create Group.js

+import { prisma } from "../../utils";
+
+export default {
+  Group: {
+    participants: (parent) =>
+      prisma.group.findOne({ where: { id: parent.id } }).participants(),
+    messages: (parent) =>
+      prisma.message.findOne({ where: { id: parent.id } }).messages(),
+  },
+};