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。Correlates the elements of two sequences based on key equality and groups the results.

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。Correlates the elements of two sequences based on key equality and groups the results. 預設的相等比較子是用於比較索引鍵。The default equality comparer is used to compare keys.

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。Correlates the elements of two sequences based on key equality and groups the results. 指定的 IEqualityComparer<T> 是用於比較索引鍵。A specified IEqualityComparer<T> is used to compare keys.

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。Correlates the elements of two sequences based on key equality and groups the results. 預設的相等比較子是用於比較索引鍵。The default equality comparer is used to compare keys.

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。The type of the elements of the first sequence.

TInner

第二個序列之項目的類型。The type of the elements of the second sequence.

TKey

索引鍵選取器函式所傳回之索引鍵的類型。The type of the keys returned by the key selector functions.

TResult

結果項目的類型。The type of the result elements.

參數

outer
IQueryable<TOuter>

要聯結的第一個序列。The first sequence to join.

inner
IEnumerable<TInner>

要加入第一個序列的序列。The sequence to join to the first sequence.

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。A function to extract the join key from each element of the first sequence.

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。A function to extract the join key from each element of the second sequence.

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。A function to create a result element from an element from the first sequence and a collection of matching elements from the second sequence.

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。An IQueryable<T> that contains elements of type TResult obtained by performing a grouped join on two sequences.

例外狀況

outerinnerouterKeySelectorinnerKeySelectorresultSelectornullouter or inner or outerKeySelector or innerKeySelector or resultSelector is null.

範例

下列程式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>>) 來執行兩個序列的群組聯結。The following code example demonstrates how to use GroupJoin<TOuter,TInner,TKey,TResult>(IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter,TKey>>, Expression<Func<TInner,TKey>>, Expression<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 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 Expression<TDelegate> ,其型別引數是其中一種 Func<T,TResult> 類型。This method has at least one parameter of type Expression<TDelegate> whose type argument is one of the Func<T,TResult> types. 針對這些參數,您可以傳入 lambda 運算式,並將其編譯為 Expression<TDelegate>For these parameters, you can pass in a lambda expression and it will be compiled to an Expression<TDelegate>.

GroupJoin<TOuter,TInner,TKey,TResult>(IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter,TKey>>, Expression<Func<TInner,TKey>>, Expression<Func<TOuter,IEnumerable<TInner>,TResult>>)方法 MethodCallExpression 會產生,代表呼叫 GroupJoin<TOuter,TInner,TKey,TResult>(IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter,TKey>>, Expression<Func<TInner,TKey>>, Expression<Func<TOuter,IEnumerable<TInner>,TResult>>) 本身做為已建立的泛型方法。The GroupJoin<TOuter,TInner,TKey,TResult>(IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter,TKey>>, Expression<Func<TInner,TKey>>, Expression<Func<TOuter,IEnumerable<TInner>,TResult>>) method generates a MethodCallExpression that represents calling GroupJoin<TOuter,TInner,TKey,TResult>(IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter,TKey>>, Expression<Func<TInner,TKey>>, Expression<Func<TOuter,IEnumerable<TInner>,TResult>>) itself as a constructed generic method. 然後,它會將傳遞 MethodCallExpression 給以 CreateQuery<TElement>(Expression) 參數的屬性所表示的方法 IQueryProvider Provider outerIt then passes the MethodCallExpression to the CreateQuery<TElement>(Expression) method of the IQueryProvider represented by the Provider property of the outer parameter.

