added better db migration support than what Subsonic provides out of the box.

Migrator.net/Migrator/MigrationLoader.cs

@@ -0,0 +1,136 @@
+using System;
+using System.Collections.Generic;
+using System.Reflection;
+using Migrator.Framework;
+
+namespace Migrator
+{
+    /// <summary>
+    /// Handles inspecting code to find all of the Migrations in assemblies and reading
+    /// other metadata such as the last revision, etc.
+    /// </summary>
+    public class MigrationLoader
+    {
+        private readonly ITransformationProvider _provider;
+        private readonly List<Type> _migrationsTypes = new List<Type>();
+
+        public MigrationLoader(ITransformationProvider provider, Assembly migrationAssembly, bool trace)
+        {
+            _provider = provider;
+            AddMigrations(migrationAssembly);
+
+            if (trace)
+            {
+                provider.Logger.Trace("Loaded migrations:");
+                foreach (Type t in _migrationsTypes)
+                {
+                    provider.Logger.Trace("{0} {1}", GetMigrationVersion(t).ToString().PadLeft(5), StringUtils.ToHumanName(t.Name));
+                }
+            }
+        }
+
+        public void AddMigrations(Assembly migrationAssembly)
+        {
+            if (migrationAssembly != null)
+                _migrationsTypes.AddRange(GetMigrationTypes(migrationAssembly));
+        }
+
+        /// <summary>
+        /// Returns registered migration <see cref="System.Type">types</see>.
+        /// </summary>
+        public List<Type> MigrationsTypes
+        {
+            get { return _migrationsTypes; }
+        }
+
+        /// <summary>
+        /// Returns the last version of the migrations.
+        /// </summary>
+        public long LastVersion
+        {
+            get
+            {
+                if (_migrationsTypes.Count == 0)
+                    return 0;
+                return GetMigrationVersion(_migrationsTypes[_migrationsTypes.Count - 1]);
+            }
+        }
+
+        /// <summary>
+        /// Check for duplicated version in migrations.
+        /// </summary>
+        /// <exception cref="CheckForDuplicatedVersion">CheckForDuplicatedVersion</exception>
+        public void CheckForDuplicatedVersion()
+        {
+            List<long> versions = new List<long>();
+            foreach (Type t in _migrationsTypes)
+            {
+                long version = GetMigrationVersion(t);
+
+                if (versions.Contains(version))
+                    throw new DuplicatedVersionException(version);
+
+                versions.Add(version);
+            }
+        }
+
+        /// <summary>
+        /// Collect migrations in one <c>Assembly</c>.
+        /// </summary>
+        /// <param name="asm">The <c>Assembly</c> to browse.</param>
+        /// <returns>The migrations collection</returns>
+        public static List<Type> GetMigrationTypes(Assembly asm)
+        {
+            List<Type> migrations = new List<Type>();
+            foreach (Type t in asm.GetExportedTypes())
+            {
+                MigrationAttribute attrib = 
+                    (MigrationAttribute)  Attribute.GetCustomAttribute(t, typeof (MigrationAttribute));
+
+                if (attrib != null && typeof(IMigration).IsAssignableFrom(t) && !attrib.Ignore)
+                {
+                    migrations.Add(t);
+                }
+            }
+
+            migrations.Sort(new MigrationTypeComparer(true));
+            return migrations;
+        }
+
+        /// <summary>
+        /// Returns the version of the migration
+        /// <see cref="MigrationAttribute">MigrationAttribute</see>.
+        /// </summary>
+        /// <param name="t">Migration type.</param>
+        /// <returns>Version number sepcified in the attribute</returns>
+        public static long GetMigrationVersion(Type t)
+        {
+            MigrationAttribute attrib = (MigrationAttribute)
+                                        Attribute.GetCustomAttribute(t, typeof(MigrationAttribute));
+
+            return attrib.Version;
+        }
+
+        public List<long> GetAvailableMigrations()
+        {
+        	//List<int> availableMigrations = new List<int>();
+            _migrationsTypes.Sort(new MigrationTypeComparer(true));
+            return _migrationsTypes.ConvertAll(new Converter<Type, long>(GetMigrationVersion));
+        }
+        
+        public IMigration GetMigration(long version)
+        {
+            foreach (Type t in _migrationsTypes)
+            {
+                if (GetMigrationVersion(t) == version)
+                {
+                    IMigration migration = (IMigration)Activator.CreateInstance(t);
+                    migration.Database = _provider;
+                    return migration;
+                }
+            }
+
+            return null;
+        }
+    }
+}