Enumerable.GroupJoin Método

public:
generic <typename TOuter, typename TInner, typename TKey, typename TResult>
[System::Runtime::CompilerServices::Extension]
 static System::Collections::Generic::IEnumerable<TResult> ^ GroupJoin(System::Collections::Generic::IEnumerable<TOuter> ^ outer, System::Collections::Generic::IEnumerable<TInner> ^ inner, Func<TOuter, TKey> ^ outerKeySelector, Func<TInner, TKey> ^ innerKeySelector, Func<TOuter, System::Collections::Generic::IEnumerable<TInner> ^, TResult> ^ resultSelector, System::Collections::Generic::IEqualityComparer<TKey> ^ comparer);

public static System.Collections.Generic.IEnumerable<TResult> GroupJoin<TOuter,TInner,TKey,TResult> (this System.Collections.Generic.IEnumerable<TOuter> outer, System.Collections.Generic.IEnumerable<TInner> inner, Func<TOuter,TKey> outerKeySelector, Func<TInner,TKey> innerKeySelector, Func<TOuter,System.Collections.Generic.IEnumerable<TInner>,TResult> resultSelector, System.Collections.Generic.IEqualityComparer<TKey> comparer);

public static System.Collections.Generic.IEnumerable<TResult> GroupJoin<TOuter,TInner,TKey,TResult> (this System.Collections.Generic.IEnumerable<TOuter> outer, System.Collections.Generic.IEnumerable<TInner> inner, Func<TOuter,TKey> outerKeySelector, Func<TInner,TKey> innerKeySelector, Func<TOuter,System.Collections.Generic.IEnumerable<TInner>,TResult> resultSelector, System.Collections.Generic.IEqualityComparer<TKey>? comparer);

static member GroupJoin : seq<'Outer> * seq<'Inner> * Func<'Outer, 'Key> * Func<'Inner, 'Key> * Func<'Outer, seq<'Inner>, 'Result> * System.Collections.Generic.IEqualityComparer<'Key> -> seq<'Result>

<Extension()>
Public Function GroupJoin(Of TOuter, TInner, TKey, TResult) (outer As IEnumerable(Of TOuter), inner As IEnumerable(Of TInner), outerKeySelector As Func(Of TOuter, TKey), innerKeySelector As Func(Of TInner, TKey), resultSelector As Func(Of TOuter, IEnumerable(Of TInner), TResult), comparer As IEqualityComparer(Of TKey)) As IEnumerable(Of TResult)

Parámetros de tipo

Parámetros

Devoluciones

IEnumerable<TResult>

IEnumerable<T> que contiene elementos de tipo TResult que se han obtenido al realizar una combinación agrupada de dos secuencias.An IEnumerable<T> that contains elements of type TResult that are obtained by performing a grouped join on two sequences.

Excepciones

Comentarios

Este método se implementa mediante la ejecución aplazada.This method is implemented by using deferred execution. El valor devuelto inmediato es un objeto que almacena toda la información necesaria para realizar la acción.The immediate return value is an object that stores all the information that is required to perform the action. La consulta representada por este método no se ejecuta hasta que el objeto se enumera mediante una llamada a su GetEnumerator método directamente o mediante foreach en Visual C# o For Each en Visual Basic.The query represented by this method is not executed until the object is enumerated either by calling its GetEnumerator method directly or by using foreach in Visual C# or For Each in Visual Basic.

Si comparer es null , el comparador de igualdad predeterminado, Default , se usa para aplicar un algoritmo hash y comparar claves.If comparer is null, the default equality comparer, Default, is used to hash and compare keys.

GroupJoin genera resultados jerárquicos, lo que significa que los elementos de outer se emparejan con colecciones de elementos coincidentes de inner .GroupJoin produces hierarchical results, which means that elements from outer are paired with collections of matching elements from inner. GroupJoin permite basar los resultados en un conjunto completo de coincidencias para cada elemento de outer .GroupJoin enables you to base your results on a whole set of matches for each element of outer.

resultSelectorSolo se llama a la función una vez para cada outer elemento junto con una colección de todos los inner elementos que coinciden con el outer elemento.The resultSelector function is called only one time for each outer element together with a collection of all the inner elements that match the outer element. Esto difiere del Join método en el que la función del selector de resultados se invoca en pares que contienen un elemento de outer y un elemento de inner .This differs from the Join method in which the result selector function is invoked on pairs that contain one element from outer and one element from inner.

GroupJoin conserva el orden de los elementos de outer , y para cada elemento de outer , el orden de los elementos coincidentes de inner .GroupJoin preserves the order of the elements of outer, and for each element of outer, the order of the matching elements from inner.