執行表示呼叫的運算式樹狀架構所產生的查詢行為, GroupJoin<TOuter,TInner,TKey,TResult>(IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter,TKey>>, Expression<Func<TInner,TKey>>, Expression<Func<TOuter,IEnumerable<TInner>,TResult>>) 取決於參數類型的實作為 outerThe query behavior that occurs as a result of executing an expression tree that represents calling GroupJoin<TOuter,TInner,TKey,TResult>(IQueryable<TOuter>, IEnumerable<TInner>, Expression<Func<TOuter,TKey>>, Expression<Func<TInner,TKey>>, Expression<Func<TOuter,IEnumerable<TInner>,TResult>>) depends on the implementation of the type of the outer parameter. 預期的行為是 outerKeySelector 使用和函式 innerKeySelector 來分別從和解壓縮索引 outerinnerThe expected behavior is that the outerKeySelector and innerKeySelector functions are used to extract keys from outer and inner, respectively. 這些索引鍵會針對相等進行比較,以比對中的每個元素 outer 與零或多個元素 innerThese keys are compared for equality to match each element in outer with zero or more elements from inner. 然後叫 resultSelector 用函式,從每個相互關聯的元素群組投影結果物件。Then the resultSelector function is invoked to project a result object from each group of correlated elements.

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>)

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。Correlates the elements of two sequences based on key equality and groups the results. 指定的 IEqualityComparer<T> 是用於比較索引鍵。A specified IEqualityComparer<T> is used to compare keys.

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。The type of the elements of the first sequence.

TInner

第二個序列之項目的類型。The type of the elements of the second sequence.

TKey

索引鍵選取器函式所傳回之索引鍵的類型。The type of the keys returned by the key selector functions.

TResult

結果項目的類型。The type of the result elements.

參數

outer
IQueryable<TOuter>

要聯結的第一個序列。The first sequence to join.

inner
IEnumerable<TInner>

要加入第一個序列的序列。The sequence to join to the first sequence.

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。A function to extract the join key from each element of the first sequence.

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。A function to extract the join key from each element of the second sequence.

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。A function to create a result element from an element from the first sequence and a collection of matching elements from the second sequence.

comparer
IEqualityComparer<TKey>

用來雜湊及比較索引鍵的比較子。A comparer to hash and compare keys.

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。An IQueryable<T> that contains elements of type TResult obtained by performing a grouped join on two sequences.

例外狀況

outerinnerouterKeySelectorinnerKeySelectorresultSelectornullouter or inner or outerKeySelector or innerKeySelector or resultSelector is null.

備註

這個方法至少有一個類型的參數 Expression<TDelegate> ,其型別引數是其中一種 Func<T,TResult> 類型。This method has at least one parameter of type Expression<TDelegate> whose type argument is one of the Func<T,TResult> types. 針對這些參數,您可以傳入 lambda 運算式,並將其編譯為 Expression<TDelegate>For these parameters, you can pass in a lambda expression and it will be compiled to an Expression<TDelegate>.

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>)方法 MethodCallExpression 會產生,代表呼叫 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>) 本身做為已建立的泛型方法。The 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>) method generates a MethodCallExpression that represents calling 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>) itself as a constructed generic method. 然後,它會將傳遞 MethodCallExpression 給以 CreateQuery<TElement>(Expression) 參數的屬性所表示的方法 IQueryProvider Provider outerIt then passes the MethodCallExpression to the CreateQuery<TElement>(Expression) method of the IQueryProvider represented by the Provider property of the outer parameter.

執行表示呼叫的運算式樹狀架構所產生的查詢行為, 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>) 取決於參數類型的實作為 outerThe query behavior that occurs as a result of executing an expression tree that represents calling 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>) depends on the implementation of the type of the outer parameter. 預期的行為是 outerKeySelector 使用和函式 innerKeySelector 來分別從和解壓縮索引 outerinnerThe expected behavior is that the outerKeySelector and innerKeySelector functions are used to extract keys from outer and inner, respectively. 這些索引鍵會使用來比較是否相等 comparerThese keys are compared for equality by using comparer. 比較的結果會用來比對中的每個專案 outer 與零個或多個元素 innerThe outcome of the comparisons is used to match each element in outer with zero or more elements from inner. 然後叫 resultSelector 用函式,從每個相互關聯的元素群組投影結果物件。Then the resultSelector function is invoked to project a result object from each group of correlated elements.

適用於