C# Unity InjectionFactory not working - c#-4.0

Question

I am using Unity as IOC and trying to inject an interface with a factory method which takes a interface as a parameter.
For some reason the configReader parameter in the factory method GetTitleParser(), is null and not getting the injected ConfigurationReader() instance.
When i place a debug point at the line in RegisterTypes method where the new InjectionFactory exists, ITitleParser is not showing as mapped to a proper mapped type.
can anyone help what am i doing wrong here?
Here is my code:
public class UnityContainerBuilder
{
public static IUnityContainer Build()
{
var container = new UnityContainer();
RegisterTypes(container);
return container;
}
public static void RegisterTypes(IUnityContainer container)
{
// NOTE: To load from web.config uncomment the line below. Make sure to add a Microsoft.Practices.Unity.Configuration to the using statements.
container.LoadConfiguration();
container.RegisterType<IConfigurationReader, ConfigurationReader>();
container.RegisterType<ITitleParser>(new InjectionFactory(c => ParserFactory.GetTitleParser()));
}
}
public class ParserFactory
{
public static ITitleParser GetTitleParser(IConfigurationReader configReader=null)
{
if(configReader==null) configReader = new ConfigurationReader();
/* rest of code here...*/
return parser;
}
}
It works when i use the following code. Is this the right way to do this?
container.RegisterType<IConfigurationReader, ConfigurationReader>();
container.RegisterType<ITitleParser>(new InjectionFactory(c =>
{
var configReader = c.Resolve<IConfigurationReader>();
var parser = ParserFactory.GetTitleParser(configReader);
return parser;
}));

Answer 1

When you use default parameters it's equal to:
container.RegisterType<ITitleParser>(
new InjectionFactory(c => ParserFactory.GetTitleParser(null)));
Because, compiler inserts all default values in method calls (null in your case).
So, your code is valid:
container.RegisterType<ITitleParser>(new InjectionFactory(c =>
{
var configReader = c.Resolve<IConfigurationReader>();
var parser = ParserFactory.GetTitleParser(configReader);
return parser;
}));
But i advice you to remove default value to make code more expressive.

Answer 2

Your code is valid but maybe you can avoid messing up with InjectionFactory parameters and ParserFactory.
public class UnityContainerBuilder
{
public static IUnityContainer Build()
{
var container = new UnityContainer();
RegisterTypes(container);
return container;
}
public static void RegisterTypes(IUnityContainer container)
{
// NOTE: To load from web.config uncomment the line below. Make sure to add a Microsoft.Practices.Unity.Configuration to the using statements.
container.LoadConfiguration();
container.RegisterType<IConfigurationReader, ConfigurationReader>();
container.RegisterInstance<IAppConfig>(container.Resolve<IConfigurationReader>().ReadConfiguration());
container.RegisterType<ITitleParser, TitleParser>();
}
}
public class AppConfig: IAppConfig
{
public AppConfig(){}
//value1 property
//value2 property
//etc
}
public class ConfigurationReader: IConfigurationReader
{
public ConfigurationReader(){}
public IAppConfig ReadConfiguration(){
var currentConfig = new AppConfig();
//read config from file, DB, etc and init currentCongif
return currentConfig;
}
}
public class TitleParser : ITitleParser
{
public TitleParser(IAppConfif)
{
//config already readed, just do the work
}
}