NodeJS Nan C++ bind nested object to addon instance - c++

Question

In a C++ NodeJS project I'm currently working on, I want to have an object which contains a nested object, like
console.log(object.myObject); // { [keys: string]: any }
Without binding objects to properties my addon is working very well. I create the Instance with
auto ctor = Nan::New<v8::FunctionTemplate>(New);
auto ctorInst = ctor->InstanceTemplate();
And bind the object to the class instance like
v8::Local<v8::Object> obj = Nan::New<v8::Object>();
ctorInst->Set(Nan::New("myObject").ToLocalChecked(), obj);
which prints the following when executing the JS code (create an instance of the C++ extension).
# Fatal error in , line 0
# Check failed: !value_obj->IsJSReceiver() || value_obj->IsTemplateInfo().
On the other hand binding primitives (number, string, etc.) works flawlessly.
ctorInst->Set(Nan::New("myObject").ToLocalChecked(), Nan::New<v8::Number>(42));
Do you have got any suggestions? Thanks and cheers!

Answer 1

All templates (Including InstanceTemplate's) can only have other templates, or primitives, in them. As you see, IsTemplateInfo was false, when it should have been true. A similar question was asked and answered here. Simply make an ObjectTemplate and then populate it like you were doing with the FunctionTemplate.
Only when the Template is instantiated (with GetFunction), can you populate it with real objects.

Answer 2

In addition to Nicholas' answer I'd like to add the following.
Instance
Simply replace the v8::Object with v8::ObjectTemplate. Set properties to the object template and bind the template to the addon instance.
v8::Local<v8::ObjectTemplate> objTemplate = Nan::New<v8::ObjectTemplate>();
objTemplate->Set(Nan::New("prop").ToLocalChecked(), Nan::New<v8::Number>(42));
ctorInst->Set(Nan::New("myObject").ToLocalChecked(), objTemplate);
Now you are able to use
console.log(addonInstance.myObject); // { prop: 42 }
Prototype
If you want to bind functions to the object, create an object template like above. Then create a function template from an existing cpp function, and bind it to an object property of the object template. Then create a template on the addon instances prototype.
v8::Local<v8::ObjectTemplate> objTemplate = Nan::New<v8::ObjectTemplate>();
objTemplate->Set(Nan::New("prop").ToLocalChecked(), Nan::New<v8::Number>(42));
auto fn = Nan::New<v8::FunctionTemplate>(setup);
objTemplate->Set(Nan::New("setup").ToLocalChecked(), fn);
Nan::SetPrototypeTemplate(ctor, "myObj", objTemplate);
and the setup function is simply
NAN_METHOD(YourClass::setup) {
info.GetReturnValue().Set(Nan::New<v8::String>("Hello world").ToLocalChecked());
}
The console output would be
console.log(addonInstance.myObject) // { prop: 42, setup: [Function: setup] }