Method FirstOrDefaultAsync
FirstOrDefaultAsync<TSource>(IMongoQueryable<TSource>, CancellationToken)
Returns the first element of a sequence, or a default value if the sequence contains no elements.
public static Task<TSource> FirstOrDefaultAsync<TSource>(this IMongoQueryable<TSource> source, CancellationToken cancellationToken = default)
Parameters
source
IMongoQueryable<TSource>The IMongoQueryable<T> to return the first element of.
cancellationToken
CancellationTokenThe cancellation token.
Returns
- Task<TSource>
default(
TSource
) ifsource
is empty; otherwise, the first element insource
.
Type Parameters
TSource
The type of the elements of
source
.
FirstOrDefaultAsync<TSource>(IMongoQueryable<TSource>, Expression<Func<TSource, bool>>, CancellationToken)
Returns the first element of a sequence that satisfies a specified condition or a default value if no such element is found.
public static Task<TSource> FirstOrDefaultAsync<TSource>(this IMongoQueryable<TSource> source, Expression<Func<TSource, bool>> predicate, CancellationToken cancellationToken = default)
Parameters
source
IMongoQueryable<TSource>An IMongoQueryable<T> to return an element from.
predicate
Expression<Func<TSource, bool>>A function to test each element for a condition.
cancellationToken
CancellationTokenThe cancellation token.
Returns
- Task<TSource>
default(
TSource
) ifsource
is empty or if no element passes the test specified bypredicate
; otherwise, the first element insource
that passes the test specified bypredicate
.
Type Parameters
TSource
The type of the elements of
source
.