Initialize Class with Parameter from Session-CodePudding

I am trying to figure out how (if it is even possible), to initialize a class once in a controller with parameter so that I don't have to create an instance in each method. I am getting back a bearer token that I need to submit with each call. This works:

    public string token
    {
        get { return (HttpContext.Session["AccessToken"] != null) ? HttpContext.Session["AccessToken"].ToString() : ""; }
        set { HttpContext.Session["AccessToken"] = value; }
    }

    public async Task<ActionResult> Index()
    {
        Client client = new Client();
        string token = await client.GetToken("TFBiUWxBU2trZnh;lkjlkj;lTZXRIfFN5ZWR8NjcwNzg=");
        Session["AccessToken"] = token;
        return View();
    }

    public async Task<ActionResult> About()
    {
        Client client = new Client(token);
        var employees = await client.GetEmployees();

        return View();
    }

I get the token and save it in a session variable then use it to create a new Client(token). What I am trying to find out if there is a way to create something like this:

        public Client _client = new Client(token);

at the top of the controller so that I don't have to keep creating a new instance in every method. I tried doing the following:

    public string token
    {
        get { return (HttpContext.Session["AccessToken"] != null) ? HttpContext.Session["AccessToken"].ToString() : ""; }
        set { HttpContext.Session["AccessToken"] = value; }
    }
    Client Client;
    public HomeController()
    {
        Client = new Client(token);
    }

but then the Session throws a System.NullReference.Exception. It seems there should be a way to do this, but I can't figure it out.

CodePudding user response：

Your HttpContext.Session isn't initialized by the time the constructor runs. It seems like you're actually looking for a get-only property though.

public Client _client => new Client(token);
// This is shorthand for the following
public Client _client { get { return new Client(token); } }

If you truly only want one, persistent instance, then you'll have to only create the client once the session has been initialized.