Queryable.Any(Of TSource) Method (IQueryable(Of TSource))
[ This article is for Windows Phone 8 developers. If you’re developing for Windows 10, see the latest documentation. ]
Determines whether a sequence contains any elements.
Assembly: System.Core (in System.Core.dll)
'Declaration <ExtensionAttribute> _ Public Shared Function Any(Of TSource) ( _ source As IQueryable(Of TSource) _ ) As Boolean
Type Parameters
- TSource
The type of the elements of source.
Parameters
- source
- Type: System.Linq.IQueryable(Of TSource)
A sequence to check for being empty.
Return Value
Type: System.Booleantrue if the source sequence contains any elements; otherwise, false.
Usage Note
In Visual Basic and C#, you can call this method as an instance method on any object of type IQueryable(Of TSource). When you use instance method syntax to call this method, omit the first parameter.| Exception | Condition |
|---|---|
| ArgumentNullException | source is Nothing. |
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()
outputBlock.Text &= String.Format("The list {0} empty.", _
IIf(hasElements, "is not", "is")) & vbCrLf
' 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 outputBlock.Text &= name & vbCrLf Next ' This code produces the following output: ' ' Haas ' Fakhouri ' Philips End Sub