/// <summary>
/// Generates an id for the specified entity.
/// </summary>
/// <param name="entity">The entity.</param>
/// <param name="idMap">The id map.</param>
/// <returns></returns>
/// <remarks>
/// This code was taken from NHibernate.
/// </remarks>
public object Generate(object entity, IdMap idMap)
{
var guidArray = Guid.NewGuid().ToByteArray();
var baseDate = new DateTime(1900, 1, 1);
var now = DateTime.Now;
// Get the days and milliseconds which will be used to build the byte string
var days = new TimeSpan(now.Ticks - baseDate.Ticks);
var msecs = now.TimeOfDay;
// Convert to a byte array
// Note that SQL Server is accurate to 1/300th of a millisecond so we divide by 3.333333
var daysArray = BitConverter.GetBytes(days.Days);
var msecsArray = BitConverter.GetBytes((long)(msecs.TotalMilliseconds / 3.333333));
// Reverse the bytes to match SQL Servers ordering
Array.Reverse(daysArray);
Array.Reverse(msecsArray);
// Copy the bytes into the guid
Array.Copy(daysArray, daysArray.Length - 2, guidArray, guidArray.Length - 6, 2);
Array.Copy(msecsArray, msecsArray.Length - 4, guidArray, guidArray.Length - 4, 4);
return new Guid(guidArray);
}
/// <summary>
/// Gets the id of the specified entitiy.
/// </summary>
/// <param name = "entity">The entity.</param>
/// <returns></returns>
public object GetId(object entity)
{
if (!HasId)
{
throw new InvalidCastException(string.Format("{0} does not have a mapped id.", ClassType));
}
return(IdMap.GetValue(entity));
}
/// <summary>
/// Generates an id for the specified entity.
/// </summary>
/// <param name="entity">The entity.</param>
/// <param name="idMap">The id map.</param>
/// <returns></returns>
public object Generate(object entity, IdMap idMap)
{
var id = idMap.GetValue(entity);
if (Equals(id, idMap.UnsavedValue))
throw new IdGenerationException(string.Format("Ids for {0} must be manually assigned before saving.", entity.GetType()));
return id;
}
/// <summary>
/// Generates an id for the specified entity.
/// </summary>
/// <param name="entity">The entity.</param>
/// <param name="idMap">The id map.</param>
/// <returns></returns>
public object Generate(object entity, IdMap idMap)
{
return Oid.NewOid();
}
