Queryable.Any(Of TSource) Method (IQueryable(Of TSource))

 
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Determines whether a sequence contains any elements.

Namespace:   System.Linq
Assembly:  System.Core (in System.Core.dll)

<ExtensionAttribute>
Public Shared Function Any(Of TSource) (
	source As IQueryable(Of TSource)
) As Boolean

Parameters

source
Type: System.Linq.IQueryable(Of TSource)

A sequence to check for being empty.

Return Value

Type: System.Boolean

true if the source sequence contains any elements; otherwise, false.

Type Parameters

TSource

The type of the elements of source.

Exception Condition
ArgumentNullException

source is null.

The Any(Of TSource)(IQueryable(Of TSource)) method generates a MethodCallExpression that represents calling Any(Of TSource)(IQueryable(Of TSource)) itself as a constructed generic method. It then passes the MethodCallExpression to the Execute(Of TResult)(Expression) method of the IQueryProvider represented by the Provider property of the source parameter.

The query behavior that occurs as a result of executing an expression tree that represents calling Any(Of TSource)(IQueryable(Of TSource)) depends on the implementation of the type of the source parameter. The expected behavior is that it determines if source contains any elements.

The following code example demonstrates how to use Any(Of TSource)(IQueryable(Of TSource)) to determine whether a sequence contains any elements.

Dim numbers As New List(Of Integer)(New Integer() {1, 2})

' Determine if the list contains any elements.
Dim hasElements As Boolean = numbers.AsQueryable().Any()

MsgBox(String.Format("The list {0} empty.", _
    IIf(hasElements, "is not", "is")))

' This code produces the following output:
'
' The list is not empty. 

The Boolean value that the Any(Of TSource)(IQueryable(Of TSource)) method returns is typically used in the predicate of a where clause (Where clause in Visual Basic) or a direct call to the Where(Of TSource)(IQueryable(Of TSource), Expression(Of Func(Of TSource, Boolean))) method. The following example demonstrates this use of the Any method.

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

Structure Person
    Public LastName As String
    Public Pets() As Pet
End Structure

Sub AnyEx2()
    Dim people As New List(Of Person)(New Person() _
        {New Person With {.LastName = "Haas", _
                          .Pets = New Pet() {New Pet With {.Name = "Barley", .Age = 10}, _
                                             New Pet With {.Name = "Boots", .Age = 14}, _
                                             New Pet With {.Name = "Whiskers", .Age = 6}}}, _
          New Person With {.LastName = "Fakhouri", _
                           .Pets = New Pet() {New Pet With {.Name = "Snowball", .Age = 1}}}, _
          New Person With {.LastName = "Antebi", _
                           .Pets = New Pet() {}}, _
          New Person With {.LastName = "Philips", _
                           .Pets = New Pet() {New Pet With {.Name = "Sweetie", .Age = 2}, _
                                              New Pet With {.Name = "Rover", .Age = 13}}}})

    ' Determine which people have a non-empty Pet array.
    Dim names = From person In people _
                Where person.Pets.AsQueryable().Any() _
                Select person.LastName

    For Each name As String In names
        Console.WriteLine(name)
    Next

    ' This code produces the following output:
    '
    ' Haas
    ' Fakhouri
    ' Philips

End Sub

Universal Windows Platform
Available since 8
.NET Framework
Available since 3.5
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.1
Windows Phone
Available since 8.1
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