What does WebActivator do?

Question

This code was generated for me after added entity framework code-first for SQL Server CE using NuGet. They did no changes to any other file. The file SQLCEEntityFramework.cs was created and placed in App_Start folder.

Does this mean it automatically gets executed or something? The same thing happened when I added Ninject for MVC 3. No code was added to the global.ascx file so I have no idea if its plug and play or I have to configure something.

[assembly: WebActivator.PreApplicationStartMethod(typeof(StackTorrents.WebUI.App_Start.SQLCEEntityFramework), "Start")]

Sampler

This link : (Define an initialization order of WebActivator.PreApplicationStartMethod classes) may help whom the order of execution is important for them. – Heelpost

Answer 1

According to:

http://haacked.com/archive/2010/05/16/three-hidden-extensibility-gems-in-asp-net-4.aspx

This new attribute allows you to have code run way early in the ASP.NET pipeline as an application starts up. I mean way early, even before Application_Start. This happens to also be before code in your App_code folder (assuming you have any code in there) has been compiled. To use this attribute, create a class library and add this attribute as an assembly level attribute. A common place to add this would be in the AssemblyInfo.cs class within the Properties folder.

Facelift

The PreApplicationStartMethodAttribute from the .NET framework allows only one per assembly. Most importantly, WebActivator provides it's own implementation of the attribute that permits multiple instances of per assembly. – Depriest

@Ed Chapel - does this mean that when I imported SQLCE4 from nuget and also ninject, both has a PreApplicationStartMethod. Only a random one will be executed? – Sampler

I don't know about SQLCE4, but ninject uses WebActivator. I am certain that if you stick to the WebActivator attribute that all of the PreApplicationStartMethod attributes will run. – Depriest

I'm glad I found this. You can not search for Stack Overflow Exceptions in google any more. – Meggy

Answer 2

To clarify, it gives you a way of hooking into several application start and application shutdown events WITHOUT having to change any existing code files (previously you had to edit Globals.asax.cs).

This is mostly a big deal when making packages as these events are really useful for bootstrapping Http modules and it is really difficult to write code into existing files.

Deteriorate