Nhibernate 3 Linq抛出Antlr.Runtime.NoViableAltException

如何解决Nhibernate 3 Linq抛出Antlr.Runtime.NoViableAltException

| 使用NHibernate 3 linq提供程序，我想选择子项的最大数量。 使用以下linq查询，我得到一个Antlr.Runtime.NoViableAltException，然后是一个Antlr.Runtime.MismatchedTreeNodeException

int maxCount = _repository.FindAll<Device>().Max(d=>d.DeviceSensors.Count());

存储库函数FindAll（）返回session.Query。 例外详情：

Antlr.Runtime.NoViableAltException occurred
  Message=\"Exception of type \'Antlr.Runtime.NoViableAltException\' was thrown.\"
  Source=\"NHibernate\"
  Char=0
  CharPositionInLine=-1
  Index=21
  Line=0
  UnexpectedType=84
  StackTrace:
       at NHibernate.Hql.Ast.ANTLR.HqlSqlWalker.aggregateExpr() in d:\\CSharp\\NH\\nhibernate\\src\\NHibernate\\Hql\\Ast\\ANTLR\\Generated\\HqlSqlWalker.cs:line 3203
  InnerException: 

。

Antlr.Runtime.MismatchedTreeNodeException occurred
  Message=\"Exception of type \'Antlr.Runtime.MismatchedTreeNodeException\' was thrown.\"
  Source=\"Antlr3.Runtime\"
  Char=0
  CharPositionInLine=-1
  Index=21
  Line=0
  UnexpectedType=84
  StackTrace:
       at Antlr.Runtime.Tree.TreeParser.RecoverFromMismatchedToken(IIntStream input,Int32 ttype,BitSet follow)
       at Antlr.Runtime.BaseRecognizer.Match(IIntStream input,BitSet follow)
       at NHibernate.Hql.Ast.ANTLR.HqlSqlWalker.functionCall() in d:\\CSharp\\NH\\nhibernate\\src\\NHibernate\\Hql\\Ast\\ANTLR\\Generated\\HqlSqlWalker.cs:line 7906
  InnerException:

 NHibernate.Hql.Ast.ANTLR.QuerySyntaxException: Exception of type \'Antlr.Runtime.NoViableAltException\' was thrown. [.First(.Select(.OrderByDescending(NHibernate.Linq.NhQueryable`1[RGB.TTT.Domain.Device],Quote((x,) => (x.DeviceSensors.Count)),),) => (new <>f__AnonymousType2`1(x.DeviceSensors.Count,))),)]

这是一个已知问题吗？还是我必须重写查询，欢迎提出任何建议。     

解决方法

显然，当前的NHibernate Linq提供程序无法在Select子句中组合Max（）和内部Select。您可能需要将“ Max”从“查询”中拉出，然后再应用它，例如

int maxCount = session.Query<Device>()
    .Select(d => d.DeviceSensors.Count)
    .ToList()
    .Max();

没有子选择的简单版本可以工作：

int maxCount = session.Query<Device>()
    .Select(d => d.Name.Length)
    .Max();