How to manage mongorepository singleton using unity - asp.net

Question

I want to use unity to manage my mongo repository but when I try registering it using the Web.config and LoadConfiguration() I get an error I am unable to decipher:
An exception of type 'System.ArgumentException' occurred in
Microsoft.Practices.Unity.Configuration.dll but was not handled in
user code
Additional information: The container named "" is not defined in this
configuration section.
This is my Global.asax
using System.Web;
using System.Web.Mvc;
using System.Web.Optimization;
using System.Web.Routing;
using Microsoft.Practices.Unity;
using Microsoft.Practices.Unity.Configuration;
namespace OOP_project
{
public class MvcApplication : System.Web.HttpApplication
{
internal static readonly IUnityContainer unity = new UnityContainer();
protected void Application_Start()
{
AreaRegistration.RegisterAllAreas();
FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
RouteConfig.RegisterRoutes(RouteTable.Routes);
BundleConfig.RegisterBundles(BundleTable.Bundles);
unity.LoadConfiguration();
}
}
}
and this is the relevant part of my Web.config
<configSections>
<!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 -->
<section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />
<section name="unity" type="Microsoft.Practices.Unity.Configuration.UnityConfigurationSection, Microsoft.Practices.Unity.Configuration"/>
</configSections>
<unity>
<typeAliases>
<typeAlias alias="string" type="System.String, mscorlib" />
</typeAliases>
<containers>
<container name="container">
<types>
<type type="MongoRepository.MongoRepository`1, MongoRepository" mapTo="MongoRepository.MongoRepository`1, MongoRepository">
<lifetime type="Singleton" />
<constructor>
<param name="connectionString" parameterType="string" value="mongodb://127.0.0.1/Blog"></param>
</constructor>
</type>
</types>
</container>
</containers>
</unity>
I would like to understand what this error actually means and how to fix it.

Answer 1

I see two problems with your code:
First, you need to specify the container name when you call LoadConfiguration. In the configuration file, the container name is "container" (in the <container> xml element), so you need to specify that like this:
unity.LoadConfiguration("container");
Or alternatively, change the container name in the configuration file to an empty string like this:
<container name="">
The second problem which is not directly related to your question is that the singleton lifetime should be specified with a small letter like this:
<lifetime type="singleton" />
By the way, why do you want to use a configuration file to configure Unity? Configuring Unity with a configuration file is brittle. For example, if you change a class name in code, it will not change in the configuration file. You would have to change it manually or your application would break.
Unless you need to be able to change dependencies without recompilation, your should prefer to configure the container via code.
Please note that you could make some of the registrations through code and some in the configuration file (for the dependencies that you need to be able to change without recompilation). You could easily find a resource online of how to do that.