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Queryable.GroupJoin 方法

定義

根據索引鍵相等與否,將兩個序列的項目相互關聯,並群組產生的結果。

多載

GroupJoin<TOuter,TInner,TKey,TResult>(IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter,TKey>>, Expression<Func<TInner,TKey>>, Expression<Func<TOuter,IEnumerable<TInner>,TResult>>)

根據索引鍵相等與否,將兩個序列的項目相互關聯,並群組產生的結果。 預設的相等比較子是用於比較索引鍵。

GroupJoin<TOuter,TInner,TKey,TResult>(IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter,TKey>>, Expression<Func<TInner,TKey>>, Expression<Func<TOuter,IEnumerable<TInner>,TResult>>, IEqualityComparer<TKey>)

根據索引鍵相等與否,將兩個序列的項目相互關聯,並群組產生的結果。 指定的 IEqualityComparer<T> 是用於比較索引鍵。

GroupJoin<TOuter,TInner,TKey,TResult>(IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter,TKey>>, Expression<Func<TInner,TKey>>, Expression<Func<TOuter,IEnumerable<TInner>,TResult>>)

來源:
Queryable.cs
來源:
Queryable.cs
來源:
Queryable.cs

根據索引鍵相等與否,將兩個序列的項目相互關聯,並群組產生的結果。 預設的相等比較子是用於比較索引鍵。

public:
generic <typename TOuter, typename TInner, typename TKey, typename TResult>
[System::Runtime::CompilerServices::Extension]
 static System::Linq::IQueryable<TResult> ^ GroupJoin(System::Linq::IQueryable<TOuter> ^ outer, System::Collections::Generic::IEnumerable<TInner> ^ inner, System::Linq::Expressions::Expression<Func<TOuter, TKey> ^> ^ outerKeySelector, System::Linq::Expressions::Expression<Func<TInner, TKey> ^> ^ innerKeySelector, System::Linq::Expressions::Expression<Func<TOuter, System::Collections::Generic::IEnumerable<TInner> ^, TResult> ^> ^ resultSelector);
public static System.Linq.IQueryable<TResult> GroupJoin<TOuter,TInner,TKey,TResult> (this System.Linq.IQueryable<TOuter> outer, System.Collections.Generic.IEnumerable<TInner> inner, System.Linq.Expressions.Expression<Func<TOuter,TKey>> outerKeySelector, System.Linq.Expressions.Expression<Func<TInner,TKey>> innerKeySelector, System.Linq.Expressions.Expression<Func<TOuter,System.Collections.Generic.IEnumerable<TInner>,TResult>> resultSelector);
static member GroupJoin : System.Linq.IQueryable<'Outer> * seq<'Inner> * System.Linq.Expressions.Expression<Func<'Outer, 'Key>> * System.Linq.Expressions.Expression<Func<'Inner, 'Key>> * System.Linq.Expressions.Expression<Func<'Outer, seq<'Inner>, 'Result>> -> System.Linq.IQueryable<'Result>
<Extension()>
Public Function GroupJoin(Of TOuter, TInner, TKey, TResult) (outer As IQueryable(Of TOuter), inner As IEnumerable(Of TInner), outerKeySelector As Expression(Of Func(Of TOuter, TKey)), innerKeySelector As Expression(Of Func(Of TInner, TKey)), resultSelector As Expression(Of Func(Of TOuter, IEnumerable(Of TInner), TResult))) As IQueryable(Of TResult)

類型參數

TOuter

第一個序列之項目的類型。

TInner

第二個序列之項目的類型。

TKey

索引鍵選取器函式所傳回之索引鍵的類型。

TResult

結果項目的類型。

參數

outer
IQueryable<TOuter>

要聯結的第一個序列。

inner
IEnumerable<TInner>

要加入第一個序列的序列。

outerKeySelector
Expression<Func<TOuter,TKey>>

用來從第一個序列各個項目擷取聯結索引鍵的函式。

innerKeySelector
Expression<Func<TInner,TKey>>

用來從第二個序列各個項目擷取聯結索引鍵的函式。

resultSelector
Expression<Func<TOuter,IEnumerable<TInner>,TResult>>

函式,用來從第一個序列的項目以及第二個序列的相符項目集合建立結果項目。

傳回

IQueryable<TResult>

IQueryable<T>,其中包含透過對兩個序列執行群組聯結所取得之型別 TResult 的項目。

例外狀況

outerinnerouterKeySelectorinnerKeySelectorresultSelectornull

範例

下列程式代碼範例示範如何使用 GroupJoin<TOuter,TInner,TKey,TResult>(IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter,TKey>>, Expression<Func<TInner,TKey>>, Expression<Func<TOuter,IEnumerable<TInner>,TResult>>) 在兩個序列上執行群組聯結。

