NHibernate OrderByDescending抛出异常`发生识别错误

Question

使用时:

.OrderByDescending(review => review.Country.Id == reviewCountryID)

SQL查询生成正确,不会引发错误.

使用时:

.OrderByDescending(review =>
    review.User != null &&
    review.User.Country != null &&
    review.User.Country.Id == userCountryID
)

抛出异常:

NHibernate.Hql.Ast.ANTLR.QuerySyntaxException
A recognition error occurred.

at NHibernate.Hql.Ast.ANTLR.ErrorCounter.ThrowQueryException()
at NHibernate.Hql.Ast.ANTLR.HqlSqlTranslator.Translate()
at NHibernate.Hql.Ast.ANTLR.QueryTranslatorImpl.DoCompile(IDictionary`2 replacements, Boolean shallow, String collectionRole)
at NHibernate.Hql.Ast.ANTLR.ASTQueryTranslatorFactory.CreateQueryTranslators(IASTNode ast, String queryIdentifier, String collectionRole, Boolean shallow, IDictionary`2 filters, ISessionFactoryImplementor factory)
at NHibernate.Engine.Query.QueryPlanCache.GetHQLQueryPlan(IQueryExpression queryExpression, Boolean shallow, IDictionary`2 enabledFilters)
at NHibernate.Impl.AbstractSessionImpl.GetHQLQueryPlan(IQueryExpression queryExpression, Boolean shallow)
at NHibernate.Impl.AbstractSessionImpl.CreateQuery(IQueryExpression queryExpression)
at NHibernate.Linq.DefaultQueryProvider.PrepareQuery(Expression expression, ref IQuery query, ref NhLinqExpression nhQuery)
at NHibernate.Linq.DefaultQueryProvider.Execute(Expression expression)
at NHibernate.Linq.DefaultQueryProvider.Execute(Expression expression)
at Remotion.Linq.QueryableBase`1.GetEnumerator()
at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
at System.Linq.Enumerable.ToList(IEnumerable`1 source)

有关如何解决此问题或替代方案的任何建议？

谢谢!

更新

更新了OrderBy以实际包含空检查.

在Select()表达式中投影review.User != null && review.User.Country != null && review.User.Country.Id == 144按预期工作,但OrderBy中的相同条件抛出异常.

更新

下面修复了多个连接的问题,但是在对它们执行布尔条件时却没有,这是问题所要求的:

使用投影属性执行OrderByDescending,然后仅投影实体查询,例如:

.Select(review => new
{
    Review = review,
    ReviewUserCountryId = (review.User != null && review.User.Country != null) ? review.User.Country.Id : (int?)null
})
.OrderByDescending(review => ReviewUserCountryId)
.Select(reviewInfo => reviewInfo.Review) // for aliasing assuming that ReviewUserCountryId won't be needed later in the query
// rest of query

Answer 1

似乎对于多个连接,NHibernate拒绝订购布尔值.

解决方案是对OrderBy中的整数进行排序,例如:

.OrderByDescending(review => (review.User != null && review.User.Country != null && review.User.Country.Id == userCountryID) ? 42 : -42);

如果有更好的解决方案,请添加它.