field via relationship with type, alias (nil wild)

lib/diffo/provider/components/calculations/field_via_relationship.ex

@@ -0,0 +1,34 @@
+# SPDX-FileCopyrightText: 2025 diffo contributors <https://github.com/diffo-dev/diffo/graphs.contributors>
+#
+# SPDX-License-Identifier: MIT
+
+defmodule Diffo.Provider.Calculations.FieldViaRelationship do
+  @moduledoc false
+  use Ash.Resource.Calculation
+
+  @impl true
+  def load(_query, _opts, _context), do: []
+
+  @impl true
+  def calculate(records, opts, _context) do
+    alias_name = opts[:alias]
+    type = opts[:type]
+    field = opts[:field]
+
+    Enum.map(records, fn record ->
+      filter = [source_id: record.id]
+      filter = if type, do: Keyword.put(filter, :type, type), else: filter
+      filter = if alias_name, do: Keyword.put(filter, :alias, alias_name), else: filter
+
+      Diffo.Provider.DefinedSimpleRelationship
+      |> Ash.Query.filter_input(filter)
+      |> Ash.read!(domain: Diffo.Provider)
+      |> Enum.flat_map(fn rel ->
+        Diffo.Provider.Instance
+        |> Ash.Query.filter_input(id: rel.target_id)
+        |> Ash.read!(domain: Diffo.Provider)
+        |> Enum.map(&Map.get(&1, field))
+      end)
+    end)
+  end
+end

test/provider/extension/field_via_aliased_relationship_test.exs → test/provider/extension/field_via_relationship_test.exs

@@ -2,7 +2,7 @@
 #
 # SPDX-License-Identifier: MIT
 
-defmodule Diffo.Provider.Extension.FieldViaAliasedRelationshipTest do
+defmodule Diffo.Provider.Extension.FieldViaRelationshipTest do
   @moduledoc false
   use ExUnit.Case, async: true
   @moduletag :domain_extended
@@ -15,7 +15,7 @@ defmodule Diffo.Provider.Extension.FieldViaAliasedRelationshipTest do
     on_exit(&AshNeo4j.Sandbox.rollback/0)
   end
 
-  describe "FieldViaAliasedRelationship — aliased" do
+  describe "FieldViaRelationship — aliased" do
     test "returns field from target instance reached via alias" do
       {:ok, shelf} = Parties.build_shelf_with_installer()
       {:ok, card} = Servo.build_card(%{name: "target-card"})
@@ -65,8 +65,8 @@ defmodule Diffo.Provider.Extension.FieldViaAliasedRelationshipTest do
     end
   end
 
-  describe "FieldViaAliasedRelationship — unaliased (all targets)" do
-    test "returns fields from all related target instances regardless of alias" do
+  describe "FieldViaRelationship — type filter" do
+    test "type filters to only relationships of the matching type" do
       {:ok, shelf} = Parties.build_shelf_with_installer()
       {:ok, card_a} = Servo.build_card(%{name: "target-a"})
       {:ok, card_b} = Servo.build_card(%{name: "target-b"})
@@ -79,23 +79,15 @@ defmodule Diffo.Provider.Extension.FieldViaAliasedRelationshipTest do
       })
 
       Diffo.Provider.create_defined_simple_relationship!(%{
-        type: :assignedTo,
-        alias: :other,
+        type: :reliesOn,
+        alias: :link,
         source_id: shelf.id,
         target_id: card_b.id
       })
 
-      shelf = Ash.load!(shelf, [:all_linked_names], domain: Servo)
-
-      assert Enum.sort(shelf.all_linked_names) == ["target-a", "target-b"]
-    end
-
-    test "returns empty list when no relationships exist" do
-      {:ok, shelf} = Parties.build_shelf_with_installer()
-
-      shelf = Ash.load!(shelf, [:all_linked_names], domain: Servo)
+      shelf = Ash.load!(shelf, [:assigned_linked_name], domain: Servo)
 
-      assert shelf.all_linked_names == []
+      assert shelf.assigned_linked_name == ["target-a"]
     end
   end
 end

test/support/resource/instance/shelf_instance.ex

@@ -86,10 +86,11 @@ defmodule Diffo.Test.Instance.ShelfInstance do
 
   calculations do
     calculate :linked_target_name, {:array, :string},
-      {Diffo.Provider.Calculations.FieldViaAliasedRelationship, [alias: :link, field: :name]}
+      {Diffo.Provider.Calculations.FieldViaRelationship, [alias: :link, field: :name]}
 
-    calculate :all_linked_names, {:array, :string},
-      {Diffo.Provider.Calculations.FieldViaAliasedRelationship, [field: :name]}
+    calculate :assigned_linked_name, {:array, :string},
+      {Diffo.Provider.Calculations.FieldViaRelationship,
+       [type: :assignedTo, alias: :link, field: :name]}
   end
 
   actions do