How to implement CRUD features in ASP.NET Web API?

We are going to discuss how we can implement RESTful service layer using ASP.NET Web API.
In this program, we will use session object to persist as in-memory datastore.
Yes, REST is stateless. By using session, we will make it stateful. Well, the only purpose of using session in this program is to use some kind of back-end data store when we do CRUD actions. We are not using this type of data store in production code. We will use industry grade databases for that.
Alright, let's start hands-on work now. Open up Visual Studio 2015 and select File => New => Project and select "ASP.NET Web Application (.NET Framework)". Click "WebAPI" checkbox and create new project.
First we will create the Model class for Employee entity.

Model class

And make sure our WebApi return data in json format.

Configure to return JSON format

Here we will implement the API controller logic

Implement the RESTful API in the controller

In real-word application, we will have back-end database with ORM tool like Entity Framework. We will use dummy data for demo.

Generate the sample data in ActionFilter

For any WebApi, security is a very important factor. For simplicity sake, I just basic authentication to show-case the usage pattern.

For authenticating the routes

Add the entry for authentication in web.config file.
  <system.webServer>    <modules>      <add name="BasicAuthHttpModule" type="WebApiSampleProject.BasicAuthHttpModule, WebApiSampleProject" />    </modules>  </system.webServer>