/// <summary>
/// Returns the only document of the aggregate result, or the default value if the result set is empty. Throws an exception if the result set contains more than one document.
/// </summary>
/// <typeparam name="TResult">The type of the result.</typeparam>
/// <param name="aggregate">The aggregate.</param>
/// <param name="cancellationToken">The cancellation token.</param>
/// <returns>
/// The fluent aggregate interface.
/// </returns>
public static Task <TResult> SingleOrDefaultAsync <TResult>(this IAggregateFluent <TResult> aggregate, CancellationToken cancellationToken = default(CancellationToken))
{
Ensure.IsNotNull(aggregate, nameof(aggregate));
return(IAsyncCursorSourceExtensions.SingleOrDefaultAsync(aggregate.Limit(2), cancellationToken));
}
/// <summary>
/// Returns the first document of the aggregate result, or the default value if the result set is empty.
/// </summary>
/// <typeparam name="TResult">The type of the result.</typeparam>
/// <param name="aggregate">The aggregate.</param>
/// <param name="cancellationToken">The cancellation token.</param>
/// <returns>
/// The fluent aggregate interface.
/// </returns>
public static TResult FirstOrDefault <TResult>(this IAggregateFluent <TResult> aggregate, CancellationToken cancellationToken = default(CancellationToken))
{
Ensure.IsNotNull(aggregate, nameof(aggregate));
return(IAsyncCursorSourceExtensions.FirstOrDefault(aggregate.Limit(1), cancellationToken));
}
/// <summary>
/// Get the first result or null.
/// </summary>
/// <typeparam name="TDocument">The type of the document.</typeparam>
/// <typeparam name="TProjection">The type of the projection (same as TDocument if there is no projection).</typeparam>
/// <param name="find">The fluent find.</param>
/// <param name="cancellationToken">The cancellation token.</param>
/// <returns>A Task whose result is the first result or null.</returns>
public static Task <TProjection> FirstOrDefaultAsync <TDocument, TProjection>(this IFindFluent <TDocument, TProjection> find, CancellationToken cancellationToken = default(CancellationToken))
{
Ensure.IsNotNull(find, nameof(find));
return(IAsyncCursorSourceExtensions.FirstOrDefaultAsync(find.Limit(1), cancellationToken));
}