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ObservableAsync.FirstAsync(IObservableAsync, Func) method¶

Defined in

Type: ObservableAsync Namespace: ReactiveUI.Extensions.Async Assembly: ReactiveUI.Extensions.dll

Applies to

net10.0, net10.0-browserwasm1.0, net10.0-desktop1.0, net9.0, net9.0-browserwasm1.0, net9.0-desktop1.0, net8.0, net8.0-ios17.5, net8.0-maccatalyst17.5, net8.0-macos14.2, net8.0-macos14.5, net8.0-tvos17.2, netstandard2.1, net462, net481

Overloads¶

1. public static ValueTask<T> FirstAsync<T>(this IObservableAsync<T> @this, Func<T, bool> predicate)
2. public static ValueTask<T> FirstAsync<T>(this IObservableAsync<T> @this, Func<T, bool> predicate, CancellationToken cancellationToken)
3. public static ValueTask<T> FirstAsync<T>(this IObservableAsync<T> @this)
4. public static ValueTask<T> FirstAsync<T>(this IObservableAsync<T> @this, CancellationToken cancellationToken)

1. Overload¶

public static ValueTask<T> FirstAsync<T>(this IObservableAsync<T> @this, Func<T, bool> predicate)

View source

Summary: Asynchronously returns the first element in the sequence that satisfies the specified predicate.

Type parameters

Name	Description
`T`	The type of elements in the sequence.

Parameters

Name	Type	Description
`this`	[IObservableAsync](#	The source observable sequence.
`predicate`	Func	A function to test each element for a condition. The method returns the first element for which this predicate returns `true`.

Returns: ValueTask -- A task that represents the asynchronous operation. The task result contains the first element that matches the predicate.

2. Overload¶

public static ValueTask<T> FirstAsync<T>(this IObservableAsync<T> @this, Func<T, bool> predicate, CancellationToken cancellationToken)

Summary: Asynchronously returns the first element in the sequence that satisfies the specified predicate.

Type parameters

Name	Description
`T`	The type of elements in the sequence.

Parameters

Name	Type	Description
`this`	[IObservableAsync](#	The source observable sequence.
`predicate`	Func	A function to test each element for a condition. The method returns the first element for which this predicate returns `true`.
`cancellationToken`	CancellationToken	A cancellation token that can be used to cancel the asynchronous operation.

Returns: ValueTask -- A task that represents the asynchronous operation. The task result contains the first element that matches the predicate.

3. Overload¶

public static ValueTask<T> FirstAsync<T>(this IObservableAsync<T> @this)

View source

Summary: Asynchronously returns the first element of the sequence.

Type parameters

Name	Description
`T`	The type of elements in the sequence.

Parameters

Name	Type	Description
`this`	[IObservableAsync](#	The source observable sequence.

Returns: ValueTask -- A task that represents the asynchronous operation. The task result contains the first element of the sequence.

Remarks

If the sequence is empty, the behavior depends on the implementation and may result in an exception being thrown.

4. Overload¶

public static ValueTask<T> FirstAsync<T>(this IObservableAsync<T> @this, CancellationToken cancellationToken)

Summary: Asynchronously returns the first element of the sequence.

Type parameters

Name	Description
`T`	The type of elements in the sequence.

Parameters

Name	Type	Description
`this`	[IObservableAsync](#	The source observable sequence.
`cancellationToken`	CancellationToken	A cancellation token that can be used to cancel the asynchronous operation.

Returns: ValueTask -- A task that represents the asynchronous operation. The task result contains the first element of the sequence.

Remarks

If the sequence is empty, the behavior depends on the implementation and may result in an exception being thrown.