13 @@ defmodule AshPhoenix.Form do
             id: id <> "_#{key}"
           )
         end
+      end
     else
       form_params
       |> indexed_list()
+      |> Enum.reject(fn {form_params, _} ->
+        map(form_params)["_ignore"] == "true"
+      end)
       |> Enum.with_index()
       |> Enum.map(fn {{form_params, original_index}, index} ->
         if map(form_params)["_form_type"] == "read" do
@@ -2965,6 +2978,7 @@ defmodule AshPhoenix.Form do
       end
 
     if (opts[:type] || :single) == :single do
+      if map(form_params)["_ignore"] != "true" do
         if data do
           case map(form_params)["_form_type"] || "update" do
             "update" ->
@@ -3051,6 +3065,7 @@ defmodule AshPhoenix.Form do
               raise "unexpected form type for form with no data #{other} with params: #{inspect(form_params)}"
           end
         end
+      end
     else
       data = List.wrap(data)
 
@@ -3059,6 +3074,15 @@ defmodule AshPhoenix.Form do
       |> Enum.with_index()
       |> Enum.reduce({[], List.wrap(data)}, fn {{form_params, original_index}, index},
                                                {forms, data} ->
+        if form_params["_ignore"] == true do
+          case data do
+            [_item | rest] ->
+              {forms, rest}
+
+            _ ->
+              {forms, data}
+          end
+        else
           if map(form_params)["_form_type"] == "read" do
             resource =
               opts[:read_resource] || opts[:resource] ||
@@ -3174,6 +3198,7 @@ defmodule AshPhoenix.Form do
                 {[form | forms], []}
             end
           end
+        end
       end)
       |> elem(0)
       |> Enum.reverse()

test/form_test.exs

@@ -117,6 +117,45 @@ defmodule AshPhoenix.FormTest do
     assert Form.params(form) == %{"comments" => [%{"id" => comment.id}]}
   end
 
+  test "ignoring a form filters it from the parameters" do
+    post =
+      Post
+      |> Ash.Changeset.new(%{text: "post"})
+      |> Api.create!()
+
+    comment =
+      Comment
+      |> Ash.Changeset.new(%{text: "comment"})
+      |> Ash.Changeset.replace_relationship(:post, post)
+      |> Api.create!()
+
+    form =
+      post
+      |> Form.for_update(:update_with_replace,
+        api: Api,
+        forms: [
+          comments: [
+            read_resource: Comment,
+            type: :list,
+            read_action: :read,
+            data: [comment]
+          ]
+        ]
+      )
+
+    assert [comment_form] = inputs_for(form_for(form, "blah"), :comments)
+
+    assert Phoenix.HTML.Form.input_value(comment_form, :text) == "comment"
+
+    form = Form.validate(form, %{"comments" => [%{"id" => comment.id, "_ignore" => "true"}]})
+
+    assert Form.params(form) == %{"comments" => []}
+
+    form = Form.validate(form, %{"comments" => [%{"id" => comment.id, "_ignore" => "false"}]})
+
+    assert Form.params(form) == %{"comments" => [%{"id" => comment.id}]}
+  end
+
   describe "the .changed? field is updated as data changes" do
     test "it is false for a create form with no changes" do
       form =