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Queryable.Contains(Of TSource) Method (IQueryable(Of TSource), TSource)

Determines whether a sequence contains a specified element by using the default equality comparer.

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

'Declaration
<ExtensionAttribute> _
Public Shared Function Contains(Of TSource) ( _
	source As IQueryable(Of TSource), _
	item As TSource _
) As Boolean

Type Parameters

TSource

The type of the elements of source.

Parameters

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

An IQueryable(Of T) in which to locate item.

item
Type: TSource

The object to locate in the sequence.

Return Value

Type: System.Boolean
true if the input sequence contains an element that has the specified value; 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. For more information, see Extension Methods (Visual Basic) or Extension Methods (C# Programming Guide).

ExceptionCondition
ArgumentNullException

source is Nothing.

The Contains(Of TSource)(IQueryable(Of TSource), TSource) method generates a MethodCallExpression that represents calling Contains(Of TSource)(IQueryable(Of TSource), 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 Contains(Of TSource)(IQueryable(Of TSource), TSource) depends on the implementation of the type of the source parameter. The expected behavior is that it determines if source contains item.

The following code example demonstrates how to use Contains(Of TSource)(IQueryable(Of TSource), TSource) to determine whether a sequence contains a specific element.

        Dim fruits() As String = {"apple", "banana", "mango", _
                                "orange", "passionfruit", "grape"}

        ' The string to search for in the array. 
        Dim mango As String = "mango" 

        Dim hasMango As Boolean = fruits.AsQueryable().Contains(mango)

        MsgBox(String.Format("The array {0} contain '{1}'.", _
                IIf(hasMango, "does", "does not"), mango))

        ' This code produces the following output: 
        
        ' The array does contain 'mango'. 

.NET Framework

Supported in: 4.5, 4, 3.5

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Store apps

Supported in: Windows 8

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone Silverlight 8.1, Windows Phone Silverlight 8

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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