Addressing issues in Oracle.DataAccess and AliasToBeanTransformer

OracleSQLAliasToBeanTransformer.cs

[Serializable]
public class OracleSQLAliasToBeanTransformer : IResultTransformer
{
	const BindingFlags Flags = BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance;
	readonly System.Type _resultClass;
	ISetter[] _setters;
	readonly IPropertyAccessor _propertyAccessor;
	readonly ConstructorInfo _constructor;
	readonly PropertyInfo[] _fields;
	public OracleSQLAliasToBeanTransformer(Type resultClass)
	{
		if (resultClass == null)
		{
			throw new ArgumentNullException("resultClass");
		}
		this._resultClass = resultClass;

		_constructor = resultClass.GetConstructor(Flags, null, Type.EmptyTypes, null);

		// if resultClass is a ValueType (struct), GetConstructor will return null... 
		// in that case, we'll use Activator.CreateInstance instead of the ConstructorInfo to create instances
		if (_constructor == null && resultClass.IsClass)
		{
			throw new ArgumentException("The target class of a AliasToBeanResultTransformer "
									   +"needs a parameter-less constructor.", "resultClass");
		}

		_propertyAccessor = new ChainedPropertyAccessor(new[]
		{
			PropertyAccessorFactory.GetPropertyAccessor(null),
			PropertyAccessorFactory.GetPropertyAccessor("field"),
		});

		// this is also a PERSONAL preference to only return fields that have a valid setter.
		_fields = this._resultClass.GetProperties(Flags).Where(x => x.GetSetMethod() != null).ToArray();
	}

	public object TransformTuple(object[] tuple, String[] aliases)
	{
		// fix issue #1: aliases in Oracle CreateSQLQuery 
		// returns all UPPERCASE no matter your object case. 
		// Using the fields generated in the constructor.
		if (_fields == null)
		{
			throw new ArgumentNullException("fields");
		}

		// this seems to address a similar issue:
		// https://hibernate.onjira.com/browse/HHH-2304
		// which also appears to exist in NHibernate
		var fieldNames = _fields.Select(x => x.Name).ToList();
		for (var i = 0; i < fieldNames.Count; i++)
		{
			var fieldType = _fields[i].PropertyType;
			if (fieldType.IsEnum)
			{
				// It can't seem to handle enums, so convert them 
				// to Int (so the enum will work)
				tuple[i] = Convert.ChangeType(tuple[i], TypeCode.Int32);
			}
			else
			{
				// set it to the actual field type on the property we're
				// filling.
				tuple[i] = Convert.ChangeType(tuple[i], fieldType);
			}
		}

		object result;

		try
		{
			if (_setters == null)
			{
				_setters = new ISetter[fieldNames.Count];
				for (var i = 0; i < fieldNames.Count; i++)
				{
					var fieldName = fieldNames[i];
					_setters[i] = _propertyAccessor.GetSetter(_resultClass, fieldName);
				}
			}

			// if resultClass is not a class but a value type, we need to use Activator.CreateInstance
			result = _resultClass.IsClass
						? _constructor.Invoke(null)
						: NHibernate.Cfg.Environment.BytecodeProvider.ObjectsFactory.CreateInstance(_resultClass, true);

			for (var i = 0; i < fieldNames.Count; i++)
			{
				if (_setters[i] != null)
				{
					_setters[i].Set(result, tuple[i]);
				}
			}
		}
		catch (InstantiationException e)
		{
			throw new HibernateException("Could not instantiate result class: " + _resultClass.FullName, e);
		}
		catch (MethodAccessException e)
		{
			throw new HibernateException("Could not instantiate result class: " + _resultClass.FullName, e);
		}

		return result;
	}

	public IList TransformList(IList collection)
	{
		return collection;
	}
}