It won't be about self (that bit is fine), it will be about when you try to print the value.
Firstly, you have print(self.d_name) inside a method get_all(). But since your code never actually calls get_all()....
Even if you did call it. site_request()calls self.nam.get(req). But QNetworkAccessManager.get() only initiates a GET request. It does not wait for it to complete and return. Only when finished signal is received and handle_request() is called does self.d_name = ... get executed. That happens asynchronously at a later time. So trying to access it immediately after calling site_request() is too early.