In a web application the domain classes and the validations associated with those classes forms the Model. Validation plays a core part in a Model. In ASP.NET MVC, model validations are done by using Data Annotations. Data Annotations are nothing but special attributes that are applied to a class or properties of a class. In many cases these built-in validation attributes are not sufficient to fulfill our business requirements and in those cases we can go for building our own custom validations.

In this article we will see how to apply basic validations to a model and also we will see how to create custom validations by implementing the ValidationAttribute class or IValidatableObject interface.

I wrote my first blog post about achieving dependency injection using Ninject right here, there we have discussed about some basic stuff and even tried a small sample. One of the nice things about Ninject is there are different extensions available along with the core assemblies to work with different frameworks. Ninject has extension to work with ASP.NET MVC framework as well. Along with the core assemblies we need to add assemblies Ninject.Web.Common and Ninject.Web.Mvc to use in MVC projects. Ninject.Web.Common is a common library for both web-forms and MVC. You can download the Ninject core and extensions from here.

We have two options to use Ninject MVC extensions in projects: one is adding the binaries directly to the projects and the other way is installing from NuGet Package Manager Console (Install-Package Ninject.MVC3). In this post we have used the first approach.

"Ninject is a lightweight dependency injection framework for .NET applications. It helps you split your application into a collection of loosely-coupled, highly-cohesive pieces, and then glue them back together in a flexible manner. By using Ninject to support your software's architecture, your code will become easier to write, reuse, test, and modify."

In this tutorial we are going to have a first look at using Ninject in .NET for dependency injection.