Question

我正在创建并从一个从c ++节点插件调用的函数返回一个javascript函数对象。该对象已创建，但未被该函数返回。

回调函数，用于创建名为cursor的对象

var callback_fn = function(record){
    var res = new cursor(records);//functionalities of res(created here are working here when tested inside callback_fn but its not getting returned)
    return res;//not only object, nothing was getting returned.I even tried returning a dummy var.

}

调用“callback_fn”的节点插件片段（在args [1]中）

//Isolate* isolate = Isolate::GetCurrent();
//HandleScope scope(isolate);
Local<Object> obj= Object::New(isolate);
obj->Set(String::NewFromUtf8(isolate,"name"),Integer::New(isolate,custnum));
obj->Set(String::NewFromUtf8(isolate,"address"),Integer::New(isolate,custnum));//integer is assigned to name and address just for testing.
obj->Set(String::NewFromUtf8(isolate,"custnum"),Integer::New(isolate,custnum));
Local<Function> cb = Local<Function>::Cast(args[1]);
Local<Value> argv[1] = {obj};
cb->Call(isolate->GetCurrentContext()->Global(), 1, argv);

Answer 1

代码中的错误是javascript函数“callback_fn”将对象返回到cpp插件。因此，我们需要将它存储在cpp插件中并返回它，以便实现回调。

ret_val = cb->Call(isolate->GetCurrentContext()->Global(), 1, argv); 
//where ret_val is defined as Local<value> ret_val;
args.GetReturnValue().Set(ret_val);

在javscript中存储并返回。

var res_final=addon.addonfunction(input to addon);
return res_final;

如果写入的cpp插件不是异步的，我们可以在节点程序中将res存储一个单独的var，并在addon.addonfunction（输入到addon）完成执行后返回它（因为所有内容都按顺序执行同步程序）。

从一个从节点cpp addon调用的javascript函数返回一个js对象

1 个答案: