Queryable.Concat<TSource> 方法

定義

命名空間:

System.Linq

組件:

System.Linq.Queryable.dll

來源:

Queryable.cs

串連兩個序列。

public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
 static System::Linq::IQueryable<TSource> ^ Concat(System::Linq::IQueryable<TSource> ^ source1, System::Collections::Generic::IEnumerable<TSource> ^ source2);

public static System.Linq.IQueryable<TSource> Concat<TSource> (this System.Linq.IQueryable<TSource> source1, System.Collections.Generic.IEnumerable<TSource> source2);

static member Concat : System.Linq.IQueryable<'Source> * seq<'Source> -> System.Linq.IQueryable<'Source>

<Extension()>
Public Function Concat(Of TSource) (source1 As IQueryable(Of TSource), source2 As IEnumerable(Of TSource)) As IQueryable(Of TSource)

類型參數

TSource

輸入序列之項目的類型。

參數

source1

IQueryable<TSource>

要串連的第一個序列。

source2

IEnumerable<TSource>

要串連到第一個序列的序列。

傳回

IQueryable<TSource>

IQueryable<T>，其中包含兩個輸入序列的串連項目。

例外狀況

ArgumentNullException

source1 或 source2 為 null。

範例

下列程式代碼範例示範如何使用 Concat<TSource>(IQueryable<TSource>, IEnumerable<TSource>) 來串連兩個序列。

class Pet
{
    public string Name { get; set; }
    public int Age { get; set; }
}

// This method creates and returns an array of Pet objects.
static Pet[] GetCats()
{
    Pet[] cats = { new Pet { Name="Barley", Age=8 },
                   new Pet { Name="Boots", Age=4 },
                   new Pet { Name="Whiskers", Age=1 } };
    return cats;
}

// This method creates and returns an array of Pet objects.
static Pet[] GetDogs()
{
    Pet[] dogs = { new Pet { Name="Bounder", Age=3 },
                   new Pet { Name="Snoopy", Age=14 },
                   new Pet { Name="Fido", Age=9 } };
    return dogs;
}

public static void ConcatEx1()
{
    Pet[] cats = GetCats();
    Pet[] dogs = GetDogs();

    // Concatenate a collection of cat names to a
    // collection of dog names by using Concat().
    IEnumerable<string> query =
        cats.AsQueryable()
        .Select(cat => cat.Name)
        .Concat(dogs.Select(dog => dog.Name));

    foreach (string name in query)
        Console.WriteLine(name);
}

// This code produces the following output:
//
// Barley
// Boots
// Whiskers
// Bounder
// Snoopy
// Fido

' This method creates and returns an array of Pet objects.
Shared Function GetCats() As Pet()
    Dim cats() As Pet = _
        {New Pet With {.Name = "Barley", .Age = 8}, _
         New Pet With {.Name = "Boots", .Age = 4}, _
         New Pet With {.Name = "Whiskers", .Age = 1}}

    Return cats
End Function

' This method creates and returns an array of Pet objects.
Shared Function GetDogs() As Pet()
    Dim dogs() As Pet = _
        {New Pet With {.Name = "Bounder", .Age = 3}, _
         New Pet With {.Name = "Snoopy", .Age = 14}, _
         New Pet With {.Name = "Fido", .Age = 9}}

    Return dogs
End Function

Shared Sub ConcatEx1()
    Dim cats() As Pet = GetCats()
    Dim dogs() As Pet = GetDogs()

    ' Concatenate a collection of cat names to a
    ' collection of dog names by using Concat().
    Dim query As IEnumerable(Of String) = _
        cats.AsQueryable() _
        .Select(Function(cat) cat.Name) _
        .Concat(dogs.Select(Function(dog) dog.Name))

    For Each name As String In query
        MsgBox(name)
    Next
End Sub

Structure Pet
    Dim Name As String
    Dim Age As Integer
End Structure

' This code produces the following output:
'
' Barley
' Boots
' Whiskers
' Bounder
' Snoopy
' Fido

備註

方法 Concat<TSource>(IQueryable<TSource>, IEnumerable<TSource>) 會產生 ， MethodCallExpression 表示呼叫 Concat<TSource>(IQueryable<TSource>, IEnumerable<TSource>) 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IQueryProvidersource1。

執行表示呼叫 Concat<TSource>(IQueryable<TSource>, IEnumerable<TSource>) 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 source1 。 預期的行為是 中的 source2 專案會串連至 的 source1 元素，以建立新的序列。