Question

具有类似于以下示例的情况：

包含2个子集合的1个父实体Employee：Addresses和Phones

我需要在single roundtrip所有员工中检索其初始化的地址和电话，并cache the query使用Cacheable()在2级缓存中实现这一点。

使用：

var baseQuery = session
    .Query<Employee>()
    .Cacheable();

baseQuery
    .FetchMany(e => e.Addresses)
    .ToFuture();

var list = baseQuery
    .FetchMany(e => e.Phones)
    .ToFuture()
    .ToList();

应该有效，但我得到以下异常：

NHibernate.PropertyAccessException

消息：

Exception occurred getter of NHibernateTest.Objects.Entity`1[[System.Int32, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]].Id

堆栈跟踪：

at NHibernate.Properties.BasicPropertyAccessor.BasicGetter.Get(Object target) in p:\nhibernate-core\src\NHibernate\Properties\BasicPropertyAccessor.cs:line 213
at NHibernate.Tuple.Entity.AbstractEntityTuplizer.GetIdentifier(Object entity) in p:\nhibernate-core\src\NHibernate\Tuple\Entity\AbstractEntityTuplizer.cs:line 139
at NHibernate.Persister.Entity.AbstractEntityPersister.GetIdentifier(Object obj, EntityMode entityMode) in p:\nhibernate-core\src\NHibernate\Persister\Entity\AbstractEntityPersister.cs:line 3890
at NHibernate.Persister.Entity.AbstractEntityPersister.IsTransient(Object entity, ISessionImplementor session) in p:\nhibernate-core\src\NHibernate\Persister\Entity\AbstractEntityPersister.cs:line 3676
at NHibernate.Engine.ForeignKeys.IsTransient(String entityName, Object entity, Nullable`1 assumed, ISessionImplementor session) in p:\nhibernate-core\src\NHibernate\Engine\ForeignKeys.cs:line 194
at NHibernate.Engine.ForeignKeys.GetEntityIdentifierIfNotUnsaved(String entityName, Object entity, ISessionImplementor session) in p:\nhibernate-core\src\NHibernate\Engine\ForeignKeys.cs:line 250
at NHibernate.Type.ManyToOneType.Disassemble(Object value, ISessionImplementor session, Object owner) in p:\nhibernate-core\src\NHibernate\Type\ManyToOneType.cs:line 137
at NHibernate.Impl.MultipleQueriesCacheAssembler.Disassemble(Object value, ISessionImplementor session, Object owner) in p:\nhibernate-core\src\NHibernate\Impl\MultipleQueriesCacheAssembler.cs:line 33
at NHibernate.Cache.StandardQueryCache.Put(QueryKey key, ICacheAssembler[] returnTypes, IList result, Boolean isNaturalKeyLookup, ISessionImplementor session) in p:\nhibernate-core\src\NHibernate\Cache\StandardQueryCache.cs:line 74
at NHibernate.Impl.MultiQueryImpl.ListUsingQueryCache() in p:\nhibernate-core\src\NHibernate\Impl\MultiQueryImpl.cs:line 749
at NHibernate.Impl.MultiQueryImpl.List() in p:\nhibernate-core\src\NHibernate\Impl\MultiQueryImpl.cs:line 415
at NHibernate.Impl.FutureQueryBatch.GetResultsFrom(IMultiQuery multiApproach) in p:\nhibernate-core\src\NHibernate\Impl\FutureQueryBatch.cs:line 24
at NHibernate.Impl.FutureBatch`2.GetResults() in p:\nhibernate-core\src\NHibernate\Impl\FutureBatch.cs:line 73
at NHibernate.Impl.FutureBatch`2.get_Results() in p:\nhibernate-core\src\NHibernate\Impl\FutureBatch.cs:line 31
at NHibernate.Impl.FutureBatch`2.GetCurrentResult[TResult](Int32 currentIndex) in p:\nhibernate-core\src\NHibernate\Impl\FutureBatch.cs:line 79
at NHibernate.Impl.FutureBatch`2.<>c__DisplayClass4`1.<GetEnumerator>b__3() in p:\nhibernate-core\src\NHibernate\Impl\FutureBatch.cs:line 63
at NHibernate.Impl.DelayedEnumerator`1.<get_Enumerable>d__0.MoveNext() in p:\nhibernate-core\src\NHibernate\Impl\DelayedEnumerator.cs:line 26
at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
at Tests.Tests.CacheableFetchManyAndToFutureTest() in D:\somepath\Tests.cs:line 262

内部异常：

System.Reflection.TargetException

消息：

Object does not match target type.

堆栈跟踪：

at System.Reflection.RuntimeMethodInfo.CheckConsistency(Object target)
at System.Reflection.RuntimeMethodInfo.InvokeArgumentsCheck(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
at System.Reflection.RuntimePropertyInfo.GetValue(Object obj, Object[] index)
at NHibernate.Properties.BasicPropertyAccessor.BasicGetter.Get(Object target) in p:\nhibernate-core\src\NHibernate\Properties\BasicPropertyAccessor.cs:line 207

查询以下内容不起作用，因为它生成笛卡尔积，结果无效。让1名员工拥有2个地址和2部电话，数据库中的每个唯一地址和电话将在地址和电话集合中出现两次。在服务器上收到结果后，结果不同是不太好的选择。

var list = session
    .Query<Employee>()
    .FetchMany(e => e.Addresses)
    .FetchMany(e => e.Phones)
    .Cacheable()
    .ToList();

仅使用FetchMany()和ToFuture()（无Cacheable()）查询将在1次往返中正确返回所有具有相应地址和电话（没有重复项）的员工，但由于查询不是缓存中没有针对未来相同请求的优化：

var baseQuery = session
    .Query<Employee>();

baseQuery
    .FetchMany(e => e.Addresses)
    .ToFuture();

var list = baseQuery
    .FetchMany(e => e.Phones)
    .ToFuture()
    .ToList();

TLDR：如何在单次往返中初始化地址和电话检索所有员工，并将查询缓存在二级缓存中？谢谢你的回复！

同一个NHibernate Linq查询中的Cacheable（），FetchMany（）和ToFuture（）

0 个答案: