/// <summary>
/// Converts an IDataReader to a single object.
/// </summary>
/// <typeparam name="T">The expected type of the object.</typeparam>
/// <param name="reader">The data reader.</param>
/// <param name="withGraph">The type of object graph to use to deserialize the object.</param>
/// <returns>A list of objects.</returns>
public static T Single <T>(this IDataReader reader, Type withGraph)
{
T t = reader.AsEnumerable <T>(withGraph).FirstOrDefault();
reader.Advance();
return(t);
}
/// <summary>
/// Converts an IDataReader to a single object, using the specified record reader.
/// </summary>
/// <typeparam name="T">The expected type of the object.</typeparam>
/// <param name="reader">The data reader.</param>
/// <param name="recordReader">The the record reader to use.</param>
/// <returns>A list of objects.</returns>
public static T Single <T>(this IDataReader reader, IRecordReader <T> recordReader)
{
if (reader == null)
{
throw new ArgumentNullException("reader");
}
if (recordReader == null)
{
throw new ArgumentNullException("recordReader");
}
if (reader.IsClosed)
{
return(default(T));
}
// get the mapper
var mapper = recordReader.GetRecordReader(reader);
try
{
if (reader.Read())
{
return(mapper(reader));
}
else
{
return(default(T));
}
}
finally
{
reader.Advance();
}
}
/// <summary>
/// Converts an IDataReader to an enumerable. The reader is closed after all records are read.
/// </summary>
/// <typeparam name="T">The type of object to return.</typeparam>
/// <param name="reader">The data reader.</param>
/// <param name="recordReader">The record reader to use.</param>
/// <returns>An enumerable over the return results.</returns>
/// <remarks>
/// If you use this method and are relying on CommandBehavior.CloseConnection to close the connection, note that if all of the records are not read
/// (due to an exception or otherwise), then the connection will leak until GC is run. Your code is responsible for closing the connection.
/// </remarks>
public static IEnumerable <T> AsEnumerable <T>(this IDataReader reader, IRecordReader <T> recordReader)
{
// if the reader is closed, then we return an empty list, rather than blowing up
if (reader.IsClosed)
{
yield break;
}
// get the mapper
var mapper = recordReader.GetRecordReader(reader);
// read in all of the objects from the reader
while (reader.Read())
{
yield return(mapper(reader));
}
// advance to the next recordset
reader.Advance();
}
