Queryable.Contains<TSource> Method (IQueryable<TSource>, TSource, IEqualityComparer<TSource>)

Determines whether a sequence contains a specified element by using a specified IEqualityComparer<T>.

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

public static bool Contains<TSource>(
	this IQueryable<TSource> source,
	TSource item,
	IEqualityComparer<TSource> comparer

Type Parameters


The type of the elements of source.


Type: System.Linq.IQueryable<TSource>

An IQueryable<T> in which to locate item.

Type: TSource

The object to locate in the sequence.

Type: System.Collections.Generic.IEqualityComparer<TSource>

An IEqualityComparer<T> to compare values.

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<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).


source is null.

The Contains<TSource>(IQueryable<TSource>, TSource, IEqualityComparer<TSource>) method generates a MethodCallExpression that represents calling Contains<TSource>(IQueryable<TSource>, TSource, IEqualityComparer<TSource>) itself as a constructed generic method. It then passes the MethodCallExpression to the Execute<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<TSource>(IQueryable<TSource>, TSource, IEqualityComparer<TSource>) depends on the implementation of the type of the source parameter. The expected behavior is that it determines if source contains item by using comparer to compare values.

Windows 7, Windows Vista, Windows XP SP2, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003

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

.NET Framework

Supported in: 3.5
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