Merge conn[:graphql_options] with opts so that :graphql_options set in other plugs make it to GraphQL context.

lib/graphql/plug/endpoint.ex

@@ -55,7 +55,10 @@ defmodule GraphQL.Plug.Endpoint do
   end
 
   def call(%Conn{method: m} = conn, opts) when m in ["GET", "POST"] do
-    %{schema: schema, root_value: root_value} = conn.assigns[:graphql_options] || opts
+    if conn.assigns[:graphql_options] do
+      opts = Map.merge(opts, conn.assigns[:graphql_options])
+    end
+    %{schema: schema, root_value: root_value} = opts
 
     query = query(conn)
     variables = variables(conn)

test/graphql/plug/endpoint_test.exs

@@ -23,8 +23,9 @@ defmodule GraphQL.Plug.EndpointTest do
       }
     end
 
-    def greeting(_, %{name: name}, _), do: "Hello, #{name}!"
     def greeting(%{greeting: name}, _, _), do: "Hello, #{name}!"
+    def greeting(_, %{name: name}, _), do: "Hello, #{name}!"
+    def greeting(_, _, %{root_value: %{name: name}}), do: "Hello, #{name}!"
     def greeting(_, _, _), do: greeting(%{}, %{name: "world"}, %{})
   end
 
@@ -72,6 +73,26 @@ defmodule GraphQL.Plug.EndpointTest do
     assert_query TestRootPlugWithMF, {:get, "/", query: "{greeting}"}, {200, success}
   end
 
+  test "root data can be set in conn and made available in resolve context" do
+    defmodule TestRootPlugWithConn do
+      use Plug.Builder
+      defmodule ConnTest do
+        import Plug.Conn
+        def init(default), do: default
+
+        def call(conn, _default) do
+          assign(conn, :graphql_options, %{ root_value: %{ name: "Conn" } })
+        end
+      end
+
+      plug ConnTest
+      plug GraphQL.Plug.Endpoint, [schema: {TestSchema, :schema}]
+    end
+
+    success = ~S({"data":{"greeting":"Hello, Conn!"}})
+    assert_query TestRootPlugWithConn, {:get, "/", query: "{greeting}"}, {200, success}
+  end
+
   test "GET with variables" do
     success = ~S({"data":{"greeting":"Hello, Josh!"}})
     query = "query hi($name: String) { greeting(name: $name) }"