dynamic-component fluent automapping - fluent-nhibernate

Question

Does anyone know how can we automatically map dynamic components using Fluent Automapping in NHibernate?
I know that we can map normal classes as components, but couldn't figure out how to map dictionaries as dynamic-components using fluent automapping.
Thanks

Answer 1

We've used the following approach successfully (with FluentNH 1.2.0.712):
public class SomeClass
{
public int Id { get; set; }
public IDictionary Properties { get; set; }
}
public class SomeClassMapping : ClassMap<SomeClass>
{
public SomeClassMapping()
{
Id(x => x.Id);
// Maps the MyEnum members to separate int columns.
DynamicComponent(x => x.Properties,
c =>
{
foreach (var name in Enum.GetNames(typeof(MyEnum)))
c.Map<int>(name);
});
}
}
Here we've mapped all members of some Enum to separate columns where all of them are of type int. Right now I'm working on a scenario where we use different types for the dynamic columns which looks like this instead:
// ExtendedProperties contains custom objects with Name and Type members
foreach (var property in ExtendedProperties)
{
var prop = property;
part.Map(prop.Name).CustomType(prop.Type);
}
This also works very well.
What I'm still about to figure out is how to use References instead of Map for referencing other types that have their own mapping...
UPDATE:
The case with References is unfortunately more complicated, please refer to this Google Groups thread. In short:
// This won't work
foreach (var property in ExtendedProperties)
{
var prop = property;
part.Reference(dict => dict[part.Name]);
}
// This works but is not very dynamic
foreach (var property in ExtendedProperties)
{
var prop = property;
part.Reference<PropertyType>(dict => dict["MyProperty"]);
}
That's all for now.

Answer 2

I got struggle with exactly the same problem. With fluent nHibernate we cannot map this but on my own I somehow was able to solve this. My solution is to build lambda expression on the fly and the assign this into object. For instance, lets say that:
Let my copy part of the site that Oliver refer:
DynamicComponent(
x => x.Properties,
part =>
{
// Works
part.Map("Size").CustomType(typeof(string));
// Works
var keySize = "Size";
part.Map(keySize).CustomType(typeof(string));
// Does not work
part.Map(d => d[keySize]).CustomType(typeof(string));
// Works
part.References<Picture>(d => d["Picture"]);
// Does not work
var key = "Picture";
part.References<Picture>(d => d[key]);
});
And we have this problem that we need to hardcode "Picture" in mapping. But somehow after some research I created following solution:
var someExternalColumnNames = GetFromSomewhereDynamicColumns();
'x' is a DynamicComponent callback in fluent Nhibernate e.g. (DynamicColumns): DynamicComponent(a => a.DynamicColumns, x => (...content of method below...))
foreach(var x in someExternalColumnNames)
{
if (x.IsReferenceToPerson == true)
{
var param = Expression.Parameter(typeof(IDictionary), "paramFirst");
var key = Expression.Constant(x.Name);
var me = MemberExpression.Call(param, typeof(IDictionary).GetMethod("get_Item"), new[] { key });
var r = Expression.Lambda<Func<IDictionary, object>>(me, param);
m.References<Person>(r, x.Name);
}
else
{
m.Map(x.Name)
}
}
//
// Some class that we want to reference, just an example of Fluent Nhibernate mapping
public class PersonMap : ClassMap<Person>
{
public PersonMap()
{
Table("Person");
Id(x => x.PersonId, "PersonId");
Map(x => x.Name);
}
}
public class Person
{
public virtual Guid PersonId { get; set; }
public virtual string Name { get; set; }
public Person()
{ }
}
Maybe it would be helpful