Contains(TSource) Method (IQueryable(TSource), TSource, IEqualityComparer(TSource))

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: 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.

Type Parameters


The type of the elements of source.

Exception Condition

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.

Universal Windows Platform
Available since 4.5
.NET Framework
Available since 3.5
Portable Class Library
Supported in: portable .NET platforms
Available since 2.0
Windows Phone Silverlight
Available since 7.1
Windows Phone
Available since 8.1
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