nhibernate如何在Mysql中存储TimeSpan？

<property name="Duration" column="duration" type="TimeAsTimeSpan" />

public class TimeAsTimeSpanType : IUserType
{
    public SqlType[] SqlTypes => new[] { NHibernateUtil.TimeSpan.SqlType };

    public Type ReturnedType => typeof(TimeSpan);

    public bool IsMutable => false;

    public object NullSafeGet(IDataReader rs, string[] names, object owner)
    {
        var value = NHibernateUtil.TimeSpan.NullSafeGet(rs, names[0]);
        if (value == null)
            return null;

        var ticks = TimeSpan.Parse(value.ToString()).Ticks;
        return new TimeSpan(ticks);
    }

    public void NullSafeSet(IDbCommand cmd, object value, int index)
    {
        if (value == null)
        {
            ((IDataParameter)cmd.Parameters[index]).Value = DBNull.Value;
        }
        else
        {
            var timeSpan = (TimeSpan)value;
            ((IDataParameter)cmd.Parameters[index]).Value = timeSpan.ToString();
        }
    }

    // 省略其他方法的实现
}

<property name="hibernate.connection.provider" value="NHibernate.Connection.DriverConnectionProvider" />
<property name="hibernate.dialect" value="NHibernate.Dialect.MySQLDialect" />
<property name="hibernate.connection.driver_class" value="NHibernate.Driver.MySqlDataDriver" />
<property name="hibernate.connection.connection_string" value="your_connection_string" />
<property name="hibernate.show_sql" value="true" />

<typedef name="TimeAsTimeSpan" class="YourNamespace.TimeAsTimeSpanType, YourAssembly" />

public class YourEntity
{
    public virtual TimeSpan Duration { get; set; }
}