Delegate `System.Func' does not take `1' arguments

Question

when user enter password from login activity sending it to login service and waiting for the boolean response in login service.but its giving above syntax error(I mentioned it in code ) can any one solve my problem. i've to wait until the service response comes to my login activity

1.Login Interface

using System;
using System.Collections.Generic;
using System.Threading.Tasks;
namespace RetailAppShared
{
    public interface ILoginServices
    {
        bool AuthenticateUser (string passcode, Func<bool> function);
    }
}

2.Login service

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Net;
using RestSharp;
using System.Threading.Tasks;
using Newtonsoft.Json;

namespace RetailAppShared
{
    public class LoginServices : ILoginServices
    {               
        public bool AuthenticateUser (string passcode, Func<bool> function)
        {

            try {
                RestClient _client = new RestClient ("https://www.example.com/app/class");
                var request = new RestRequest ("loginservice", Method.POST) {
                    RequestFormat = DataFormat.Json
                };
                var obj = new login ();
                obj.passcode = passcode;

                request.AddJsonBody (obj);
                request.AddHeader ("Content-type", "application/json");
                _client.ExecuteAsync (request, response => {
                    if (response.StatusCode == HttpStatusCode.OK) {
                        if (!string.IsNullOrEmpty (response.Content)) {
                            var objlog = JsonConvert.DeserializeObject<LoginModel> (response.Content);
                            flag = objlog.result.state == 1 ? true : false;

                            function (true);//error
                        } else
                            flag = false;                            
                    }

                });
            } catch (Exception ex) {
                Debug.WriteLine (@" ERROR {0}", ex.Message);
            }               
        }    

    }

    class login
    {
        public string passcode { get; set; }    
    }
}

3.login activity

Login.Click += async (object sender, EventArgs e) => {

    progress = ProgressDialog.Show (this, "", "Connecting...");

    var isLoginSuccessful = loginAuthenticator.AuthenticateUser                
    (password.Text, (value) => {
        Console.WriteLine (value);
    });//error

    if (progress != null) {
        progress.Dismiss ();
        progress = null;
    }

    if (isLoginSuccessful) {                
        StartActivity (typeof(Ledger_HomeActivity));
        this.Finish ();
    } else {
       Toast.MakeText (this, "Invalid Login credentials! try    again", ToastLength.Short).Show ();
    }
};

A `Func` is like a method that returns a `bool` but has no parameters. You should call it like `bool result = function();`. If instead you want to pass a `bool` in and have no return values then you should use `Action` instead. — juharr, Jul 08 '16 at 11:33

score 4 · Answer 1 · answered Jul 08 '16 at 11:35

It looks like function represents a callback method that you call with the value of true or false, and that does not return any value back to you. In this case you should Action<bool> instead of Func<bool>, because Func<bool> does the opposite - it takes no parameters, and returns a bool value back to you.

score 2 · Accepted Answer · answered Jul 08 '16 at 11:35

The error appears at this line

var isLoginSuccessful = loginAuthenticator.AuthenticateUser (password.Text, (value) => { Console.WriteLine (value); }):

A Func<bool> returns a boolean without expecting anything. What you want instead is an Action<bool> that expects a boolean but returns void:

public bool AuthenticateUser (string passcode, Action<bool> function)
{
    function(true);
}

Delegate `System.Func' does not take `1' arguments

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