Question

If I don’t map Color but map an object that has a Color attribute, FluentNHibernate successfully maps it to a varbinary(max). However, that’s extremely inefficient given that realistically Color is just composed of 4 bytes and I am keen on improving it without using a new type to Proxy it.

Internally within Color it is made up of four properties,

1. long value (cast down to int to represent ARGB)
2. short state, indicates if this is a known & valid colour
3. string name, the name of the colour if known.
4. short knownColor a value to indicate which known colour it is

So I have attempted to map this as follows.

public ColorMapping()
{
    CompositeId()
        .KeyProperty(c => Reveal.Member<Color, long>("value"))
        .KeyProperty(c => Reveal.Member<Color, short>("state"))
        .KeyProperty(c => Reveal.Member<Color, string>("name"))
        .KeyProperty(c => Reveal.Member<Color, short>("knownColor"));
}

However, on usage I get the following exception,

Class Initialization method DataContextTest.ClassInitialise threw
exception. FluentNHibernate.Cfg.FluentConfigurationException:
FluentNHibernate.Cfg.FluentConfigurationException: An invalid or
incomplete configuration was used while creating a SessionFactory.
Check PotentialReasons collection, and InnerException for more detail.

—> FluentNHibernate.Cfg.FluentConfigurationException: An invalid or
incomplete configuration was used while creating a SessionFactory.
Check PotentialReasons collection, and InnerException for more detail.

—> NHibernate.MappingException: Could not compile the mapping
document: (XmlDocument) —> NHibernate.MappingException: Could not
determine type for:
System.Linq.Expressions.Expression1[[System.Func2[[System.Drawing.Color,
System.Drawing, Version=4.0.0.0, Culture=neutral,
PublicKeyToken=b03f5f7f11d50a3a],[System.Int64, mscorlib,
Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]],
mscorlib, Version=4.0.0.0, Culture=neutral,
PublicKeyToken=b77a5c561934e089]], System.Core, Version=4.0.0.0,
Culture=neutral, PublicKeyToken=b77a5c561934e089, for columns:
NHibernate.Mapping.Column(Member).

Am I misusing Reveal? If so, how am I meant to use it?

Answer 1

i would map it as UserType which converts it back and forth

// in mapping
Map(x => x.Color).Column("ColorARGB").CustomType<ColorUserType>();

[Serializable]
class ColorUserType : IUserType
{
    public object Assemble(object cached, object owner)
    {
        return DeepCopy(cached);
    }

    public object DeepCopy(object value)
    {
        return value;
    }

    public object Disassemble(object value)
    {
        return DeepCopy(value);
    }

    bool IUserType.Equals(object x, object y)
    {
        var colorX = x as Color;
        var colorY = y as Color;
        return colorX == null ? colorY = null : colorX.ToArgb() == colorY.ToArgb();
    }

    public virtual int GetHashCode(object x)
    {
        var colorX = (Color)x;
        return (colorX != null) ? colorX.ToArgb() : 0;
    }

    public bool IsMutable { get { return false; } }

    public object NullSafeGet(IDataReader rs, string[] names, object owner)
    {
        return Color.FromArgb((int)NHibernateUtil.Int32.Get(rs, names[0]));
    }

    public void NullSafeSet(IDbCommand cmd, object value, int index)
    {
        NHibernateUtil.Int32.Set(cmd, ((Color)value).ToArgb(), index);
    }

    public object Replace(object original, object target, object owner)
    {
        return original;
    }

    public Type ReturnedType { get { return typeof(Color); } }

    public SqlType[] SqlTypes { get { return new []{ SqlTypeFactory.Int32 }; } }
}