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 that are owned by them.
    var query =
        people.AsQueryable().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

Shared 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 list where each element is an anonymous 
    ' type that contains a person's name and a collection
    ' of the names of the pets that are owned by them.
    Dim query = _
        people.AsQueryable().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(String.Format("{0}:", obj.OwnerName))
        ' Output each of the owner's pet's names.
        For Each pet As String In obj.Pets
            output.AppendLine(String.Format("  {0}", pet))
        Next
    Next

    ' Display the output.
    MsgBox(output.ToString())
End Sub

' This code produces the following output:

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

備註

這個方法至少有一個類型的參數,其類型 Expression<TDelegate> 自變數為其中一個型別 Func<T,TResult> 。 針對這些參數,您可以傳入 Lambda 運算式,並將它編譯為 Expression<TDelegate>

方法 GroupJoin<TOuter,TInner,TKey,TResult>(IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter,TKey>>, Expression<Func<TInner,TKey>>, Expression<Func<TOuter,IEnumerable<TInner>,TResult>>) 會產生 , MethodCallExpression 表示呼叫 GroupJoin<TOuter,TInner,TKey,TResult>(IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter,TKey>>, Expression<Func<TInner,TKey>>, Expression<Func<TOuter,IEnumerable<TInner>,TResult>>) 本身為建構的泛型方法。 然後,它會將 傳遞給 MethodCallExpressionCreateQuery<TElement>(Expression) 參數之 屬性所Provider表示的方法IQueryProviderouter

執行表示呼叫 GroupJoin<TOuter,TInner,TKey,TResult>(IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter,TKey>>, Expression<Func<TInner,TKey>>, Expression<Func<TOuter,IEnumerable<TInner>,TResult>>) 的表達式樹狀結構所產生的查詢行為,取決於參數類型的實作 outer 。 預期的行為是 outerKeySelectorinnerKeySelector 函式分別用來擷 outer 取 和 inner的索引鍵。 系統會比較這些索引鍵是否相等,以比對 中的 outer 每個元素與 中零個或多個元素 inner。 然後,會叫用函 resultSelector 式,從每個相互關聯的專案群組投影結果物件。

適用於

GroupJoin<TOuter,TInner,TKey,TResult>(IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter,TKey>>, Expression<Func<TInner,TKey>>, Expression<Func<TOuter,IEnumerable<TInner>,TResult>>, IEqualityComparer<TKey>)

