NHibernate 2.0

      NHibernate源于非常优秀的基于Java的Hibernate关系型持久化工具。可是从2007年11月26日发布的1.2.1GA版本不是很好的支持VS2008。今天负责NHibernate开发的Ayende Rahien发布了NHibernate 2.0.0 Alpha 1，我们可以从这里下载，相信不久正式版会更好，先下载尝鲜一下。

下载看看源代码，其中很多代码都是用VS2008写的。并附了两个例子。

下面列表列出了一些改进：

• Add join mapping element to map one class to several tables
• <union> tables and <union-subclass> inheritance strategy
• HQL functions 'current_timestamp', 'str' and 'locate' for PostgreSQL dialect
• VetoInterceptor - Cancel Calls to Delete, Update, Insert via the IInterceptor Interface
• Using constants in select clause of HQL
• Added [ Table per subclass, using a discriminator ] Support to Nhibernate
• Added support for paging in sub queries.
• Auto discovery of types in custom SQL queries
• Added OnPreLoad & OnPostLoad Lifecycle Events
• Added ThreadStaticSessionContext
• Added <on-delete> tag to <key>
• Added foreign-key="none" since the Parent have not-found="ignore". (not relevant to SQL Server)
• Added DetachedQuery
• ExecuteUpdate support for native SQL queries
• From Hibernate:
  • Ported Actions, Events and Listeners
  • Ported StatelessSession
  • Ported CacheMode
  • Ported Statistics
  • Ported QueryPlan
  • Ported ResultSetWrapper
  • Ported  Structured/Unstructured cache
  • Ported SchemaUpdate
  • Ported Hibernate.UserTypes
  • Ported Hibernate.Mapping
  • Ported Hibernate.Type
  • Ported EntityKey
  • Ported CollectionKey
  • Ported TypedValue
  • Ported SQLExceptionConverter
  • Ported Session Context
  • Ported CascadingAction

• Changed NHibernate.Expression namespace to NHibernate.Criterion
• Changed NHiberante.Property namespace to NHiberante.Properties
• No AutoFlush outside a transaction - Database transactions are never optional, all communication with a database has to occur inside a transaction, no matter if you read or write data.
• <nhibernate> section is ignored, using <hibernate-configuration> section (note that they have different XML formats)
• Configuration values are no longer prefixed by "hibernate.", if before you would specify "hibernate.dialect", now you specify just "dialect"
• IInterceptor changed to match the Hibernate 3.2 Interceptor - interface changed
• Will perform validation on all named queries at initialization time, and throw if any is not valid.
• NHibernate will return long for count(*) queries on SQL Server
• SaveOrUpdateCopy return a new instance of the entity without change the original.
• INamingStrategy interface changed
• NHibernate.Search - Moved Index/Store attributes to the Attributes namespace
• Changes to IType, IEntityPersister, IVersionType - of interest only to people who did crazy stuff with NHibernate.
• <formula> must contain parenthesis when needed
• IBatcher interface change

• Fixing bug with HQL queries on map with formula.
• Fixed exception when the <idbag> has a <composite-element> inside; inside which, has a <many-to-one>
• Multi criteria doesn't support paging on dialects that doesn't support limiting the query size using SQL.
• Fixed an issue with limit string in MsSql2005 dialect sorting incorrectly on machines with multiple processors
• Fixed an issue with getting NullReferenceException when using SimpleSubqueryExpression within another subexpression
• Fixed Null Reference Exception when deleting a <list> that has holes in it.
• Fixed duplicate column name on complex joins of similar tables
• Fixed MultiQuery force to use parameter in all queries
• Fixed concat function fails when a parameter contains a comma, and using MaxResults
• Fixed failure with Formula when using the paging on MSSQL 2005 dialect
• Fixed PersistentEnumType incorrectly assumes enum types have zero-value defined
• Fixed SetMaxResults() returns one less row when SetFirstResult() is not used
• Fixed Bug in GetLimitString for SQL Server 2005 when ordering by aggregates
• Fixed SessionImpl.EnableFilter returns wrong filter if already enabled
• Fixed Generated Id does not work for MySQL
• Fixed one-to-one can never be lazy
• Fixed FOR UPDATE statements not generated for pessimistic locking

• Added Guid support for Postgre Dialect
• Added support for comments in queries
• Added Merge and Persist to ISession
• Support IFF for SQL Server
• IdBag now work with Identity columns
• Multi Criteria now uses the Result Transformer
• Handling key-many-to-one && not-found
• Can now specify that a class is abstract in the mapping.

• Prefer to use the Restrictions instead of the Expression class for defining Criteria queries.

• Added NHibernate.Validator
• Added NHibernate.Shards
• NHibernate.Search updated match to Hibernate Search 3.0

• Allow Inspection, Traversal, Cloning and Transformation for ICriteria and DetachedCriteria
  • Introduced CriteriaTransformer class
  • GetCriteriaByPath, GetCriteriaByAlias
• Added DetachedCriteria.For<T>
• Added Multi Criteria
• Projections can now pass parameters to the generated SQL statement.
• Added support for calling Sql Functions (HQL concept) from projections (Criteria).
• Added ConstantProjection
• Added CastProjection
• Can use IProjection as a parameter to ICriterion

• Now supports checking for internal fields as well
• Updated Castle.DynamicProxy2.dll to have better support for .NET 2.0 SP1

• Support for multi query and multi criteria
• Supporting subselects and limits
• Allowed DROP TABLE IF EXISTS semantics

• Enable Multi Query support for PostgreSQL

• Much better overall support

• Changed logging to make it clearer that all commands are send to the database in a single batch.
• AbstractBatcher now use the Interceptor to allow the user intercept and change an SQL before it's preparation

• Better error message on exception in getting values in Int32Type
• Better error message when using a subquery that contains a reference to non existing property
• Throws a more meaningful exception when calling UniqueResult<T>() with a value type and the query returns null.
• Overall better error handling
• Better debug logs

• Major refactoring internally to use generic collections instead of the non generic types.
• Major refactoring to the configuration and the parsing of hbm files.

• Added ProxyFactoryFactory
• Added BatchingBatcherFactory

作者：李永京（YJingLee's Blog）
出处：http://lyj.cnblogs.com
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