GroupJoin no tiene ningún equivalente directo en términos de base de datos relacional tradicional.GroupJoin has no direct equivalent in traditional relational database terms. Sin embargo, este método implementa un superconjunto de combinaciones internas y combinaciones externas izquierdas.However, this method does implement a superset of inner joins and left outer joins. Ambas operaciones se pueden escribir en términos de una combinación agrupada.Both of these operations can be written in terms of a grouped join. Vea operaciones de combinación.See Join Operations.

Consulte también

• Realizar operaciones de combinaciónPerforming Join Operations

public:
generic <typename TOuter, typename TInner, typename TKey, typename TResult>
[System::Runtime::CompilerServices::Extension]
 static System::Collections::Generic::IEnumerable<TResult> ^ GroupJoin(System::Collections::Generic::IEnumerable<TOuter> ^ outer, System::Collections::Generic::IEnumerable<TInner> ^ inner, Func<TOuter, TKey> ^ outerKeySelector, Func<TInner, TKey> ^ innerKeySelector, Func<TOuter, System::Collections::Generic::IEnumerable<TInner> ^, TResult> ^ resultSelector);

public static System.Collections.Generic.IEnumerable<TResult> GroupJoin<TOuter,TInner,TKey,TResult> (this System.Collections.Generic.IEnumerable<TOuter> outer, System.Collections.Generic.IEnumerable<TInner> inner, Func<TOuter,TKey> outerKeySelector, Func<TInner,TKey> innerKeySelector, Func<TOuter,System.Collections.Generic.IEnumerable<TInner>,TResult> resultSelector);

static member GroupJoin : seq<'Outer> * seq<'Inner> * Func<'Outer, 'Key> * Func<'Inner, 'Key> * Func<'Outer, seq<'Inner>, 'Result> -> seq<'Result>

<Extension()>
Public Function GroupJoin(Of TOuter, TInner, TKey, TResult) (outer As IEnumerable(Of TOuter), inner As IEnumerable(Of TInner), outerKeySelector As Func(Of TOuter, TKey), innerKeySelector As Func(Of TInner, TKey), resultSelector As Func(Of TOuter, IEnumerable(Of TInner), TResult)) As IEnumerable(Of TResult)

Parámetros de tipo

Parámetros

Devoluciones

IEnumerable<TResult>

IEnumerable<T> que contiene elementos de tipo TResult que se han obtenido al realizar una combinación agrupada de dos secuencias.An IEnumerable<T> that contains elements of type TResult that are obtained by performing a grouped join on two sequences.

Excepciones

Ejemplos

En el ejemplo de código siguiente se muestra cómo utilizar GroupJoin<TOuter,TInner,TKey,TResult>(IEnumerable<TOuter>, IEnumerable<TInner>, Func<TOuter,TKey>, Func<TInner,TKey>, Func<TOuter,IEnumerable<TInner>,TResult>) para realizar una combinación agrupada en dos secuencias.The following code example demonstrates how to use GroupJoin<TOuter,TInner,TKey,TResult>(IEnumerable<TOuter>, IEnumerable<TInner>, Func<TOuter,TKey>, Func<TInner,TKey>, Func<TOuter,IEnumerable<TInner>,TResult>) to perform a grouped join on two sequences.

class Person
{
    public string Name { get; set; }
}

class Pet
{
    public string Name { get; set; }
    public Person Owner { get; set; }
}

public static void GroupJoinEx1()
{
    Person magnus = new Person { Name = "Hedlund, Magnus" };
    Person terry = new Person { Name = "Adams, Terry" };
    Person charlotte = new Person { Name = "Weiss, Charlotte" };

    Pet barley = new Pet { Name = "Barley", Owner = terry };
    Pet boots = new Pet { Name = "Boots", Owner = terry };
    Pet whiskers = new Pet { Name = "Whiskers", Owner = charlotte };
    Pet daisy = new Pet { Name = "Daisy", Owner = magnus };

    List<Person> people = new List<Person> { magnus, terry, charlotte };
    List<Pet> pets = new List<Pet> { barley, boots, whiskers, daisy };

    // Create a list where each element is an anonymous
    // type that contains a person's name and
    // a collection of names of the pets they own.
    var query =
        people.GroupJoin(pets,
                         person => person,
                         pet => pet.Owner,
                         (person, petCollection) =>
                             new
                             {
                                 OwnerName = person.Name,
                                 Pets = petCollection.Select(pet => pet.Name)
                             });

    foreach (var obj in query)
    {
        // Output the owner's name.
        Console.WriteLine("{0}:", obj.OwnerName);
        // Output each of the owner's pet's names.
        foreach (string pet in obj.Pets)
        {
            Console.WriteLine("  {0}", pet);
        }
    }
}

/*
 This code produces the following output:

