流利的NHibernate将非Id Guid映射到Oracle

Question

I'm trying to map a Guid, which is not an Id property, to an Oracle CLOB column.

In MsSQL I can map Guid to a UniqueIdentifier column as follows:

Map(x => x.Guid).Column("my_guid").CustomType<GuidType>();

and I generate the Guid in the constructor of my business entity:

public MyEntity()
{
    this.Guid = Guid.NewGuid();
}

However, when attempting to map Guid to a CLOB in Oracle, using the same mapping that works for MsSQL, it is always inserting a NULL value.

It would be convenient if this problem could be solved similar to how you map a Guid Id field:

Id(x => x.Id).Column("my_guid").GeneratedBy.GuidComb();

Answer 1

I couldn't really find a good way to do this, however, I have come up with a viable solution.

If we create a column in Oracle with datatype NOT NULL VARCHAR2(32) DEFAULT SYS_GUID() this will handle the generation of Guid when inserting a record.

However, Oracle generates Guid without hyphens so we get something that looks like EF8FDA432CB340ADE0434C687B89F91C .

Unfortunately because of this I had to create my own implementation of IUserType to handle the conversion of Guid with hyphens to Oracle's Guid stored as a VARCHAR2(32) without hyphens. The implementation is below:

[Serializable]
public class OracleGuidType : IUserType
{
    SqlType[] sqlTypes;

    public OracleGuidType()
    {
        // We use DbType.String here because we are storing as a varchar
        sqlTypes = new[] { SqlTypeFactory.GetSqlType(DbType.String, 0, 0) };
    }

    public SqlType[] SqlTypes
    {
        get { return sqlTypes; }
    }

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

    public object NullSafeGet(IDataReader rs, string[] names, object owner)
    {
        if (rs[names[0]] == DBNull.Value)
        {
            return Guid.Empty;
        }

        return new Guid(rs[names[0]].ToString());
    }

    public void NullSafeSet(IDbCommand cmd, object value, int index)
    {
        var param = (IDataParameter)cmd.Parameters[index];
        param.DbType = sqlTypes[0].DbType;
        var guid = (Guid)value;

        if (guid != Guid.Empty)
        {
            // This line removes hyphens
            param.Value = guid.ToString("N").ToUpper();
        }
        else
        {
            param.Value = DBNull.Value;
        }
    }

    public bool IsMutable
    {
        get { return false; }
    }

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

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

    public object Assemble(object cached, object owner)
    {
        return cached;
    }

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

    public new bool Equals(object x, object y)
    {
        return x != null && x.Equals(y);
    }

    public int GetHashCode(object x)
    {
        return x.GetHashCode();
    }
}

And my NHibernate mapping is defined as:

Map(x => x.Guid).Column("my_guid").Generated.Insert().CustomType<OracleGuidType>();