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有类似于以下示例的情况：

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

我需要在single roundtrip所有员工中检索他们的地址和电话已初始化，并且还cache the query需要在 2 级缓存中使用Cacheable().

使用：

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

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

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

应该工作，但我得到以下异常：

NHibernate.PropertyAccessException

信息：

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

信息：

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

如下查询不起作用，因为它会生成一个无效的笛卡尔积。有 1 名员工有 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。在服务器收到结果后使结果不同并不是一个好的选择。

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

仅使用FetchMany()and ToFuture()(no Cacheable()) 查询将在 1 次往返中正确返回具有相应地址和电话（无重复）的所有员工，但由于查询未缓存，因此不会对未来的相同请求进行优化：

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

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

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

TLDR：如何检索具有在单次往返中初始化的地址和电话的所有员工，并将查询缓存在 2 级缓存中？感谢您的回复！

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0 回答 0