LeftJoinExtension.LeftJoin<TFirst, TSecond, TKey, TResult>(IEnumerable<TFirst>, IEnumerable<TSecond>, Func<TFirst, TKey>, Func<TSecond, TKey>, Func<TFirst, TResult>, Func<TFirst, TSecond, TResult>) Method

Performs a left outer join on two heterogeneous sequences. Additional arguments specify key selection functions and result projection functions.

Definition

Namespace: MoreLinq.Extensions
Assembly: MoreLinq (in MoreLinq.dll) Version: 3.4.0+b99a6a8cc504caf2d48372fe54a2f8116c59cd0c

C#
public static IEnumerable<TResult> LeftJoin<TFirst, TSecond, TKey, TResult>(
	this IEnumerable<TFirst> first,
	IEnumerable<TSecond> second,
	Func<TFirst, TKey> firstKeySelector,
	Func<TSecond, TKey> secondKeySelector,
	Func<TFirst, TResult> firstSelector,
	Func<TFirst, TSecond, TResult> bothSelector
)

VB
<ExtensionAttribute>
Public Shared Function LeftJoin(Of TFirst, TSecond, TKey, TResult) ( 
	first As IEnumerable(Of TFirst),
	second As IEnumerable(Of TSecond),
	firstKeySelector As Func(Of TFirst, TKey),
	secondKeySelector As Func(Of TSecond, TKey),
	firstSelector As Func(Of TFirst, TResult),
	bothSelector As Func(Of TFirst, TSecond, TResult)
) As IEnumerable(Of TResult)

C++
public:
[ExtensionAttribute]
generic<typename TFirst, typename TSecond, typename TKey, typename TResult>
static IEnumerable<TResult>^ LeftJoin(
	IEnumerable<TFirst>^ first, 
	IEnumerable<TSecond>^ second, 
	Func<TFirst, TKey>^ firstKeySelector, 
	Func<TSecond, TKey>^ secondKeySelector, 
	Func<TFirst, TResult>^ firstSelector, 
	Func<TFirst, TSecond, TResult>^ bothSelector
)

F#
[<ExtensionAttribute>]
static member LeftJoin : 
        first : IEnumerable<'TFirst> * 
        second : IEnumerable<'TSecond> * 
        firstKeySelector : Func<'TFirst, 'TKey> * 
        secondKeySelector : Func<'TSecond, 'TKey> * 
        firstSelector : Func<'TFirst, 'TResult> * 
        bothSelector : Func<'TFirst, 'TSecond, 'TResult> -> IEnumerable<'TResult> 

Parameters

first IEnumerable<TFirst>: The first sequence of the join operation.
second IEnumerable<TSecond>: The second sequence of the join operation.
firstKeySelector Func<TFirst, TKey>: Function that projects the key given an element from first.
secondKeySelector Func<TSecond, TKey>: Function that projects the key given an element from second.
firstSelector Func<TFirst, TResult>: Function that projects the result given just an element from first where there is no corresponding element in second.
bothSelector Func<TFirst, TSecond, TResult>: Function that projects the result given an element from first and an element from second that match on a common key.

Type Parameters

TFirst: The type of elements in the first sequence.
TSecond: 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.

Return Value

IEnumerable<TResult>
A sequence containing results projected from a left outer join of the two input sequences.

Usage Note

In Visual Basic and C#, you can call this method as an instance method on any object of type IEnumerable<TFirst>. When you use instance method syntax to call this method, omit the first parameter. For more information, see Extension Methods (Visual Basic) or Extension Methods (C# Programming Guide).