improvement: add error hints for NoFormConfigured errors

lib/ash_phoenix/form/form.ex

@@ -3233,6 +3233,8 @@ defmodule AshPhoenix.Form do
   defp do_remove_form(form, [key], trail) when not is_integer(key) do
     unless form.form_keys[key] do
       raise AshPhoenix.Form.NoFormConfigured,
+        resource: form.resource,
+        action: form.action,
         field: key,
         available: Keyword.keys(form.form_keys || []),
         path: Enum.reverse(trail)
@@ -3277,6 +3279,8 @@ defmodule AshPhoenix.Form do
   defp do_remove_form(form, [key, i], trail) when is_integer(i) do
     unless form.form_keys[key] do
       raise AshPhoenix.Form.NoFormConfigured,
+        resource: form.resource,
+        action: form.action,
         field: key,
         available: Keyword.keys(form.form_keys || []),
         path: Enum.reverse(trail)
@@ -3319,6 +3323,8 @@ defmodule AshPhoenix.Form do
   defp do_remove_form(form, [key, i | rest], trail) when is_integer(i) do
     unless form.form_keys[key] do
       raise AshPhoenix.Form.NoFormConfigured,
+        resource: form.resource,
+        action: form.action,
         field: key,
         available: Keyword.keys(form.form_keys || []),
         path: Enum.reverse(trail)
@@ -3337,6 +3343,8 @@ defmodule AshPhoenix.Form do
   defp do_remove_form(form, [key | rest], trail) do
     unless form.form_keys[key] do
       raise AshPhoenix.Form.NoFormConfigured,
+        resource: form.resource,
+        action: form.action,
         field: key,
         available: Keyword.keys(form.form_keys || []),
         path: Enum.reverse(trail)
@@ -3357,6 +3365,8 @@ defmodule AshPhoenix.Form do
   defp do_add_form(form, [key, i | rest], opts, trail, transform_errors) when is_integer(i) do
     unless form.form_keys[key] do
       raise AshPhoenix.Form.NoFormConfigured,
+        resource: form.resource,
+        action: form.action,
         field: key,
         available: Keyword.keys(form.form_keys || []),
         path: Enum.reverse(trail)
@@ -3389,6 +3399,8 @@ defmodule AshPhoenix.Form do
     config =
       form.form_keys[key] ||
         raise AshPhoenix.Form.NoFormConfigured,
+          resource: form.resource,
+          action: form.action,
           field: key,
           available: Keyword.keys(form.form_keys || []),
           path: Enum.reverse(trail)
@@ -3478,6 +3490,8 @@ defmodule AshPhoenix.Form do
   defp do_add_form(form, [key | rest], opts, trail, transform_errors) do
     unless form.form_keys[key] do
       raise AshPhoenix.Form.NoFormConfigured,
+        resource: form.resource,
+        action: form.action,
         field: key,
         available: Keyword.keys(form.form_keys || []),
         path: Enum.reverse(trail)
@@ -4739,6 +4753,8 @@ defmodule AshPhoenix.Form do
     def to_form(form, _phoenix_form, field, opts) do
       unless Keyword.has_key?(form.form_keys, field) do
         raise AshPhoenix.Form.NoFormConfigured,
+          resource: form.resource,
+          action: form.action,
           field: field,
           available: Keyword.keys(form.form_keys || [])
       end

lib/ash_phoenix/form/no_form_configured.ex

@@ -1,12 +1,18 @@
 defmodule AshPhoenix.Form.NoFormConfigured do
   @moduledoc "Raised when attempting to refer to a form but no nested form with that name was configured."
-  defexception [:field, :available, :path]
+  defexception [:field, :available, :path, :action, :resource]
 
   def exception(opts) do
-    %__MODULE__{field: opts[:field], available: opts[:available], path: List.wrap(opts[:paths])}
+    %__MODULE__{
+      field: opts[:field],
+      available: opts[:available],
+      path: List.wrap(opts[:paths]),
+      action: Ash.Resource.Info.action(opts[:resource], opts[:action]),
+      resource: opts[:resource]
+    }
   end
 
-  def message(%{field: field, available: available, path: path}) do
+  def message(%{field: field, available: available, path: path} = error) do
     path_message =
       if path do
         "at path #{inspect(path)}"
@@ -16,6 +22,7 @@ defmodule AshPhoenix.Form.NoFormConfigured do
 
     """
     #{field} #{path_message} must be configured in the form to be used with `inputs_for`. For example:
+    #{hint(error)}
 
     Available forms:
 
@@ -55,4 +62,52 @@ defmodule AshPhoenix.Form.NoFormConfigured do
         )
     """
   end
+
+  defp hint(error) do
+    cond do
+      argument = Enum.find(error.action.arguments, &(&1.name == error.field)) ->
+        """
+
+        There is an argument called `#{argument.name}` on the action `#{inspect(error.resource)}.#{error.action.name}`.
+
+        Perhaps you are missing a `change manage_relationship` for that argument, or it is not a type that can have forms generated for it?
+        """
+
+      attribute = Ash.Resource.Info.attribute(error.resource, error.field) ->
+        if attribute.name in error.action.accept do
+          """
+
+          There is a attribute called `#{attribute.name}` on the resource `#{inspect(error.resource)}`,  but it is
+          not accepted by `#{inspect(error.resource)}.#{error.action.name}`.
+
+          Perhaps you meant to add that attribute to the `accept` list, or you meant to make it `public? true`?
+          """
+        else
+          """
+
+          There is a attribute called `#{attribute.name}` on the resource `#{inspect(error.resource)}`,  and it is
+          accepted by `#{inspect(error.resource)}.#{error.action.name}`.
+
+          Perhaps it is not a type that can have forms generated for it?
+          """
+        end
+
+      relationship = Ash.Resource.Info.attribute(error.resource, error.field) ->
+        """
+
+        There is a relationship called `#{relationship.name}` on the resource `#{inspect(error.resource)}`.
+
+        Perhaps you are missing an argument with `change manage_relationship` in the
+        action #{inspect(error.resource)}.#{error.action.name}?
+        """
+
+      true ->
+        """
+        There is a no attribute or relationship called `#{error.field}` on the resource `#{inspect(error.resource)}`, and
+        no argument called `#{error.field}` on `#{inspect(error.resource)}.#{error.action.name}`.
+
+        Perhaps you have a typo?
+        """
+    end
+  end
 end

test/form_test.exs

@@ -1201,18 +1201,19 @@ defmodule AshPhoenix.FormTest do
   end
 
   describe "`inputs_for` with no configuration" do
-    # phoenix changes make this not work anymore
-    # test "it should raise an error" do
-    #   form =
-    #     Post
-    #     |> Form.for_create(:create)
-    #     |> Form.validate(%{text: "text"})
-    #     |> form_for("action")
+    test "it should raise an error" do
+      form =
+        Post
+        |> Form.for_create(:create)
+        |> Form.validate(%{text: "text"})
+        |> form_for("action")
 
-    #   assert_raise AshPhoenix.Form.NoFormConfigured, fn ->
-    #     inputs_for(form, :post) == []
-    #   end
-    # end
+      assert_raise AshPhoenix.Form.NoFormConfigured,
+                   ~r/There is a no attribute or relationship called `post` on the resource `AshPhoenix.Test.Post`/,
+                   fn ->
+                     AshPhoenix.Form.add_form(form, :post)
+                   end
+    end
   end
 
   describe "inputs_for` relationships" do