/// <summary>
/// Selects a record of the specified type from a partitioned table in the database by its id and timestamp.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="session"></param>
/// <param name="id"></param>
/// <param name="timestamp"></param>
/// <returns></returns>
public static object Get(Type type, ISession session, object id, object partitionKey, bool forUpdate = false)
{
// Make sure the mappings have been loaded for this type.
LoadMappings(type);
try
{
TableMapping mapping = _mappings[type];
// If caching is enabled for this entity type, check if it is in cache already.
if (mapping.CachingEnabled && SessionFactory.CachingEnabled)
{
object cachedEntity = GetCachedEntity(type, id);
if (cachedEntity != null)
{
return(cachedEntity);
}
}
// Make sure that the table is not partitioned.
if (mapping.IsPartitioned && partitionKey == null)
{
throw new Exception("Cannot select an object from a partitioned table without a partition key.");
}
//SqlCommand selectCommand = new SqlCommand(mapping.GetExpression, (SqlConnection)session.Connection);
IDbCommand selectCommand = session.Connection.CreateCommand();
selectCommand.CommandText = mapping.GetExpression;
if (forUpdate)
{
selectCommand.CommandText = String.Concat(selectCommand.CommandText, " FOR UPDATE");
}
// Get the primary key column(s).
List <ColumnMapping> idColumns = mapping.Columns.Where(c => c.IsPk).ToList();
// Check if we have multiple PKs or just one.
if (idColumns.Count == 1)
{
AddParameter(selectCommand, "p_id0", idColumns[0].DbType, id);
}
else
{
int i = 0;
// If we have multiple PKs then add a parameter for each of them.
foreach (ColumnMapping idColumn in idColumns)
{
AddParameter(selectCommand, String.Format("p_id{0}", i++), idColumn.DbType, idColumn.PropertyInfo.GetValue(id, null));
}
}
// Add the partition key timestamp parameter.
if (mapping.IsPartitioned)
{
ColumnMapping idColumn = mapping.Columns.FirstOrDefault(c => c.IsPartitionKey);
AddParameter(selectCommand, "p_ts", idColumn.DbType, partitionKey);
}
LogCommand(selectCommand);
object entity = null;
using (IDataReader reader = selectCommand.ExecuteReader())
{
if (reader.Read())
{
entity = FromDb(type, reader);
}
}
return(entity);
}
catch (Exception ex) { Log.Error("DataMapper.Get threw an exception.", ex); }
return(null);
}
/// <summary>
/// Gets the database session key for the specified entity type.
/// </summary>
/// <param name="entityType"></param>
/// <returns></returns>
internal static string GetSessionKey(Type entityType)
{
TableMapping mapping = DataMapper.GetTableMapping(entityType);
return((mapping == null) ? null : mapping.Key);
}
