Queryable.Contains(Of TSource) Method (IQueryable(Of TSource), TSource, IEqualityComparer(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 a specified element by using a specified IEqualityComparer(Of T).
Assembly: System.Core (in System.Core.dll)
'Declaration <ExtensionAttribute> _ Public Shared Function Contains(Of TSource) ( _ source As IQueryable(Of TSource), _ item As TSource, _ comparer As IEqualityComparer(Of 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.
- comparer
- Type: System.Collections.Generic.IEqualityComparer(Of TSource)
An IEqualityComparer(Of T) to compare values.
Return Value
Type: System.Booleantrue 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.| Exception | Condition |
|---|---|
| ArgumentNullException | source is Nothing. |
The Contains(Of TSource)(IQueryable(Of TSource), TSource, IEqualityComparer(Of TSource)) method generates a MethodCallExpression that represents calling Contains(Of TSource)(IQueryable(Of TSource), TSource, IEqualityComparer(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 Contains(Of TSource)(IQueryable(Of TSource), TSource, IEqualityComparer(Of 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.