如何選擇他們的任何一個孩子都符合一組條件之一的父母名單？

我對使用LINQ的NHibernate查詢有問題，我想知道它是否在NHibernate中不受支持的用法？如何選擇他們的任何一個孩子都符合一組條件之一的父母名單？

我有一個父對象的列表，我想要一個所有這些父母的列表，當任何一個孩子符合一些標準。舉一個這樣的例子，想象一下，得到一個父母名單，其中有一個名叫John或Sarah的孩子。

這實際上是我試圖實現的，但我不斷收到錯誤。我所需要的和我編寫的LINQ查詢是完全合理的，但我不確定是否推動了NHibernate的LINQ實現的限制？基於以下意見

示例代碼

string[] names = {"John", "Sarah"}; 
session.Query().Where(parent => parent.Children 
        .Any(child => names.Contains(child.FirstName))) 
       .ToList();

建議，都給予同樣的錯誤IF名稱爲空。

string[] names = null; 
session.Query().Where(parent => names != null && parent.Children 
        .Any(child => names.Contains(child.FirstName))) 
       .ToList(); 

session.Query().Where(parent => parent.Children 
        .Any(child => names != null && names.Contains(child.FirstName))) 
       .ToList();

我不斷收到看起來像這樣的錯誤堆棧...

Value cannot be null. 
Parameter name: source 
    at System.Linq.Enumerable.Cast[TResult](IEnumerable source) 
    at NHibernate.Linq.Visitors.ResultOperatorProcessors.ProcessContains.IsEmptyList(HqlParameter source, VisitorParameters parameters) 
    at NHibernate.Linq.Visitors.ResultOperatorProcessors.ProcessContains.Process(ContainsResultOperator resultOperator, QueryModelVisitor queryModelVisitor, IntermediateHqlTree tree) 
    at NHibernate.Linq.Visitors.ResultOperatorProcessors.ResultOperatorProcessor`1.Process(ResultOperatorBase resultOperator, QueryModelVisitor queryModel, IntermediateHqlTree tree) 
    at NHibernate.Linq.Visitors.ResultOperatorProcessors.ResultOperatorMap.Process(ResultOperatorBase resultOperator, QueryModelVisitor queryModel, IntermediateHqlTree tree) 
    at NHibernate.Linq.Visitors.QueryModelVisitor.VisitResultOperator(ResultOperatorBase resultOperator, QueryModel queryModel, Int32 index) 
    at Remotion.Linq.Clauses.ResultOperatorBase.Accept(IQueryModelVisitor visitor, QueryModel queryModel, Int32 index) 
    at Remotion.Linq.QueryModelVisitorBase.VisitResultOperators(ObservableCollection`1 resultOperators, QueryModel queryModel) 
    at Remotion.Linq.QueryModelVisitorBase.VisitQueryModel(QueryModel queryModel) 
    at NHibernate.Linq.Visitors.QueryModelVisitor.Visit() 
    at NHibernate.Linq.Visitors.QueryModelVisitor.GenerateHqlQuery(QueryModel queryModel, VisitorParameters parameters, Boolean root) 
    at NHibernate.Linq.Visitors.HqlGeneratorExpressionTreeVisitor.VisitSubQueryExpression(SubQueryExpression expression) 
    at NHibernate.Linq.Visitors.HqlGeneratorExpressionTreeVisitor.VisitExpression(Expression expression) 
    at NHibernate.Linq.Visitors.HqlGeneratorExpressionTreeVisitor.Visit(Expression expression, VisitorParameters parameters) 
    at NHibernate.Linq.Visitors.QueryModelVisitor.VisitWhereClause(WhereClause whereClause, QueryModel queryModel, Int32 index) 
    at Remotion.Linq.Clauses.WhereClause.Accept(IQueryModelVisitor visitor, QueryModel queryModel, Int32 index) 
    at Remotion.Linq.QueryModelVisitorBase.VisitBodyClauses(ObservableCollection`1 bodyClauses, QueryModel queryModel) 
    at Remotion.Linq.QueryModelVisitorBase.VisitQueryModel(QueryModel queryModel) 
    at NHibernate.Linq.Visitors.QueryModelVisitor.Visit() 
    at NHibernate.Linq.Visitors.QueryModelVisitor.GenerateHqlQuery(QueryModel queryModel, VisitorParameters parameters, Boolean root) 
    at NHibernate.Linq.Visitors.HqlGeneratorExpressionTreeVisitor.VisitSubQueryExpression(SubQueryExpression expression) 
    at NHibernate.Linq.Visitors.HqlGeneratorExpressionTreeVisitor.VisitExpression(Expression expression) 
    at NHibernate.Linq.Visitors.HqlGeneratorExpressionTreeVisitor.Visit(Expression expression, VisitorParameters parameters) 
    at NHibernate.Linq.Visitors.QueryModelVisitor.VisitWhereClause(WhereClause whereClause, QueryModel queryModel, Int32 index) 
    at Remotion.Linq.Clauses.WhereClause.Accept(IQueryModelVisitor visitor, QueryModel queryModel, Int32 index) 
    at Remotion.Linq.QueryModelVisitorBase.VisitBodyClauses(ObservableCollection`1 bodyClauses, QueryModel queryModel) 
    at Remotion.Linq.QueryModelVisitorBase.VisitQueryModel(QueryModel queryModel) 
    at NHibernate.Linq.Visitors.QueryModelVisitor.Visit() 
    at NHibernate.Linq.Visitors.QueryModelVisitor.GenerateHqlQuery(QueryModel queryModel, VisitorParameters parameters, Boolean root) 
    at NHibernate.Linq.NhLinqExpression.Translate(ISessionFactoryImplementor sessionFactory) 
    at NHibernate.Hql.Ast.ANTLR.ASTQueryTranslatorFactory.CreateQueryTranslators(String queryIdentifier, IQueryExpression queryExpression, String collectionRole, Boolean shallow, IDictionary`2 filters, ISessionFactoryImplementor factory) 
    at NHibernate.Engine.Query.HQLExpressionQueryPlan.CreateTranslators(String expressionStr, IQueryExpression queryExpression, String collectionRole, Boolean shallow, IDictionary`2 enabledFilters, ISessionFactoryImplementor factory) 
    at NHibernate.Engine.Query.HQLExpressionQueryPlan..ctor(String expressionStr, IQueryExpression queryExpression, String collectionRole, Boolean shallow, IDictionary`2 enabledFilters, ISessionFactoryImplementor factory) 
    at NHibernate.Engine.Query.HQLExpressionQueryPlan..ctor(String expressionStr, IQueryExpression queryExpression, Boolean shallow, IDictionary`2 enabledFilters, 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, IQuery& query, NhLinqExpression& nhQuery) 
    at NHibernate.Linq.DefaultQueryProvider.Execute(Expression expression) 
    at NHibernate.Linq.DefaultQueryProvider.Execute[TResult](Expression expression) 
    at Remotion.Linq.QueryableBase`1.GetEnumerator() 
    at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection) 
    at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)

來源

2013-06-05 Nick Albrecht

難道那是parent.Children有時是空？ – Dominic

該查詢應該可以正常工作。在參數集合上調用IsEmptyList方法中唯一的Linq Cast方法調用，在你的情況下它是'names'。你確定'names'在你的情況下不是空的嗎？ – cremor

您是否嘗試將查詢的任何部分修改爲.Any（child => child！= null && names.Contains（child.FirstName）））。ToList（）; –