/// <summary>
/// Executes a given <see cref="IQuery"/> and uses a delegate to convert the results into arbitrary objects. The result sequence may be lazy and
/// streamed, i.e., the query results may be gathered while the sequence is enumerated. The underlying <see cref="StorageProvider" /> may keep
/// resources (such as a database connection) open while the sequence is enumerated, see remarks.
/// </summary>
/// <typeparam name="T">The type of values to be returned by the query.</typeparam>
/// <param name="query">The query to execute. Must not be <see langword="null"/>.</param>
/// <param name="rowReader">A delegate that is used to convert the query result, represented as an <see cref="IQueryResultRow"/>,
/// into the query result type, <typeparamref name="T"/>.</param>
/// <returns>A collection containing the objects produced by the <paramref name="rowReader"/>-delegate.</returns>
/// <remarks>
/// The underlying <see cref="StorageProvider" /> may implement this method in such a way that the query is only executed when the returned
/// <see cref="IEnumerable{T}"/> is enumerated. Resources, such as a database connection or transaction, may be kept open during that
/// enumeration until the <see cref="IEnumerator{T}"/> is disposed. Use "<see cref="Enumerable"/>.ToArray()" or iterate immediately if you require
/// those resources to be freed as quickly as possible.
/// </remarks>
public IEnumerable <T> GetCustom <T> (IQuery query, Func <IQueryResultRow, T> rowReader)
{
ArgumentUtility.CheckNotNull("query", query);
ArgumentUtility.CheckNotNull("rowReader", rowReader);
if (query.QueryType != QueryType.Custom)
{
throw new ArgumentException("A collection or scalar query cannot be used with GetCustom.", "query");
}
if (query.EagerFetchQueries.Count > 0)
{
throw new ArgumentException("A custom query cannot have eager fetch queries defined.", "query");
}
var queryResult = _persistenceStrategy.ExecuteCustomQuery(query).Select(rowReader);
return(_transactionEventSink.RaiseFilterCustomQueryResultEvent(query, queryResult));
}