 Hedlund, Magnus:
   Daisy
 Adams, Terry:
   Barley
   Boots
 Weiss, Charlotte:
   Whiskers
*/

Structure Person
    Public Name As String
End Structure

Structure Pet
    Public Name As String
    Public Owner As Person
End Structure

Sub GroupJoinEx1()
    Dim magnus As New Person With {.Name = "Hedlund, Magnus"}
    Dim terry As New Person With {.Name = "Adams, Terry"}
    Dim charlotte As New Person With {.Name = "Weiss, Charlotte"}

    Dim barley As New Pet With {.Name = "Barley", .Owner = terry}
    Dim boots As New Pet With {.Name = "Boots", .Owner = terry}
    Dim whiskers As New Pet With {.Name = "Whiskers", .Owner = charlotte}
    Dim daisy As New Pet With {.Name = "Daisy", .Owner = magnus}

    Dim people As New List(Of Person)(New Person() {magnus, terry, charlotte})
    Dim pets As New List(Of Pet)(New Pet() {barley, boots, whiskers, daisy})

    ' Create a collection where each element is an anonymous type
    ' that contains a Person's name and a collection of names of 
    ' the pets that are owned by them.
    Dim query =
people.GroupJoin(pets,
           Function(person) person,
           Function(pet) pet.Owner,
           Function(person, petCollection) _
               New With {.OwnerName = person.Name,
                         .Pets = petCollection.Select(
                                            Function(pet) pet.Name)})

    Dim output As New System.Text.StringBuilder
    For Each obj In query
        ' Output the owner's name.
        output.AppendLine(obj.OwnerName & ":")
        ' Output each of the owner's pet's names.
        For Each pet As String In obj.Pets
            output.AppendLine("  " & pet)
        Next
    Next

    ' Display the output.
    Console.WriteLine(output.ToString)
End Sub

' This code produces the following output:
'
' Hedlund, Magnus
'   Daisy
' Adams, Terry
'   Barley
'   Boots
' Weiss, Charlotte
'   Whiskers

Comentarios

Este método se implementa mediante la ejecución aplazada.This method is implemented by using deferred execution. El valor devuelto inmediato es un objeto que almacena toda la información necesaria para realizar la acción.The immediate return value is an object that stores all the information that is required to perform the action. La consulta representada por este método no se ejecuta hasta que el objeto se enumera mediante una llamada a su GetEnumerator método directamente o mediante foreach en Visual C# o For Each en Visual Basic.The query represented by this method is not executed until the object is enumerated either by calling its GetEnumerator method directly or by using foreach in Visual C# or For Each in Visual Basic.

El comparador de igualdad predeterminado, Default , se usa para aplicar un algoritmo hash y comparar claves.The default equality comparer, Default, is used to hash and compare keys.

GroupJoin genera resultados jerárquicos, lo que significa que los elementos de outer se emparejan con colecciones de elementos coincidentes de inner .GroupJoin produces hierarchical results, which means that elements from outer are paired with collections of matching elements from inner. GroupJoin permite basar los resultados en un conjunto completo de coincidencias para cada elemento de outer .GroupJoin enables you to base your results on a whole set of matches for each element of outer.

resultSelectorSolo se llama a la función una vez para cada outer elemento junto con una colección de todos los inner elementos que coinciden con el outer elemento.The resultSelector function is called only one time for each outer element together with a collection of all the inner elements that match the outer element. Esto difiere del Join método, en el que la función del selector de resultados se invoca en pares que contienen un elemento de outer y un elemento de inner .This differs from the Join method, in which the result selector function is invoked on pairs that contain one element from outer and one element from inner.

GroupJoin conserva el orden de los elementos de outer , y para cada elemento de outer , el orden de los elementos coincidentes de inner .GroupJoin preserves the order of the elements of outer, and for each element of outer, the order of the matching elements from inner.

GroupJoin no tiene ningún equivalente directo en términos de base de datos relacional tradicional.GroupJoin has no direct equivalent in traditional relational database terms. Sin embargo, este método implementa un superconjunto de combinaciones internas y combinaciones externas izquierdas.However, this method does implement a superset of inner joins and left outer joins. Ambas operaciones se pueden escribir en términos de una combinación agrupada.Both of these operations can be written in terms of a grouped join. Vea operaciones de combinación.See Join Operations.

En la sintaxis de las expresiones de consulta, una join … into cláusula (Visual C#) o Group Join (Visual Basic) se traduce en una invocación de GroupJoin .In query expression syntax, a join … into (Visual C#) or Group Join (Visual Basic) clause translates to an invocation of GroupJoin.

Consulte también

• Operaciones de combinaciónJoin Operations
• join (Cláusula, Referencia de C#)join clause (C# Reference)
• Group Join (Cláusula, Visual Basic)Group Join Clause (Visual Basic)