/// <summary>
/// Asynchronously returns the first element of a sequence, or a default value if the sequence contains no elements.
/// </summary>
/// <remarks>
/// Multiple active operations on the same context instance are not supported. Use 'await' to ensure
/// that any asynchronous operations have completed before calling another method on this context.
/// </remarks>
/// <typeparam name="TSource">
/// The type of the elements of <paramref name="source" />.
/// </typeparam>
/// <param name="source">
/// An <see cref="IQueryable{T}" /> to return the first element of.
/// </param>
/// <param name="cancellationToken">
/// A <see cref="CancellationToken" /> to observe while waiting for the task to complete.
/// </param>
/// <returns>
/// A task that represents the asynchronous operation.
/// The task result contains <see langword="default" /> ( <typeparamref name="TSource" /> ) if
/// <paramref name="source" /> is empty; otherwise, the first element in <paramref name="source" />.
/// </returns>
/// <exception cref="ArgumentNullException">
/// <paramref name="source" /> is <see langword="null" />.
/// </exception>
public static Task <TSource> FirstOrDefaultAsync <TSource>(
this IYahooQueryable <TSource> source,
CancellationToken cancellationToken = default
) where TSource : IYahooCollection
{
return(ExecuteAsync <TSource, TSource>(
QueryableMethods.FirstOrDefaultWithoutPredicate,
source,
cancellationToken
));
}
/// <summary>
/// Returns an <see cref="IAsyncEnumerable{T}" /> which can be enumerated asynchronously.
/// </summary>
/// <remarks>
/// Multiple active operations on the same context instance are not supported. Use 'await' to ensure
/// that any asynchronous operations have completed before calling another method on this context.
/// </remarks>
/// <typeparam name="TSource">
/// The type of the elements of <paramref name="source" />.
/// </typeparam>
/// <param name="source">
/// An <see cref="IQueryable{T}" /> to enumerate.
/// </param>
/// <returns> The query results. </returns>
/// <exception cref="InvalidOperationException">
/// <paramref name="source" /> is <see langword="null" />.
/// </exception>
/// <exception cref="ArgumentNullException">
/// <paramref name="source" /> is not a <see cref="IAsyncEnumerable{T}" />.
/// </exception>
public static IAsyncEnumerable <TSource> AsAsyncEnumerable <TSource>(
this IYahooQueryable <TSource> source
) where TSource : IYahooCollection
{
if (source is IAsyncEnumerable <TSource> asyncEnumerable)
{
return(asyncEnumerable);
}
throw new InvalidOperationException(
$"The source 'IQueryable' doesn't implement 'IAsyncEnumerable<{typeof(TSource)}>'. Only sources that implement 'IAsyncEnumerable' can be used for asynchronous operations."
);
}
public static IYahooQueryable <TYahooEntity, Game> Filter <TYahooEntity>(
this IYahooQueryable <TYahooEntity, Game> source,
GameCollectionFilters filters
) where TYahooEntity : IYahooEntity =>
new YahooCollection <TYahooEntity, Game>(
source.Provider is YahooQueryProvider
? source.Provider.CreateQuery <TYahooEntity>(
Expression.Call(
instance : null,
method : GameFilterMethodInfo.MakeGenericMethod(typeof(TYahooEntity)),
arguments : new[] { source.Expression, Expression.Constant(filters) }
)
)
: source
);
/// <summary>
/// Asynchronously creates a <see cref="List{T}" /> from an <see cref="IQueryable{T}" /> by enumerating it
/// asynchronously.
/// </summary>
/// <remarks>
/// Multiple active operations on the same context instance are not supported. Use 'await' to ensure
/// that any asynchronous operations have completed before calling another method on this context.
/// </remarks>
/// <typeparam name="TSource">
/// The type of the elements of <paramref name="source" />.
/// </typeparam>
/// <param name="source">
/// An <see cref="IQueryable{T}" /> to create a list from.
/// </param>
/// <param name="cancellationToken">
/// A <see cref="CancellationToken" /> to observe while waiting for the task to complete.
/// </param>
/// <returns>
/// A task that represents the asynchronous operation.
/// The task result contains a <see cref="List{T}" /> that contains elements from the input sequence.
/// </returns>
/// <exception cref="ArgumentNullException">
/// <paramref name="source" /> is <see langword="null" />.
/// </exception>
public static async Task <List <TSource> > ToListAsync <TSource>(
this IYahooQueryable <TSource> source,
CancellationToken cancellationToken = default
) where TSource : IYahooCollection
{
var list = new List <TSource>();
await foreach (
var element in source.AsAsyncEnumerable().WithCancellation(cancellationToken)
)
{
list.Add(element);
}
return(list);
}
public static IYahooQueryable <TSource, TSubCollection> SubResource <
TSource,
TPrevSubCollection,
TSubCollection
>(
this IYahooQueryable <TSource, TPrevSubCollection> source,
Expression <Func <TPrevSubCollection, IEnumerable <TSubCollection> > > expression
) where TSource : IYahooEntity
where TPrevSubCollection : IYahooEntity
where TSubCollection : IYahooCollection =>
new YahooCollection <TSource, TSubCollection>(
source.Provider.CreateQuery <TSource>(
Expression.Call(
instance : null,
method : CollectionNextSubResourceMethodInfo.MakeGenericMethod(
typeof(TSource),
typeof(TPrevSubCollection),
typeof(TSubCollection)
),
arguments : new[] { source.Expression, Expression.Quote(expression) }
)
)
);
/// <summary>
/// Asynchronously creates an array from an <see cref="IQueryable{T}" /> by enumerating it asynchronously.
/// </summary>
/// <remarks>
/// Multiple active operations on the same context instance are not supported. Use 'await' to ensure
/// that any asynchronous operations have completed before calling another method on this context.
/// </remarks>
/// <typeparam name="TSource">
/// The type of the elements of <paramref name="source" />.
/// </typeparam>
/// <param name="source">
/// An <see cref="IQueryable{T}" /> to create an array from.
/// </param>
/// <param name="cancellationToken">
/// A <see cref="CancellationToken" /> to observe while waiting for the task to complete.
/// </param>
/// <returns>
/// A task that represents the asynchronous operation.
/// The task result contains an array that contains elements from the input sequence.
/// </returns>
/// <exception cref="ArgumentNullException">
/// <paramref name="source" /> is <see langword="null" />.
/// </exception>
public static async Task <TSource[]> ToArrayAsync <TSource>(
this IYahooQueryable <TSource> source,
CancellationToken cancellationToken = default
) where TSource : IYahooCollection =>
(await source.ToListAsync(cancellationToken).ConfigureAwait(false)).ToArray();
