c# DI Unity Container how to resolve dependent object

Question

We have following implementation of IProduct & ILogger class. Manager classes are being used as communication channel. We have used unity as given below to resolve manager class but it giving following error-

===================unity configuration==========

IUnityContainer container = new UnityContainer();
container.RegisterType<ILogger, FileLogger>("File");
container.RegisterType<ILogger, BDLogger>("DB");

container.RegisterType<IProduct, ProductA>("productA");
container.RegisterType<IProduct, ProductB>("productB");

container.RegisterType<ProducManager>(new InjectionConstructor(container.Resolve<IProduct>("productA")));

container.Resolve<ProducManager>("productA");

========================================================

"Resolution of the dependency failed, type = \"usingDI.IProduct\", name = \"productA\".\r\nException occurred while: while resolving.\r\nException is: InvalidOperationException - The current type, usingDI.ILogger, is an interface and cannot be constructed. Are you missing a type mapping?\r\n-----------------------------------------------\r\nAt the time of the exception, the container was:\r\n\r\n Resolving usingDI.ProductA,productA (mapped from usingDI.IProduct, productA)\r\n Resolving parameter \"logger\" of constructor usingDI.ProductA(usingDI.ILogger logger)\r\n Resolving usingDI.ILogger,(none)\r\n"}"

Please suggest me best way to resolve dependency for manager classes.

public interface IProduct
{
    void dosomething();
}

public class ProducManager
{
    IProduct _product;
    public ProducManager(IProduct product)
    {
        _product = product;
    }

    public void DoSomething()
    {
        _product.dosomething();
    }
}

public class ProductA : IProduct
{
    ILogger _logger;
    public ProductA(ILogger logger)
    {
        _logger = logger;
    }

    public void dosomething()
    {

        try
        {
            //code
            //
        }
        catch (Exception ex)
        {
            _logger.WriteLog(ex.Message);
        }
    }
}

public class ProductB : IProduct
{
    ILogger _logger;
    public ProductB(ILogger logger)
    {
        _logger = logger;
    }

    public void dosomething()
    {

        try
        {
            //code
            //
        }
        catch (Exception ex)
        {
            _logger.WriteLog(ex.Message);
        }
    }
}
public class LogManager
{
    ILogger _logger;
    public LogManager(ILogger logger)
    {
        _logger = logger;
    }

    public void WriteLog(string exception)
    {
        _logger.WriteLog(exception);
    }
}

public interface ILogger
{
    void WriteLog(string exception);
}

public class FileLogger : ILogger
{

    public void WriteLog(string exception)
    {

    }
}

public class BDLogger : ILogger
{

    public void WriteLog(string exception)
    {

    }
}

Answer 1

You need to register a type mapping for your interface ILogger. Otherwise does Unity not now which implementation of ILogger it should use (see your exception).

Here´s an example registering the interface ILogger with a mapping to FileLogger:

_container.RegisterType<ILogger, FileLogger>();

IProduct product = _container.Resolve<ProductA>(); //ILogger is injected to Product