In my quest for a version-wide database filter for an application, I have written the following code:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using FluentNHibernate.Automapping;
using FluentNHibernate.Automapping.Alterations;
using FluentNHibernate.Mapping;
using MvcExtensions.Model;
using NHibernate;
namespace MvcExtensions.Services.Impl.FluentNHibernate
{
public interface IVersionAware
{
string Version { get; set; }
}
public class VersionFilter : FilterDefinition
{
const string FILTERNAME = "MyVersionFilter";
const string COLUMNNAME = "Version";
public VersionFilter()
{
this.WithName(FILTERNAME)
.WithCondition("Version = :"+COLUMNNAME)
.AddParameter(COLUMNNAME, NHibernateUtil.String );
}
public static void EnableVersionFilter(ISession session,string version)
{
session.EnableFilter(FILTERNAME).SetParameter(COLUMNNAME, version);
}
public static void DisableVersionFilter(ISession session)
{
session.DisableFilter(FILTERNAME);
}
}
public class VersionAwareOverride : IAutoMappingOverride<IVersionAware>
{
#region IAutoMappingOverride<IVersionAware> Members
public void Override(AutoMapping<IVersionAware> mapping)
{
mapping.ApplyFilter<VersionFilter>();
}
#endregion
}
}
But, since overrides do not work on interfaces, I am looking for a way to implement this.
Currently I'm using this (rather cumbersome) way for each class that implements the interface :
public class SomeVersionedEntity : IModelId, IVersionAware
{
public virtual int Id { get; set; }
public virtual string Version { get; set; }
}
public class SomeVersionedEntityOverride : IAutoMappingOverride<SomeVersionedEntity>
{
#region IAutoMappingOverride<SomeVersionedEntity> Members
public void Override(AutoMapping<SomeVersionedEntity> mapping)
{
mapping.ApplyFilter<VersionFilter>();
}
#endregion
}
I have been looking at IClassmap interfaces etc, but they do not seem to provide a way to access the ApplyFilter method, so I have not got a clue here...
Since I am probably not the first one who has this problem, I am quite sure that it should be possible; I am just not quite sure how this works..
EDIT :
I have gotten a bit closer to a generic solution:
This is the way I tried to solve it :
Using a generic class to implement alterations to classes implementing an interface :
public abstract class AutomappingInterfaceAlteration<I> : IAutoMappingAlteration
{
public void Alter(AutoPersistenceModel model)
{
model.OverrideAll(map =>
{
var recordType =
map.GetType().GetGenericArguments().Single();
if (typeof(I).IsAssignableFrom(recordType))
{
this.GetType().GetMethod("overrideStuff").MakeGenericMethod(recordType).Invoke(this, new object[] { model });
}
});
}
public void overrideStuff<T>(AutoPersistenceModel pm) where T : I
{
pm.Override<T>( a => Override(a));
}
public abstract void Override<T>(AutoMapping<T> am) where T:I;
}
And a specific implementation :
public class VersionAwareAlteration : AutomappingInterfaceAlteration<IVersionAware>
{
public override void Override<T>(AutoMapping<T> am)
{
am.Map(x => x.Version).Column("VersionTest");
am.ApplyFilter<VersionFilter>();
}
}
Unfortunately I get the following error now :
[InvalidOperationException: Collection was modified; enumeration operation may not execute.]
System.ThrowHelper.ThrowInvalidOperationException(ExceptionResource resource) +51
System.Collections.Generic.Enumerator.MoveNextRare() +7661017
System.Collections.Generic.Enumerator.MoveNext() +61
System.Linq.WhereListIterator`1.MoveNext() +156
FluentNHibernate.Utils.CollectionExtensions.Each(IEnumerable`1 enumerable, Action`1 each) +239
FluentNHibernate.Automapping.AutoMapper.ApplyOverrides(Type classType, IList`1 mappedProperties, ClassMappingBase mapping) +345
FluentNHibernate.Automapping.AutoMapper.MergeMap(Type classType, ClassMappingBase mapping, IList`1 mappedProperties) +43
FluentNHibernate.Automapping.AutoMapper.Map(Type classType, List`1 types) +566
FluentNHibernate.Automapping.AutoPersistenceModel.AddMapping(Type type) +85
FluentNHibernate.Automapping.AutoPersistenceModel.CompileMappings() +746
EDIT 2 : I managed to get a bit further; I now invoke "Override" using reflection for each class that implements the interface :
public abstract class PersistenceOverride<I>
{
public void DoOverrides(AutoPersistenceModel model,IEnumerable<Type> Mytypes)
{
foreach(var t in Mytypes.Where(x=>typeof(I).IsAssignableFrom(x)))
ManualOverride(t,model);
}
private void ManualOverride(Type recordType,AutoPersistenceModel model)
{
var t_amt = typeof(AutoMapping<>).MakeGenericType(recordType);
var t_act = typeof(Action<>).MakeGenericType(t_amt);
var m = typeof(PersistenceOverride<I>)
.GetMethod("MyOverride")
.MakeGenericMethod(recordType)
.Invoke(this, null);
model.GetType().GetMethod("Override").MakeGenericMethod(recordType).Invoke(model, new object[] { m });
}
public abstract Action<AutoMapping<T>> MyOverride<T>() where T:I;
}
public class VersionAwareOverride : PersistenceOverride<IVersionAware>
{
public override Action<AutoMapping<T>> MyOverride<T>()
{
return am =>
{
am.Map(x => x.Version).Column(VersionFilter.COLUMNNAME);
am.ApplyFilter<VersionFilter>();
};
}
}
However, for one reason or another my generated hbm files do not contain any "filter" fields....
Maybe somebody could help me a bit further now ??
