Fix ArgumentError when a host LiveView uses stream/3 by dropping reserved assigns at every field-component spread site

lib/backpex/html/item_action.ex

@@ -36,7 +36,7 @@ defmodule Backpex.HTML.ItemAction do
           id={:item_action_modal}
           live_resource={@live_resource}
           action_type={:item}
-          {Map.drop(assigns, [:socket, :flash, :fields])}
+          {Map.drop(assigns, [:fields | Backpex.HTML.Resource.lv_reserved_assigns()])}
         />
       </div>
     </Layout.modal>

lib/backpex/html/resource.ex

@@ -17,6 +17,16 @@ defmodule Backpex.HTML.Resource do
 
   embed_templates("resource/*")
 
+  @doc """
+  Returns the list of assigns that `Phoenix.LiveView` reserves and that must be dropped
+  before spreading parent assigns into a child `Phoenix.LiveComponent`.
+
+  `Phoenix.Component.assign/3` rejects these keys with an `ArgumentError`. Centralizing
+  the list here ensures every spread site forwards the same safe subset of the parent's
+  assigns.
+  """
+  def lv_reserved_assigns, do: [:flash, :uploads, :streams, :socket, :myself]
+
   @doc """
   Renders a resource table.
   """
@@ -112,7 +122,7 @@ defmodule Backpex.HTML.Resource do
       id={"resource_#{@name}_#{@primary_key}"}
       module={@field_options.module}
       type={@type}
-      {Map.drop(assigns, [:socket, :flash, :myself, :uploads])}
+      {Map.drop(assigns, lv_reserved_assigns())}
     />
     """
   end
@@ -148,7 +158,7 @@ defmodule Backpex.HTML.Resource do
       id={@id}
       module={@field_options.module}
       type={@type}
-      {Map.drop(assigns, [:socket, :flash, :myself, :uploads])}
+      {Map.drop(assigns, lv_reserved_assigns())}
     />
     """
   end
@@ -183,7 +193,7 @@ defmodule Backpex.HTML.Resource do
       module={@field_options.module}
       lv_uploads={assigns[:uploads]}
       type={@type}
-      {Map.drop(assigns, [:socket, :flash, :myself, :uploads])}
+      {Map.drop(assigns, lv_reserved_assigns())}
     />
     """
   end

lib/backpex/html/resource/resource_form_main.html.heex

@@ -3,6 +3,6 @@
     module={Backpex.FormComponent}
     id={:edit}
     live_resource={@live_resource}
-    {Map.drop(assigns, [:socket, :flash])}
+    {Map.drop(assigns, lv_reserved_assigns())}
   />
 </.main_container>

lib/backpex/html/resource/resource_index.html.heex

@@ -12,7 +12,7 @@
       id={:modal}
       live_resource={@live_resource}
       action_type={:resource}
-      {Map.drop(assigns, [:socket, :flash, :fields])}
+      {Map.drop(assigns, [:fields | lv_reserved_assigns()])}
     />
   </.modal>
 

test/backpex/html/resource_test.exs

@@ -0,0 +1,24 @@
+defmodule Backpex.HTML.ResourceTest do
+  use ExUnit.Case, async: true
+
+  alias Backpex.HTML.Resource
+
+  describe "lv_reserved_assigns/0" do
+    test "includes every assign reserved by Phoenix.LiveView" do
+      reserved = Resource.lv_reserved_assigns()
+
+      for key <- [:flash, :uploads, :streams, :socket, :myself] do
+        assert key in reserved, "expected #{inspect(key)} in lv_reserved_assigns/0"
+      end
+    end
+
+    test "dropping the reserved set removes :streams from a parent-style assigns map" do
+      assigns = %{streams: %{example: :ref}, foo: 1, bar: 2}
+
+      result = Map.drop(assigns, Resource.lv_reserved_assigns())
+
+      refute Map.has_key?(result, :streams)
+      assert result == %{foo: 1, bar: 2}
+    end
+  end
+end