Update

backend/app/models/tutorial.model.js

@@ -0,0 +1,17 @@
+module.exports = mongoose => {
+  let schema = mongoose.Schema({
+      title: String,
+      description: String,
+      published: Boolean
+    },
+    { timestamps: true }
+  );
+
+  schema.method("toJSON", function() {
+    const { __v, _id, ...object } = this.toObject();
+    object.id = _id;
+    return object;
+  });
+
+  return mongoose.model("tutorial", schema);
+};