Unable to resolve dependency with configuration file settings

Question

I am kind of new to the dependency injection resolver techniques topic. May I know how we can resolve dependency through configuration file section(s). Below are my classes and interface along with the config file.

I am sure that missing some portion of code/setting. Can you please help me with this.

public interface IUserAuthentication
{
    string Authenticate(string username, string password);
    string GetUserRole(string username);
}

public class CloudAppAuthetication : IUserAuthentication
{
    public string Authenticate(string username, string password)
    {
        //Jwt token based authentication logic should be there
        return "This Authenticate method executed from cloud class";
    }

    public string GetUserRole(string username)
    {
        //New logic to user management api call
        return "This GetUserRole method executed from cloud class";
    }
}

public class StandaloneAppAuthetication : IUserAuthentication
{
    public string Authenticate(string username, string password)
    {
        //current logic should be here
        return "This Authenticate method executed from standalone class";
    }

    public string GetUserRole(string username)
    {
        //current logic should be here
        return "This GetUserRole method executed from standalone class";
    }
}

Console application calling of interface method:

class Program
{
    static void Main(string[] args)
    {
        IUnityContainer container = new UnityContainer();
        container.LoadConfiguration("TestContainer");
        IUserAuthentication _userAuthentication = null;
        string validatedUser = _userAuthentication.Authenticate(
            "testuser@user.com", "testpassword");
        string validatedUserRole =
            _userAuthentication.GetUserRole("testuser@user.com");
    }
}

My App.config file of console application is:

<?xml version="1.0" encoding="utf-8"?>
  <configuration>
    <configSections>
       <section name="unity"
  type="Microsoft.Practices.Unity.Configuration.UnityConfigurationSection,
Microsoft.Practices.Unity.Configuration" />
    </configSections>
    <unity xmlns = "http://schemas.microsoft.com/practices/2010/unity" >
      < container name="TestContainer">
        <register
  type="UnityConfiguration_Testing.IUserAuthentication,UnityConfiguration_Testing"
  mapTo="UnityConfiguration_Testing.StandaloneAppAuthetication,UnityConfiguration_Testing"
        />
      </container>
    </unity>
  <startup>
    <supportedRuntime version = "v4.0" sku=".NETFramework,Version=v4.5" />
  </startup>
</configuration>

I am getting object reference not set to an instance of object error. Expecting that StandaloneAppAuthetication class method will get executed as per my configuration.

Where's the code to resolve an instance from the container? You have `IUserAuthentication _userAuthentication = null;` ... — qujck, Apr 03 '19 at 07:47
You probably want `var _userAuthentication = container.Resolve()` — qujck, Apr 03 '19 at 07:50
Thank you so much @qujck. You are absolutely correct. After making code change with your suggestion it worked like a charm. — Buddha, Apr 03 '19 at 08:00
@qujck, may I know how can we do the same with MVC and MVC web api applications?. — Buddha, Apr 03 '19 at 08:31

score 0 · Answer 1 · answered Apr 03 '19 at 08:03

As @qujck suggested I made code change as below which worked fine. Thanks qujck.

using Microsoft.Practices.Unity;
using Microsoft.Practices.Unity.Configuration;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace UnityConfiguration_Testing
{
    class Program
    {
        static void Main(string[] args)
        {
            IUnityContainer container = new UnityContainer();
            container.LoadConfiguration("TestContainer");
            var _userAuthentication = container.Resolve<IUserAuthentication>();
            string validatedUser = _userAuthentication.Authenticate("testuser@user.com", "testpassword");
            string validatedUserRole = _userAuthentication.GetUserRole("testuser@user.com");
        }
    }
}

Unable to resolve dependency with configuration file settings

1 Answers1