WIP 20250517-1158

Author: jechol

README.md

@@ -15,7 +15,7 @@ defmodule MyApp.Post do
     attribute :author, :string, allow_nil?: false
     attribute :title, :string, allow_nil?: false
     attribute :content, :string, allow_nil?: true
-    attriubte :tag, :string, allow_nil?: true, default: "JS"
+    attriubte :tag, :string, allow_nil?: false, default: "JS"
   end
 
   random_params do
@@ -41,9 +41,21 @@ Post.random_params!(:create, %{author: "James"}, %{
 })
 ```
 
-### Options
+### Default Behavior
+
+By default, it generates random values for attributes and arguments that have `allow_nil?: false` and no default value (`default == nil`). In the example above, `author` and `title` fall into this category.
+
+### Belongs To Relationships
 
-By default, it generates random values for attributes and arguments that have `allow_nil?: false` and no default value (`default == nil`).
+For attributes and arguments that match the `name` or `source_attribute` of a `belongs_to` relationship:
+- In `create` actions, they are generated with `nil` values
+- In other actions, they are not generated at all
+
+This behavior exists because:
+- In `create` actions, omitting a value is equivalent to setting it to `nil`
+- In `update` actions, omitting a value preserves the existing relationship, while explicitly setting it to `nil` removes the relationship
+
+### Options
 
 - `populate`: Forces generation of random values for specified attributes/arguments, overriding the default behavior
 - `omit`: Prevents generation of random values for specified attributes/arguments, overriding the default behavior

test/ash_random_params_test.exs

@@ -21,7 +21,17 @@ defmodule AshRandomParamsTest do
     end
 
     actions do
-      defaults [:read, :destroy, create: :*, update: :*]
+      defaults [:read, :destroy]
+
+      create :create do
+        accept :*
+        argument :author, :struct, allow_nil?: false, constraints: [instance_of: Author]
+      end
+
+      update :update do
+        accept :*
+        argument :author, :struct, allow_nil?: false, constraints: [instance_of: Author]
+      end
     end
 
     relationships do
@@ -76,15 +86,15 @@ defmodule AshRandomParamsTest do
     end
   end
 
-  test "with no options" do
+  test "create action" do
     assert %{
+             author: nil,
              author_id: nil,
              req_str: "req_str-" <> _,
              opt_str: nil,
              req_int: 777,
              opt_int: 123
            } =
-             params =
              Post
              |> Ash.ActionInput.for_action(
                :random_params,
@@ -93,8 +103,27 @@ defmodule AshRandomParamsTest do
                }
              )
              |> Ash.run_action!()
+  end
+
+  test "update action" do
+    assert %{
+             req_str: "req_str-" <> _,
+             opt_str: nil,
+             req_int: 777,
+             opt_int: 123
+           } =
+             params =
+             Post
+             |> Ash.ActionInput.for_action(
+               :random_params,
+               %{
+                 action: :update
+               }
+             )
+             |> Ash.run_action!()
 
-    refute params |> Map.has_key?(:author)
+    refute Map.has_key?(params, :author)
+    refute Map.has_key?(params, :author_id)
   end
 
   describe "options" do