c++ - 将对象传递给 Node.js C++ 插件

Question

https://medium.com/@muehler.v/tutorial-to-node-js-native-c-modules-part-2-arrays-json-and-callbacks-9b81f09874cd

我正在阅读上面的文章，试图访问传递给 C++ Node 插件函数的对象中的字符串。我的功能在下面，但我无法将其编译成插件。当我这样做时，我得到了错误:

../addon.cpp:239:26: error: no viable conversion from 'MaybeLocal<v8::Value>' (aka 'v8::MaybeLocal<v8::Value>') to 'v8::Local<v8::Value>'
    v8::Local<v8::Value> pwdValue = Nan::Get(obj, pwdProp);
                         ^          ~~~~~~~~~~~~~~~~~~~~~~

关于如何解决此错误的任何想法？谢谢

NAN_METHOD(init) {
  v8::Local<v8::Object> obj = info[0]->ToObject();
  v8::Local<v8::String> pwdProp = Nan::New("PWD").ToLocalChecked();

  std::string pwd = "";

  if (Nan::HasOwnProperty(obj, pwdProp).FromJust()) {
    v8::Local<v8::Value> pwdValue = Nan::Get(obj, pwdProp);
    pwd = std::string(*Nan::Utf8String(pwdValue->ToString()));
  }

  std::cout << pwd << std::endl;
}

Answer 1

Nan::Get返回 MaybeLocal ，由于 docs 中提到的原因可能为空.

您可以获得Local来自 MaybeLocal 的句柄通过使用 .ToLocalChecked()如下:v8::Local<v8::Value> pwdValue = Nan::Get(obj, pwdProp).ToLocalChecked(); .

要检查 MaybeLocal 是否实际持有一个值，您可以检查 bool isEmpty = Nan::Get(obj, pwdProp).IsEmpty() .