Hi,
I am having problems mapping an BITORAGGREGATE SQl Function to
Linq.NHibernate.
I am using NH 4.0.3 and the Oracle10Provider.
The (simplified) domain model looks like this:
public class Person {
public virtual int Id { get; set;}
public virtual string Name { get;set; }
}
public class AccessRight {
public virtual int Id { get; set;}
public virtual Person Person { get; set;}
public virtual EnumRights AssignedRights { get;set; }
}
EnumRights is a flags enum with Values Read,Write,Delete,...
Basically I want to write a query that gives me all AccessRights that are
assigned to a given person
(Note that in the non simplified version rights can also be inherited from
Usergroups that the user belongs to!).
To be able to use this query as a filter I must compact the resultset of
the subquery to a single EnumRights value
by bit-oring all AssignedRights that my subquery returns.
For that I have written the BitOrAggregate:
SELECT BITORAGGREGATE(x.AccessRights) FROM AccessRight x where x.PersonId =
7
which returns a single EnumRights value.
But I am not able to successfully map this function.
I wrote the C# Linq-Code:
public static EnumRights BitOrAggregate(this IQueryable<AccessRight>
input, Expression<Func<AccessRight, EnumRights >> getter)
{
...
}
The BaseHqlgenerator:
public class BitOrAggregateAccessRightFlags : BaseHqlGeneratorForMethod
{
public BitOrAggregateAccessRightFlags()
{
SupportedMethods = new[] {
ReflectionHelper.GetMethod(() =>
LinqExtension.BitOrAggregate(null,null))
};
}
public override HqlTreeNode BuildHql(MethodInfo method, Expression
targetObject,
System.Collections.ObjectModel.ReadOnlyCollection<Expression>
arguments, HqlTreeBuilder treeBuilder, IHqlExpressionVisitor visitor)
{
HqlExpression hqlExpression =
visitor.Visit(arguments[1]).AsExpression();
return treeBuilder.MethodCall("BITORAGGREGATE",
hqlExpression);
}
}
And I added the new generator to the linq registry.
public class ExtendedLinqToHqlGeneratorsRegistry :
DefaultLinqToHqlGeneratorsRegistry
{
public ExtendedLinqToHqlGeneratorsRegistry() : base()
{
RegisterGenerator(ReflectionHelper.GetMethod(() =>
LinqExtension.BitOrAggregate(null,null)),
new BitOrAggregateAccessRightFlags());
}
}
But it still enters the C# Linq implementation instead of emitting
BITORAGGREGATE.
I clearly must be doing something wrong.
Any ideas/obvious mistakes?
Thanks,
Peter
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