Method RightOuterMergeJoin

RightOuterMergeJoin<TLeft, TRight, TKey>(IAsyncEnumerable<TLeft>, IAsyncEnumerable<TRight>, Func<TLeft, TKey>, Func<TRight, TKey>, IComparer<TKey>?)

Performs a right outer join on two heterogeneous sequences.

Declaration

public static IAsyncEnumerable<(TLeft? Left, TRight Right)> RightOuterMergeJoin<TLeft, TRight, TKey>(this IAsyncEnumerable<TLeft> left, IAsyncEnumerable<TRight> right, Func<TLeft, TKey> leftKeySelector, Func<TRight, TKey> rightKeySelector, IComparer<TKey>? comparer = null)

Parameters

Type	Name	Description
IAsyncEnumerable<TLeft>	left	The first sequence.
IAsyncEnumerable<TRight>	right	The second sequence.
Func<TLeft, TKey>	leftKeySelector	A function to extract the join key from each element of the first sequence.
Func<TRight, TKey>	rightKeySelector	A function to extract the join key from each element of the second sequence.
IComparer<TKey>	comparer	An IEqualityComparer<T> to hash and compare keys.

Returns

Type	Description
IAsyncEnumerable<(TLeft Left, TRight Right)>	A sequence containing values from a right outer join of the two input sequences.

Type Parameters

Name	Description
TLeft	The type of elements in the first sequence.
TRight	The type of elements in the second sequence.
TKey	The type of the key returned by the key selector functions.

Remarks

The result of this method is a `right outer`-join. All elements from right are returned, along with any matching elements from left, if any are present. If no values in left match, default is returned for the left element.

This method is implemented using a `merge`-join. The sequences left and right are assumed to be already sorted. Results from using unsorted sequences with this method are undefined. Each sequence is enumerated exactly once in a parallel fashion, until both sequences are fully enumerated.

This method uses deferred execution and streams its results.

Exceptions

Type	Condition
ArgumentNullException	left, right, leftKeySelector, or rightKeySelector is null.

RightOuterMergeJoin<TLeft, TRight, TKey, TResult>(IAsyncEnumerable<TLeft>, IAsyncEnumerable<TRight>, Func<TLeft, TKey>, Func<TRight, TKey>, Func<TRight, TResult>, Func<TLeft, TRight, TResult>, IComparer<TKey>?)

Performs a right outer join on two heterogeneous sequences.

Declaration

public static IAsyncEnumerable<TResult> RightOuterMergeJoin<TLeft, TRight, TKey, TResult>(this IAsyncEnumerable<TLeft> left, IAsyncEnumerable<TRight> right, Func<TLeft, TKey> leftKeySelector, Func<TRight, TKey> rightKeySelector, Func<TRight, TResult> rightResultSelector, Func<TLeft, TRight, TResult> bothResultSelector, IComparer<TKey>? comparer = null)

Parameters

Type	Name	Description
IAsyncEnumerable<TLeft>	left	The first sequence.
IAsyncEnumerable<TRight>	right	The second sequence.
Func<TLeft, TKey>	leftKeySelector	A function to extract the join key from each element of the first sequence.
Func<TRight, TKey>	rightKeySelector	A function to extract the join key from each element of the second sequence.
Func<TRight, TResult>	rightResultSelector	A function to create a result element from a right value that does not have a matching value in left.
Func<TLeft, TRight, TResult>	bothResultSelector	A function to create a result element from two matching elements.
IComparer<TKey>	comparer	An IEqualityComparer<T> to hash and compare keys.

Returns

Type	Description
IAsyncEnumerable<TResult>	A sequence containing values projected from a right outer join of the two input sequences.

Type Parameters

Name	Description
TLeft	The type of elements in the first sequence.
TRight	The type of elements in the second sequence.
TKey	The type of the key returned by the key selector functions.
TResult	The type of the result elements.

Remarks

The result of this method is a `left outer`-join. Values are projected using bothResultSelector when matching elements are found in both left and right sequences. Values are projected using rightResultSelector when elements in right do not have a matching element in left.

This method is implemented using a `merge`-join. The sequences left and right are assumed to be already sorted. Results from using unsorted sequences with this method are undefined. Each sequence is enumerated exactly once in a parallel fashion, until both sequences are fully enumerated.

This method uses deferred execution and streams its results.

Exceptions

Type	Condition
ArgumentNullException	left, right, leftKeySelector, rightKeySelector, rightResultSelector, or bothResultSelector is null.