Handling OpenAccessContext in Web Projects

One of the most important things regarding Telerik Data Access based applications is the handling of the OpenAccessContext inside a web application.

The most important thing you should take care of is that the OpenAccessContext class implements the IDisposable interface. It is traditionally difficult to handle those cases in a web application, because of the stateless nature of the web. However, there are three highly efficient ways of dealing with this issue:

• Using a MasterPage - the MasterPage is common for all the pages in a web application. You can declare the OpenAccessContext as a member of the MasterPage and access it in all the pages code-behind methods. Read more
• Using the HttpContext - basically, you need to create a class that is responsible for getting and setting the OpenAccessContext from/to the HttpContext. Read more
• Creating a new instance of the context for each CRUD operation. Read more

In this tutorial you will use the second approach, i.e. handling the context using the HttpContext. Add a new class named ContextFactory in the CarRentWebSite project.

using System.Web;
using SofiaCarRental.Model;

namespace CarRentWebSite
{
    public class ContextFactory
    {
        private static readonly string contextKey = typeof( FluentModel ).FullName;

        public static FluentModel GetContextPerRequest()
        {
            HttpContext httpContext = HttpContext.Current;
            if ( httpContext == null )
            {
                return new FluentModel();
            }
            else
            {
                FluentModel context = httpContext.Items[contextKey] as FluentModel;

                if ( context == null )
                {
                    context = new FluentModel();
                    httpContext.Items[contextKey] = context;
                }

                return context;
            }
       }

        public static void Dispose()
        {
            HttpContext httpContext = HttpContext.Current;

            if ( httpContext != null )
            {
                FluentModel context = httpContext.Items[contextKey] as FluentModel;

                if ( context != null )
                {
                    context.Dispose();
                    httpContext.Items[contextKey] = null;
                }
            }
        }
    }
}

Imports SofiaCarRental.Model

Public Class ContextFactory
    Private Shared ReadOnly contextKey As String = GetType(FluentModel).FullName

    Public Shared Function GetContextPerRequest() As FluentModel
        Dim _httpContext As HttpContext = HttpContext.Current
        If _httpContext Is Nothing Then
            Return New FluentModel()
        Else
            Dim context As FluentModel = TryCast(_httpContext.Items(contextKey), FluentModel)

            If context Is Nothing Then
                context = New FluentModel()
                _httpContext.Items(contextKey) = context
            End If

            Return context
        End If
    End Function

    Public Shared Sub Dispose()
        Dim _httpContext As HttpContext = HttpContext.Current
        If _httpContext IsNot Nothing Then
            Dim context As FluentModel = TryCast(_httpContext.Items(contextKey), FluentModel)
            If context IsNot Nothing Then
                context.Dispose()
                _httpContext.Items(contextKey) = Nothing
            End If
        End If
    End Sub
End Class