來源:
Queryable.cs
來源:
Queryable.cs
來源:
Queryable.cs

根據索引鍵相等與否,將兩個序列的項目相互關聯,並群組產生的結果。 指定的 IEqualityComparer<T> 是用於比較索引鍵。

public:
generic <typename TOuter, typename TInner, typename TKey, typename TResult>
[System::Runtime::CompilerServices::Extension]
 static System::Linq::IQueryable<TResult> ^ GroupJoin(System::Linq::IQueryable<TOuter> ^ outer, System::Collections::Generic::IEnumerable<TInner> ^ inner, System::Linq::Expressions::Expression<Func<TOuter, TKey> ^> ^ outerKeySelector, System::Linq::Expressions::Expression<Func<TInner, TKey> ^> ^ innerKeySelector, System::Linq::Expressions::Expression<Func<TOuter, System::Collections::Generic::IEnumerable<TInner> ^, TResult> ^> ^ resultSelector, System::Collections::Generic::IEqualityComparer<TKey> ^ comparer);
public static System.Linq.IQueryable<TResult> GroupJoin<TOuter,TInner,TKey,TResult> (this System.Linq.IQueryable<TOuter> outer, System.Collections.Generic.IEnumerable<TInner> inner, System.Linq.Expressions.Expression<Func<TOuter,TKey>> outerKeySelector, System.Linq.Expressions.Expression<Func<TInner,TKey>> innerKeySelector, System.Linq.Expressions.Expression<Func<TOuter,System.Collections.Generic.IEnumerable<TInner>,TResult>> resultSelector, System.Collections.Generic.IEqualityComparer<TKey> comparer);
public static System.Linq.IQueryable<TResult> GroupJoin<TOuter,TInner,TKey,TResult> (this System.Linq.IQueryable<TOuter> outer, System.Collections.Generic.IEnumerable<TInner> inner, System.Linq.Expressions.Expression<Func<TOuter,TKey>> outerKeySelector, System.Linq.Expressions.Expression<Func<TInner,TKey>> innerKeySelector, System.Linq.Expressions.Expression<Func<TOuter,System.Collections.Generic.IEnumerable<TInner>,TResult>> resultSelector, System.Collections.Generic.IEqualityComparer<TKey>? comparer);
static member GroupJoin : System.Linq.IQueryable<'Outer> * seq<'Inner> * System.Linq.Expressions.Expression<Func<'Outer, 'Key>> * System.Linq.Expressions.Expression<Func<'Inner, 'Key>> * System.Linq.Expressions.Expression<Func<'Outer, seq<'Inner>, 'Result>> * System.Collections.Generic.IEqualityComparer<'Key> -> System.Linq.IQueryable<'Result>
<Extension()>
Public Function GroupJoin(Of TOuter, TInner, TKey, TResult) (outer As IQueryable(Of TOuter), inner As IEnumerable(Of TInner), outerKeySelector As Expression(Of Func(Of TOuter, TKey)), innerKeySelector As Expression(Of Func(Of TInner, TKey)), resultSelector As Expression(Of Func(Of TOuter, IEnumerable(Of TInner), TResult)), comparer As IEqualityComparer(Of TKey)) As IQueryable(Of TResult)

類型參數

TOuter

第一個序列之項目的類型。

TInner

第二個序列之項目的類型。

TKey

索引鍵選取器函式所傳回之索引鍵的類型。

TResult

結果項目的類型。

參數

outer
IQueryable<TOuter>

要聯結的第一個序列。

inner
IEnumerable<TInner>

要加入第一個序列的序列。

outerKeySelector
Expression<Func<TOuter,TKey>>

用來從第一個序列各個項目擷取聯結索引鍵的函式。

innerKeySelector
Expression<Func<TInner,TKey>>

用來從第二個序列各個項目擷取聯結索引鍵的函式。

resultSelector
Expression<Func<TOuter,IEnumerable<TInner>,TResult>>

函式,用來從第一個序列的項目以及第二個序列的相符項目集合建立結果項目。

comparer
IEqualityComparer<TKey>

用來雜湊及比較索引鍵的比較子。

傳回

IQueryable<TResult>

IQueryable<T>,其中包含透過對兩個序列執行群組聯結所取得之型別 TResult 的項目。

例外狀況

outerinnerouterKeySelectorinnerKeySelectorresultSelectornull

備註

這個方法至少有一個類型的參數,其類型 Expression<TDelegate> 自變數為其中一個型別 Func<T,TResult> 。 針對這些參數,您可以傳入 Lambda 運算式,並將它編譯為 Expression<TDelegate>

方法 GroupJoin<TOuter,TInner,TKey,TResult>(IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter,TKey>>, Expression<Func<TInner,TKey>>, Expression<Func<TOuter,IEnumerable<TInner>,TResult>>, IEqualityComparer<TKey>) 會產生 , MethodCallExpression 表示呼叫 GroupJoin<TOuter,TInner,TKey,TResult>(IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter,TKey>>, Expression<Func<TInner,TKey>>, Expression<Func<TOuter,IEnumerable<TInner>,TResult>>, IEqualityComparer<TKey>) 本身為建構的泛型方法。 然後,它會將 傳遞給 MethodCallExpressionCreateQuery<TElement>(Expression) 參數之 屬性所Provider表示的方法IQueryProviderouter

執行表示呼叫 GroupJoin<TOuter,TInner,TKey,TResult>(IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter,TKey>>, Expression<Func<TInner,TKey>>, Expression<Func<TOuter,IEnumerable<TInner>,TResult>>, IEqualityComparer<TKey>) 的表達式樹狀結構所產生的查詢行為,取決於參數類型的實作 outer 。 預期的行為是 outerKeySelectorinnerKeySelector 函式分別用來擷 outer 取 和 inner的索引鍵。 使用 來比較這些索引鍵是否相等 comparer。 比較的結果是用來比對 中 outer 每個元素與 中的零個或多個專案 inner。 然後,會叫用函 resultSelector 式,從每個相互關聯的專案群組投影結果物件。

適用於