New class to enable NH session management in Web API

SharpLiteSrc/app/SharpLite.NHibernateProvider/WebApi/SessionPerRequestModule.cs

@@ -0,0 +1,101 @@
+using System;
+using System.Linq;
+using System.Web;
+using NHibernate;
+using System.Collections.Generic;
+
+// This is needed for the DependencyResolver...wish they would've just used Common Service Locator!
+using System.Net.Http;
+using System.Web.Http;
+using System.Web.Http.Controllers;
+using System.Web.Http.Dependencies;
+using System.Web.Http.Dispatcher;
+using System.Web.Http.Services;
+
+using System.Web.Mvc;
+
+
+namespace SharpLite.NHibernateProvider.WebApi
+{
+    /// <summary>
+    /// Taken from http://nhforge.org/blogs/nhibernate/archive/2011/03/03/effective-nhibernate-session-management-for-web-apps.aspx
+    /// </summary>
+    public class SessionPerRequestModule : IHttpModule
+    {
+        public void Init(HttpApplication context) {
+            context.BeginRequest += ContextBeginRequest;
+            context.EndRequest += ContextEndRequest;
+            context.Error += ContextError;
+        }
+
+        private void ContextBeginRequest(object sender, EventArgs e) {
+            foreach (var sessionFactory in GetSessionFactories()) {
+                var localFactory = sessionFactory;
+
+                LazySessionContext.Bind(new Lazy<ISession>(() => BeginSession(localFactory)), sessionFactory);
+            }
+        }
+
+        private static ISession BeginSession(ISessionFactory sessionFactory) {
+            var session = sessionFactory.OpenSession();
+            session.BeginTransaction();
+            return session;
+        }
+
+        private void ContextEndRequest(object sender, EventArgs e) {
+            foreach (var sessionfactory in GetSessionFactories()) {
+                var session = LazySessionContext.UnBind(sessionfactory);
+                if (session == null) continue;
+                EndSession(session);
+            }
+        }
+
+        private void ContextError(object sender, EventArgs e) {
+            foreach (var sessionfactory in GetSessionFactories()) {
+                var session = LazySessionContext.UnBind(sessionfactory);
+                if (session == null) continue;
+                EndSession(session, false);
+            }
+        }
+
+        private static void EndSession(ISession session, bool commitTransaction = true) {
+            try {
+                if (session.Transaction != null && session.Transaction.IsActive) {
+                    if (commitTransaction) {
+                        try {
+                            session.Transaction.Commit();
+                        }
+                        catch {
+                            session.Transaction.Rollback();
+                            throw;
+                        }
+                    }
+                    else {
+                        session.Transaction.Rollback();
+                    }
+                }
+            }
+            finally {
+                if (session.IsOpen)
+                    session.Close();
+
+                session.Dispose();
+            }
+        }
+
+        public void Dispose() { }
+
+        /// <summary>
+        /// Retrieves all ISessionFactory instances via IoC
+        /// </summary>
+        private IEnumerable<ISessionFactory> GetSessionFactories() {                        
+            var sessionFactories = GlobalConfiguration.Configuration.DependencyResolver
+                .GetServices(typeof(ISessionFactory)).Cast<ISessionFactory>();
+
+            if (sessionFactories == null || !sessionFactories.Any())
+                throw new TypeLoadException("At least one ISessionFactory has not been registered with IoC");
+
+            return sessionFactories;
+        }
+    }
+}