Статья
11/18/2011

Queryable.Any<TSource> Method (IQueryable<TSource>, Expression<Func<TSource, Boolean>>)

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Determines whether any element of a sequence satisfies a condition.

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

Syntax

'Declaration
<ExtensionAttribute> _
Public Shared Function Any(Of TSource) ( _
    source As IQueryable(Of TSource), _
    predicate As Expression(Of Func(Of TSource, Boolean)) _
) As Boolean

public static bool Any<TSource>(
    this IQueryable<TSource> source,
    Expression<Func<TSource, bool>> predicate
)

Type Parameters

TSource
The type of the elements of source.

Parameters

source
Type: System.Linq.IQueryable<TSource>
A sequence whose elements to test for a condition.

predicate
Type: System.Linq.Expressions.Expression<Func<TSource, Boolean>>
A function to test each element for a condition.

Return Value

Type: System.Boolean
true if any elements in the source sequence pass the test in the specified predicate; 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.

Exceptions

Exception	Condition
ArgumentNullException	source or predicate is nulla null reference (Nothing in Visual Basic).

Remarks

This method has at least one parameter of type Expression<TDelegate> whose type argument is one of the Func<T, TResult> types. For these parameters, you can pass in a lambda expression and it will be compiled to an Expression<TDelegate>.

The Any<TSource>(IQueryable<TSource>, Expression<Func<TSource, Boolean>>) method generates a MethodCallExpression that represents calling Any<TSource>(IQueryable<TSource>, Expression<Func<TSource, Boolean>>) 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 Any<TSource>(IQueryable<TSource>, Expression<Func<TSource, Boolean>>) depends on the implementation of the type of the source parameter. The expected behavior is that it determines if any of the elements of source satisfy the condition specified by predicate.

Examples

The following code example demonstrates how to use Any<TSource>(IQueryable<TSource>, Expression<Func<TSource, Boolean>>) to determine whether any element in a sequence satisfies a condition.

   Structure Pet
      Dim Name As String
      Dim Age As Integer
      Dim Vaccinated As Boolean
   End Structure

   Shared Sub AnyEx3()
      ' Create an array of Pet objects.
      Dim pets() As Pet = _
          {New Pet With {.Name = "Barley", .Age = 8, .Vaccinated = True}, _
           New Pet With {.Name = "Boots", .Age = 4, .Vaccinated = False}, _
           New Pet With {.Name = "Whiskers", .Age = 1, .Vaccinated = False}}

      ' Determine whether any pets over age 1 are also unvaccinated.
      Dim unvaccinated As Boolean = _
      pets.AsQueryable().Any(Function(p) p.Age > 1 And p.Vaccinated = False)

      outputBlock.Text &= String.Format( _
          "There {0} unvaccinated animals over age one.", _
          IIf(unvaccinated, "are", "are not any")) & vbCrLf
   End Sub

   ' This code produces the following output:
   '
   '  There are unvaccinated animals over age one.

         class Pet
         {
            public string Name { get; set; }
            public int Age { get; set; }
            public bool Vaccinated { get; set; }
         }

         public static void AnyEx3()
         {
            // Create an array of Pet objects.
            Pet[] pets =
                    { new Pet { Name="Barley", Age=8, Vaccinated=true },
                      new Pet { Name="Boots", Age=4, Vaccinated=false },
                      new Pet { Name="Whiskers", Age=1, Vaccinated=false } };

            // Determine whether any pets over age 1 are also unvaccinated.
            bool unvaccinated =
                pets.AsQueryable().Any(p => p.Age > 1 && p.Vaccinated == false);

            outputBlock.Text += String.Format(
                "There {0} unvaccinated animals over age one.",
                unvaccinated ? "are" : "are not any") + "\n";
         }

         // This code produces the following output:
         //
         //  There are unvaccinated animals over age one.

Version Information

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

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