Pass arbitrary Javascript data object to Node.js C++ addon

user_1072039 0
Viewed 2903

I have a Node.js addon written in C++ using Nan. Works fantastically. However, I've not been able to figure out how to have my Node Javascript code pass an arbitrary data object (ex. {attr1:42, attr2:'hi', attr3:[5,4,3,2,1]}) to the C++ addon.

Until now, I've got around this by calling JSON.stringify() on my data object and then parsing the stringified JSON on the C++ side.

Ideally, I'd like to avoid copying data and just get a reference to the data object that I can access, or at least to copy it natively and avoid stringifying/parsing...

Any help would be appreciated!

node.js-nan node.js c++ json javascript
2 Answers

You can allow your Node.js c++ addons to take arbitrary typed arguments, but you must check and handle the types explicitly. He is a simple example function that shows how to do this:

void args(const Nan::FunctionCallbackInfo<v8::Value>& info) {

    int i = 0;
    while (i < info.Length()) {
        if (info[i]->IsBoolean()) {
            printf("boolean = %s", info[i]->BooleanValue() ? "true" : "false");
        } else if (info[i]->IsInt32()) {
            printf("int32 = %ld", info[i]->IntegerValue());
        } else if (info[i]->IsNumber()) {
            printf("number = %f", info[i]->NumberValue());
        } else if (info[i]->IsString()) {
            printf("string = %s", *v8::String::Utf8Value(info[i]->ToString()));
        } else if (info[i]->IsObject()) {
            printf("[object]");
            v8::Local<v8::Object> obj = info[i]->ToObject();
            v8::Local<v8::Array> props = obj->GetPropertyNames();
            for (unsigned int j = 0; j < props->Length(); j++) {
                printf("%s: %s",
                       *v8::String::Utf8Value(props->Get(j)->ToString()),
                       *v8::String::Utf8Value(obj->Get(props->Get(j))->ToString())
                      );
            }
        } else if (info[i]->IsUndefined()) {
            printf("[undefined]");
        } else if (info[i]->IsNull()) {
            printf("[null]");
        }
        i += 1;
    }
}

To actually solve the problem of handling arbitrary arguments that may contain objects with arbitrary data, I would recommend writing a function that parses an actual object similar to how I parsed function arguments in this example. Keep in mind that you may need to do this recursively if you want to be able to handle nested objects within the object.

user_55355500
Related