C＃，泛型，类型和NHibernate

Question

I'm learning the power of generics in C# in conjunction with NHibernate. I'd like to attempt the following in the pasted code.

In an attempt to do some post processing of N number of NHibernate objects I worked on a utility method leveraging generics to make it applicable to all NHibernate mapping classes we use now, or in the future. It works but I need to hard code each call for each mapping class. This is a pain and will need continuing updating as our schema and mappings change over time.

I do have an ever up-to-date list of all mapping classes by string name through the NHibernate mappings I generate on the fly. If there was a way to use this list of string names to call my generics based method, I'd be super happy.

Can anyone tell me if this is possible? Do I need to find another route?

Thanks so much in advance!!!

    public static void ProcessSomeItems()
    {
        // *************************************************************
        // As of now I have to list all classes as such to be processed
        // It works but I have to update manually when new mapping classes are created
        // *************************************************************
        NHibDoSomethingUtil<AspnetMembership>();
        NHibDoSomethingUtil<AspnetProfile>();
        NHibDoSomethingUtil<AspnetRole>();
        NHibDoSomethingUtil<AspnetUser>();
        // and so forth...


        // I have a up-to-date list of all mappings from "HbmMapping" and can get a list of all in the 
        // list form as below
        List<string> mappingNames = new List<string>();

        foreach (string mappingName in mappingNames)
        {
            Type theType = Type.GetType(mappingName);

            // I know I'm getting Types and Generics classes and so forth all jumbled but
            // how in the heck would I do something like the below?

            NHibDoSomethingUtil<theType>(); // Obviously doesn't compile ;-)
        }
    }

    // Generic method
    public static void NHibDoSomethingUtil<T>() where T : class
    {
        using (ISession session = sourceDBSessionFactory.OpenSession())
        {
            foreach (dynamic item in new List<T>(session.QueryOver<T>().List()))
            {
                // Process item;
            }
        }
    }

ecsousa gave great input and I was able to accomplish what I needed with something like the following.

        foreach (HbmClass mappingClass in mapping.Items)
        {
            Console.WriteLine(" -- Discovered Mapping: " + mappingClass.Name);

            Type mappingClassType = Type.GetType(mappingClass.Name);

            var genericMethod = typeof(Migration).GetMethod("NHibDoSomethingUtil");
            var method = genericMethod.MakeGenericMethod(mappingClassType);

            method.Invoke(null, null);

        }

Answer 1

You will need to use Reflection in order to accomplish this. Instead of directly calling NHibDoSomethingUtil, try this:

var genericMethod = typeof(TheClassName).GetMethod("NHibDoSomethingUtil");
var method = genericMethod.MakeGenericMethod(theType);

method.Invoke(null, null);

Note that you have to replace TheClassName by the class containing both methods.

Keep in mind the this kind of code is slow, and you should use it very carefully.