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)

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

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.

Type Parameters

TSource

The type of the elements of source.

Exception Condition
ArgumentNullException

source is null.

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'. 

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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