Queryable.Concat<TSource>(IQueryable<TSource>, IEnumerable<TSource>) Metoda

Definice

Zřetězí dvě sekvence.Concatenates two sequences.

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)

Parametry typu

TSource

Typ prvků vstupních sekvencí.The type of the elements of the input sequences.

Parametry

source1
IQueryable<TSource>

První sekvence, která se má zřetězitThe first sequence to concatenate.

source2
IEnumerable<TSource>

Sekvence, která se má zřetězit k první sekvenci.The sequence to concatenate to the first sequence.

Návraty

IQueryable<TSource>

Obsahující IQueryable<T> zřetězené prvky dvou vstupních sekvencí.An IQueryable<T> that contains the concatenated elements of the two input sequences.

Výjimky

source1 nebo source2 je null .source1 or source2 is null.

Příklady

Následující příklad kódu ukazuje, jak použít Concat<TSource>(IQueryable<TSource>, IEnumerable<TSource>) ke zřetězení dvou sekvencí.The following code example demonstrates how to use Concat<TSource>(IQueryable<TSource>, IEnumerable<TSource>) to concatenate two sequences.

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

Poznámky

Concat<TSource>(IQueryable<TSource>, IEnumerable<TSource>)Metoda generuje MethodCallExpression , který reprezentuje volání Concat<TSource>(IQueryable<TSource>, IEnumerable<TSource>) sebe sama jako vytvořenou obecnou metodu.The Concat<TSource>(IQueryable<TSource>, IEnumerable<TSource>) method generates a MethodCallExpression that represents calling Concat<TSource>(IQueryable<TSource>, IEnumerable<TSource>) itself as a constructed generic method. Poté předá MethodCallExpression CreateQuery<TElement>(Expression) metodě IQueryProvider reprezentované Provider vlastností source1 parametru.It then passes the MethodCallExpression to the CreateQuery<TElement>(Expression) method of the IQueryProvider represented by the Provider property of the source1 parameter.

Chování dotazu, k němuž dojde v důsledku provádění stromu výrazu, který představuje volání, Concat<TSource>(IQueryable<TSource>, IEnumerable<TSource>) závisí na implementaci typu source1 parametru.The query behavior that occurs as a result of executing an expression tree that represents calling Concat<TSource>(IQueryable<TSource>, IEnumerable<TSource>) depends on the implementation of the type of the source1 parameter. Očekávané chování je, že prvky v source2 jsou zřetězeny k source1 objektům, aby bylo možné vytvořit novou sekvenci.The expected behavior is that the elements in source2 are concatenated to those of source1 to create a new sequence.

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