Hi
In your case, the problem is neither NH's nor re-linq's, but the
Func<...> purposePredicate you're inserting into your query. This is
compiled code, not an IQueryable AST that can be converted to HQL.
Inside the IQueryable, it's a constant expression, and that's just
what the exception message says. (That said, it could be more specific
about the source of the problem.)
purposePredicate would need to be an Expression<...> too, but to get a
matching overload of any, Purposes would need to be of type
IQueryable<Purpose>.
You could try some subquery construct, or this should solve your
problem:
Expression<Func<Purpose, bool>> purposePredicate = p2 => p2.Id
== 1;
Expression<Func<Room, bool>> roomPredicate2 = r =>
r.Purposes.ToQueryable().Any(purposePredicate);
The ToQueryable method would be easy to build (casting explicitly
would be ugly), but re-linq would need to be aware of it (and probably
just ignore it).
Now if you want that, that would be a good time to switch to our list.
HTH,
Stefan
http://relinq.codeplex.com/
On May 5, 9:42 am, ulu <[email protected]> wrote:
> Howdy,
>
> I'm trying to construct a predicate and feed it into a LINQ query. My
> Room class has an ISet of Purpose objects, and I'm trying to find
> rooms with matching purposes. I started with the following:
> Expression<Func<Room, bool>> roomPredicate = r =>
> r.Purposes.Any(p
> => p.Id == 1);
> var results =
> session.Query<Room>().Where(roomPredicate).ToList();
> which executes correctly.
>
> But then I refactor the inner predicate into a separate variable (in
> order to construct it dynamically later):
> Func<Purpose, bool> purposePredicate = p => p.Id == 1;
> Expression<Func<Room, bool>> roomPredicate = r =>
> r.Purposes.Any(purposePredicate);
> var results =
> session.Query<Room>().Where(roomPredicate).ToList();
> it fails with the following exception:
> System.ArgumentException: Object of type
> 'System.Linq.Expressions.ConstantExpression' cannot be converted to
> type 'System.Linq.Expressions.LambdaExpression'.
>
> I'm not sure if this is a remotion problem or NH's. In the failing
> case, NH provides the following expression to remotion:
> value(NHibernate.Linq.NhQueryable`1[Domain.Room]).Where(r =>
> r.Purposes.Any(value(System.Func`2[Domain.Purpose,System.Boolean])))
>
> Do you think I should post this to the remotion mailing list?
>
> ulu
>
> Below is the stack trace:
>
> at System.RuntimeType.TryChangeType(Object value, Binder binder,
> CultureInfo culture, Boolean needsSpecialCast)
> at System.RuntimeType.CheckValue(Object value, Binder binder,
> CultureInfo culture, BindingFlags invokeAttr)
> at System.Reflection.MethodBase.CheckArguments(Object[] parameters,
> Binder binder, BindingFlags invokeAttr, CultureInfo culture, Signature
> sig)
> at
> Remotion.Data.Linq.Parsing.Structure.IntermediateModel.MethodCallExpressionNodeFactory.CreateExpressionNode(Type
> nodeType, MethodCallExpressionParseInfo parseInfo, Object[]
> additionalConstructorParameters)
> at
> Remotion.Data.Linq.Parsing.Structure.MethodCallExpressionParser.CreateExpressionNode(Type
> nodeType, MethodCallExpressionParseInfo parseInfo, Object[]
> additionalConstructorParameters)
> at
> Remotion.Data.Linq.Parsing.Structure.MethodCallExpressionParser.Parse(String
> associatedIdentifier, IExpressionNode source, IEnumerable`1 arguments,
> MethodCallExpression expressionToParse)
> at
> Remotion.Data.Linq.Parsing.Structure.ExpressionTreeParser.ParseMethodCallExpression(MethodCallExpression
> methodCallExpression, String associatedIdentifier)
> at
> Remotion.Data.Linq.Parsing.Structure.ExpressionTreeParser.ParseNode(Expression
> expression, String associatedIdentifier)
> at
> Remotion.Data.Linq.Parsing.Structure.ExpressionTreeParser.ParseTree(Expression
> expressionTree)
> at
> Remotion.Data.Linq.Parsing.Structure.QueryParser.GetParsedQuery(Expression
> expressionTreeRoot)
> at
> Remotion.Data.Linq.Parsing.ExpressionTreeVisitors.SubQueryFindingExpressionTreeVisitor.CreateSubQueryNode(MethodCallExpression
> methodCallExpression)
> at
> Remotion.Data.Linq.Parsing.ExpressionTreeVisitors.SubQueryFindingExpressionTreeVisitor.VisitExpression(Expression
> expression)
> at
> Remotion.Data.Linq.Parsing.ExpressionTreeVisitors.SubQueryFindingExpressionTreeVisitor.ReplaceSubQueries(Expression
> expressionTree, MethodCallExpressionNodeTypeRegistry nodeTypeRegistry)
> at
> Remotion.Data.Linq.Parsing.Structure.IntermediateModel.ExpressionResolver.GetResolvedExpression(Expression
> unresolvedExpression, ParameterExpression parameterToBeResolved,
