improvement: support manual relationships (#66)

lib/graphql/dataloader.ex

@@ -235,6 +235,10 @@ defmodule AshGraphql.Dataloader do
 
         cardinality = relationship.cardinality
 
+        loads =
+          if Map.has_key?(relationship, :manual) && relationship.manual do
+            field
+          else
             query =
               query
               |> Ash.Query.new()
@@ -245,7 +249,10 @@ defmodule AshGraphql.Dataloader do
                 opts[:args]
               )
 
-        loaded = source.api.load!(records, [{field, query}], api_opts || [])
+            {field, query}
+          end
+
+        loaded = source.api.load!(records, [loads], api_opts || [])
 
         loaded =
           case loaded do

test/read_test.exs

@@ -613,4 +613,57 @@ defmodule AshGraphql.ReadTest do
                variables: %{"id" => post.id}
              )
   end
+
+  test "manual relationships can be read" do
+    tag =
+      AshGraphql.Test.Tag
+      |> Ash.Changeset.for_create(
+        :create,
+        name: "My Tag"
+      )
+      |> AshGraphql.Test.Api.create!()
+
+    post_1 =
+      AshGraphql.Test.Post
+      |> Ash.Changeset.for_create(:create, text: "foo", published: true)
+      |> Ash.Changeset.manage_relationship(
+        :tags,
+        [tag],
+        on_no_match: {:create, :create_action},
+        on_lookup: :relate
+      )
+      |> AshGraphql.Test.Api.create!()
+
+    AshGraphql.Test.Post
+    |> Ash.Changeset.for_create(:create, text: "bar", published: true)
+    |> Ash.Changeset.manage_relationship(
+      :tags,
+      [tag],
+      on_no_match: {:create, :create_action},
+      on_lookup: :relate
+    )
+    |> AshGraphql.Test.Api.create!()
+
+    doc = """
+    query ($id: ID!) {
+      getPost(id: $id) {
+        text
+        relatedPosts {
+          text
+        }
+      }
+    }
+    """
+
+    assert {:ok,
+            %{
+              data: %{
+                "getPost" => %{
+                  "relatedPosts" => [%{"text" => "bar"}],
+                  "text" => "foo"
+                }
+              }
+            }} ==
+             Absinthe.run(doc, AshGraphql.Test.Schema, variables: %{"id" => post_1.id})
+  end
 end

test/support/resources/post.ex

@@ -58,6 +58,35 @@ defmodule AfterActionRaiseResourceError do
   end
 end
 
+defmodule RelatedPosts do
+  @moduledoc false
+  use Ash.Resource.ManualRelationship
+  require Ash.Query
+
+  def load(posts, _opts, %{api: api}) do
+    posts = api.load!(posts, :tags)
+
+    {
+      :ok,
+      posts
+      |> Enum.map(fn post ->
+        tag_ids =
+          post.tags
+          |> Enum.map(& &1.id)
+
+        other_posts =
+          AshGraphql.Test.Post
+          |> Ash.Query.filter(tags.id in ^tag_ids)
+          |> Ash.Query.filter(id != ^post.id)
+          |> api.read!()
+
+        {post.id, other_posts}
+      end)
+      |> Map.new()
+    }
+  end
+end
+
 defmodule AshGraphql.Test.Post do
   @moduledoc false
 
@@ -317,5 +346,9 @@ defmodule AshGraphql.Test.Post do
       source_attribute_on_join_resource: :post_id,
       destination_attribute_on_join_resource: :tag_id
     )
+
+    has_many :related_posts, AshGraphql.Test.Post do
+      manual(RelatedPosts)
+    end
   end
 end