Why is my static class not being initialized in ASP.NET MVC?

Question

I have a ASP.NET MVC project that has a static class in it to initialize some AutoMapper mappings:

static class AutoMappingConfiguration
{
    static AutoMappingConfiguration()
    {
        SetupMappings();
    }

    static void SetupMappings()
    {
        AutoMap.CreateMap<Product, ProductDTO>();
        // more mappings
    }
}

Setting a breakpoint in the static constructor shows me that it's never hit when I run the project. I have to explicitly call the method in MvcApplication.Application_Start():

AutoMappingConfiguration.SetupMappings();

Does anyone know why this static class is not being constructed by ASP.NET MVC? Does this have to do with the 'on-the-fly compilation' nature of IIS? If so, do I have to explicitly call the static method, or is there some way of configuring the project to initialize static classes?

Answer 1

I believe the code does get executed and you don't see it because you don't attach the debugger on time.

Verify this by having code that write to text file and see if the text file has been created:

static AutoMappingConfiguration()
{
    File.WriteAllText("C:\\mytestfile.txt", "AutoMappingConfiguration executed");
    SetupMappings();
}

Answer 2

Classes are initialised before the first time any of it's members are used. If you never use the class, the static constructor is never called.

Answer 3

The static constructor isn't called unless either an instance of the class is created or any static method is called, that's the documented/expected behavior. So you'll have to call that static method (or any other method in the class) to get it called.