> ClauseGenerationContext clauseGenerationContext)
> at
> Remotion.Data.Linq.Parsing.Structure.IntermediateModel.WhereExpressionNode.<>c__DisplayClass1.<GetResolvedPredicate>b__0(ExpressionResolver
> r)
> at
> Remotion.Data.Linq.Parsing.Structure.IntermediateModel.ResolvedExpressionCache`1.GetOrCreate(Func`2
> generator)
> at
> Remotion.Data.Linq.Parsing.Structure.IntermediateModel.WhereExpressionNode.GetResolvedPredicate(ClauseGenerationContext
> clauseGenerationContext)
> at
> Remotion.Data.Linq.Parsing.Structure.IntermediateModel.WhereExpressionNode.ApplyNodeSpecificSemantics(QueryModel
> queryModel, ClauseGenerationContext clauseGenerationContext)
> at
> Remotion.Data.Linq.Parsing.Structure.IntermediateModel.MethodCallExpressionNodeBase.Apply(QueryModel
> queryModel, ClauseGenerationContext clauseGenerationContext)
> at
> Remotion.Data.Linq.Parsing.Structure.QueryParser.ApplyAllNodes(IExpressionNode
> node, ClauseGenerationContext clauseGenerationContext)
> at
> Remotion.Data.Linq.Parsing.Structure.QueryParser.GetParsedQuery(Expression
> expressionTreeRoot)
> at NHibernate.Linq.NhRelinqQueryParser.Parse(Expression expression)
> in f:\Разные штуки\Visual Studio 2008\Projects\OpenSource\NHibernate
> \nhibernate\src\NHibernate\Linq\NhRelinqQueryParser.cs:line 58
> at NHibernate.Linq.NhLinqExpression.Translate(ISessionFactory
> sessionFactory) in f:\Разные штуки\Visual Studio 2008\Projects
> \OpenSource\NHibernate\nhibernate\src\NHibernate\Linq
> \NhLinqExpression.cs:line 64
> at
> NHibernate.Hql.Ast.ANTLR.ASTQueryTranslatorFactory.CreateQueryTranslators(String
> queryIdentifier, IQueryExpression queryExpression, String
> collectionRole, Boolean shallow, IDictionary`2 filters,
> ISessionFactoryImplementor factory) in f:\Разные штуки\Visual Studio
> 2008\Projects\OpenSource\NHibernate\nhibernate\src\NHibernate\Hql\Ast
> \ANTLR\ASTQueryTranslatorFactory.cs:line 27
> at
> NHibernate.Engine.Query.HQLExpressionQueryPlan.CreateTranslators(String
> expressionStr, IQueryExpression queryExpression, String
> collectionRole, Boolean shallow, IDictionary`2 enabledFilters,
> ISessionFactoryImplementor factory) in f:\Разные штуки\Visual Studio
> 2008\Projects\OpenSource\NHibernate\nhibernate\src\NHibernate\Engine
> \Query\HQLExpressionQueryPlan.cs:line 34
> at NHibernate.Engine.Query.HQLExpressionQueryPlan..ctor(String
> expressionStr, IQueryExpression queryExpression, String
> collectionRole, Boolean shallow, IDictionary`2 enabledFilters,
> ISessionFactoryImplementor factory) in f:\Разные штуки\Visual Studio
> 2008\Projects\OpenSource\NHibernate\nhibernate\src\NHibernate\Engine
> \Query\HQLExpressionQueryPlan.cs:line 23
> at NHibernate.Engine.Query.HQLExpressionQueryPlan..ctor(String
> expressionStr, IQueryExpression queryExpression, Boolean shallow,
> IDictionary`2 enabledFilters, ISessionFactoryImplementor factory) in f:
> \Разные штуки\Visual Studio 2008\Projects\OpenSource\NHibernate
> \nhibernate\src\NHibernate\Engine\Query\HQLExpressionQueryPlan.cs:line
> 17
> at
> NHibernate.Engine.Query.QueryPlanCache.GetHQLQueryPlan(IQueryExpression
> queryExpression, Boolean shallow, IDictionary`2 enabledFilters) in f:
> \Разные штуки\Visual Studio 2008\Projects\OpenSource\NHibernate
> \nhibernate\src\NHibernate\Engine\Query\QueryPlanCache.cs:line 88
> at
> NHibernate.Impl.AbstractSessionImpl.GetHQLQueryPlan(IQueryExpression
> queryExpression, Boolean shallow) in f:\Разные штуки\Visual Studio
> 2008\Projects\OpenSource\NHibernate\nhibernate\src\NHibernate\Impl
> \AbstractSessionImpl.cs:line 305
> at NHibernate.Impl.AbstractSessionImpl.CreateQuery(IQueryExpression
> queryExpression) in f:\Разные штуки\Visual Studio 2008\Projects
> \OpenSource\NHibernate\nhibernate\src\NHibernate\Impl
> \AbstractSessionImpl.cs:line 261
> at NHibernate.Linq.NhQueryProvider.Execute(Expression expression)
> in f:\Разные штуки\Visual Studio 2008\Projects\OpenSource\NHibernate
> \nhibernate\src\NHibernate\Linq\NhQueryProvider.cs:line 24
> at NHibernate.Linq.NhQueryProvider.Execute[TResult](Expression
> expression) in f:\Разные штуки\Visual Studio 2008\Projects\OpenSource
> \NHibernate\nhibernate\src\NHibernate\Linq\NhQueryProvider.cs:line 55
> at Remotion.Data.Linq.QueryableBase`1.GetEnumerator()
> at System.Collections.Generic.List`1..ctor(IEnumerable`1
> collection)
> at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
> at ZTests.PredicateTest.CanUseAPredicateInLinqQueries() in F:
> \Разные штуки\Visual Studio 2008\Projects\RentASpace\ZTests
> \PredicateTest.cs:line 30
>
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